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1. Turn the ignition switch to LOCK (0).
2. Reconnect all connectors.
3. Turn the ignition switch to ON (II).
4. Reset the PCM with the HDS See HOW TO TROUBLESHOOT THE A/T SYSTEM or HOW
TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS .
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5. DO THE PCM IDLE LEARN PROCEDURE .
6. Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC Pending DTC Freeze Frame
P0223 TP SENSOR B CIRCUIT HIGH VOLTAGE
Is DTC P0223 indicated?
YES : Check for poor connections or loose terminals at the throttle body and the PCM. If the PCM was
updated, substitute a known-good PCM See PCM UPDATE or PCM REMOVAL AND
INSTALLATION , then recheck. If the PCM was substituted, go to step 1.
NO : Troubleshooting is complete. If the PCM was substituted, replace the original PCM See PCM
REMOVAL AND INSTALLATION or PCM UPDATE . If any other Pending or Confirmed DTCs are
indicated, go to the indicated DTC's troubleshooting.
DTC P0300: RANDOM MISFIRE DETECTED; DTC P0301: NO. 1 CYLINDER
MISFIRE DETECTED; DTC P0302: NO. 2 CYLINDER MISFIRE DETECTED;
DTC P0303: NO. 3 CYLINDER MISFIRE DETECTED; DTC P0304: NO. 4
CYLINDER MISFIRE DETECTED
Fig. 99: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (1 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 100: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (2 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 101: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (3 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 102: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (4 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 103: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (5 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 104: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (6 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 105: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (7 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 106: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (8 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 107: DTC Troubleshooting Flow Chart - P0300, P0301, P0302, P0303, P0304 (9 Of 9)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
NOTE:
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Before you troubleshoot, record all freeze data and any on-board
snapshot, and review the general troubleshooting information See HOW
TO TROUBLESHOOT THE A/T SYSTEM or HOW TO TROUBLESHOOT THE
FUEL AND EMISSIONS SYSTEMS .
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Do not clear the DTC until the cause of the misfire is fixed. Valuable data
required for troubleshooting will be lost if the DTC is cleared. The data will
also be lost even if freeze data and the on-board snapshot is saved.
If the misfire is frequent enough to trigger detection of increased
emissions during two consecutive driving cycles, the MIL will come on,
and DTC P0300 (and some combination of P0301 through P0304) will be
stored.
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If the misfire is frequent enough to damage the catalyst, the MIL will flash
whenever the misfire occurs, and DTC P0300 (and some combination of
P0301 through P0304) will be stored. When the misfire stops, the MIL will
remain on.
Troubleshoot the following DTCs first, if any of them were stored along
with the random misfire DTC(s) (Because parts can sometimes fail without
setting DTC's you should also do a physical inspection of the systems
listed below):
P0102, P0103: MAF sensor
P0107, P0108: MAP sensor
P0171, P0172: Fuel system
P0201, P0202, P0203, P0204: No. 1-No. 4 cylinder injector
P0335, P0339: CKP sensor
P0365, P0369: CMP sensor B
P0351, P0352, P0353, P0354: No. 1 -No. 4 cylinder ignition coil(s)
P2646, P2647, P2648, P2649: VTEC system
DTC Description
P0300 RANDOM MISFIRE
Confirmed DTC Pending DTC Freeze Frame
P0301 No. 1 CYLINDER MISFIRE DETECTED
P0302 No. 2 CYLINDER MISFIRE DETECTED
P0303 No. 3 CYLINDER MISFIRE DETECTED
P0304 No. 4 CYLINDER MISFIRE DETECTED
1. Problem verification-Idle
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1. Record the FREEZE DATA and the ONBOARD SNAPSHOT with the HDS.
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2. Start the engine, and let it idle.
3. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Are the misfire counts increasing on any cylinder at idle?
YES : The engine is misfiring at idle, go to step 2.
NO : The engine does not misfire at idle, go to step 3.
2. Determine Affected Cylinders
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1. Continue to monitor the misfire parameters in the DATA LIST.
Current conditions
Signal
Values
Unit
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Are misfire counts generally isolated to a single cylinder?
YES : The misfire is isolated to a single cylinder.
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If the misfire counts are increasing every engine revolution (completely inactive cylinder), start the
Single Cylinder Continuous Misfire at Idle troubleshooting on step 6.
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If the misfire counts are increasing every few engine revolutions (partially inactive cylinder), start
the Single Cylinder Non-Continuous Misfire at Idle troubleshooting on step 21.
NO : The misfire affects multiple cylinders.
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If the misfire counts are increasing every engine revolution (completely inactive cylinder), start the
Multiple Cylinder Continuous Misfire at Idle troubleshooting on step 30.
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If the misfire counts are increasing every few engine revolutions (partially inactive cylinder), start
the Multiple Cylinder Non-Continuous Misfire at Idle troubleshooting on step 48.
3. Problem verification-Static Load
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1. Increase the engine speed to 3, 500 RPM.
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2. Hold the engine speed steady, and monitor the misfire parameters in the DATA LIST.
Current conditions
Signal
Values
Unit
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Are the misfire counts increasing on any cylinder?
YES : The engine is misfiring under load. Go to step 4.
NO : The engine does not misfire under a static load. Go to step 5.
4. Determine Affected Cylinders
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1. Continue to monitor the misfire parameters in the DATA LIST.
Current conditions
Signal
Values
Unit
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Are misfire counts generally isolated to a single cylinder?
YES : The misfire is isolated to a single cylinder, start the Single Cylinder Misfire. Under Load
troubleshooting on step 58.
NO : The misfire affects multiple cylinders, start the Multiple Cylinder Misfire. Under Load
troubleshooting on step 65.
5. Problem verification -- OBD Snapshot
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1. Open the ONBOARD SNAPSHOT with the HDS.
2. Scroll through the snapshot, and find when the MISFIRE value begins to increase.
3. Record the value of these parameters as the MISFIRE value increases:
Signal
Value Units
ECT SENSOR 1
ENGINE SPEED
VEHICLE SPEED
MAP SENSOR
TP SENSOR
Β°F
RPM
MPH
V
V
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4. Drive the vehicle according to the conditions you identified above while monitoring the misfire
counts.
Current conditions
Signal
Values
Unit
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Are the misfire counts increasing on any cylinder?
YES : The engine is misfiring under the specific operating conditions above.
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If the misfire occurred when the engine was cold, start the Misfire When Cold troubleshooting on
step 72.
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If the misfire occurred when the engine was loaded, go to step 4.
NO : Intermittent failure; the engine is not misfiring at this time.
NOTE: If the misfire can not be reproduced, there is a possibility that the problem
may have been caused by poor quality fuel. The problem may have
disappeared after refueling with fresh fuel. The MIL DIST (MIL Distance)
value in the Data List in combination with the fuel level may help you make
this determination.
6. Check Ignition Coil Spark
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1. Turn the ignition switch to LOCK (0).
2. Remove the ignition coil from the problem cylinder.
3. Connect a commercially available spark tester between the ignition coil and engine ground.
4. Start the engine with the ignition coil connected.
Does the ignition coil produce a spark?
YES : The ignition coil wiring is OK. Go to step 14.
NO : There is a problem with the ignition coil, or the Ignition coil circuit. Go to step 7.
7. Ignition Coil Check
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1. Exchange the ignition coil on the problem cylinder with a normally operating cylinder.
2. Connect a commercially available spark tester between the ignition coil and engine ground.
3. Start the engine with the ignition coil connected.
Does the ignition coil produce a spark?
YES : The ignition coil has a failure. REPLACE THE IGNITION COIL , and then do the repair
verification .
NO : There is a problem with the ignition coil circuit. Go to step 8.
8. Check Ignition Coil Power and Ground
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1. Disconnect the ignition coil 3P connector from the problem cylinder.
2. Turn the ignition switch to ON (II).
3. Measure the voltage between ignition coil 3P connector terminals No. 1 (power) and No. 2
(ground).
NOTE:
After the ignition switch is turned to LOCK (0), this circuit may still
show battery voltage for a period of time. This is normal.
Fig. 108: Measuring Voltage Between Ignition Coil 3P Connector Terminals No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES : The ignition coil power and ground circuits are OK. Go to step 9.
NO : There is a problem with the ignition coil power or ground circuit. Go to step 13.
9. Check Ignition Coil Control Short to Power
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1. Turn the ignition switch to ON (II).
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2. Measure the voltage between ignition coil 3P connector terminals No. 3 (Ignition Control) and
body ground.
Fig. 109: Measuring Voltage Between Ignition Coil 3P Connector Terminals No. 3 (Ignition
Control) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 4 V or more?
YES : The ignition coil control circuit is shorted to power. Go to step 10.
NO : The ignition coil control circuit is not shorted to power. Go to step 11.
10. Isolate Ignition Coil Control Short to Power
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1. Jump the SCS line with the HDS.
2. Turn the ignition switch to LOCK (0).
3. Disconnect the PCM connectors.
4. Turn the ignition switch to ON (II).
5. Measure the voltage between ignition coil 3P connector terminals No. 3 (Ignition Control) and
body ground.
Fig. 110: Measuring Voltage Between Ignition Coil 3P Connector Terminals No. 3 (Ignition
Control) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 4 V or more?
YES : There is a short to power on the ignition coil control circuit. Find and repair the failure, and then
do the repair verification .
NO : The PCM is malfunctioning. Replace the PCM See PCM UPDATE or PCM REMOVAL AND
INSTALLATION , and then do the repair verification .
11. Check Ignition Coil Control Open Circuit
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1. Jump the SCS line with the HDS.
2. Turn the ignition switch to LOCK (0).
3. Disconnect the PCM connectors.
4. Check for continuity between the ignition coil control terminal at the PCM connector and at the
ignition coil 3P connector terminal No. 3.
Fig. 111: Checking Continuity Between Ignition Coil Control Terminal PCM Connector And
Ignition Coil 3P Connector Terminal No. 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES : The ignition coil control circuit is not open. Go to step 12.
NO : Repair the open circuit between the ignition coil and the PCM, and then do the repair verification .
12. Check Ignition Coil Control Short to Ground
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1. Check for continuity between the ignition coil control terminal at the ignition coil 3P connector
terminal No. 3 and body ground.
Fig. 112: Checking Continuity Between Ignition Coil Control Terminal At Ignition Coil 3P
Connector Terminal No. 3 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES : Repair the short to ground on the ignition coil control wire, and then do the repair verification .
NO : The ignition coil control wiring is OK. Substitute a known good PCM See PCM REMOVAL
AND INSTALLATION or PCM UPDATE , and then do the repair verification .
13. Check Ignition Coil Power Circuit
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1. Measure the voltage between ignition coil 3P connector terminal No. 1 (power) and a known-
good engine ground.
Fig. 113: Measuring Voltage Between Ignition Coil 3P Connector Terminal No. 1 (Power)
And Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage between the ignition coil power terminal and engine ground?
YES : The power circuit is OK. Repair the open circuit between the ignition coil (3P connector terminal
No. 2) and G102, and then do the repair verification .
NO : Repair the open circuit between the ignition coil and the ignition coil relay, and then do the repair
verification .
14. Inspect Ignition Coil
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1. Inspect the ignition coil and spark plug tube for engine oil contamination.
Is the ignition coil covered in engine oil?
YES : Clean the oil from the ignition coil and spark plug tube. REPLACE THE SPARK PLUG TUBE
SEALS IN THE CYLINDER HEAD COVER , and then do the repair verification .
NO : Go to step 15.
15. Exchange Spark Plug and Ignition Coil
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1. Exchange the spark plug and the ignition coil with one from a normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The ignition coil and spark plug are OK. Go to step 17.
NO : There is a failure in the ignition coil or the spark plug. Go to step 16.
16. Exchange Ignition Coil
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1. Exchange the ignition coil on the problem cylinder with a normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The spark plug has a failure. REPLACE THE SPARK PLUG , and then do the repair
verification .
NO : The ignition coil has a failure. REPLACE THE IGNITION COIL , and then do the repair
verification .
17. Check Cylinder Leakage
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1. PERFORM A CYLINDER LEAKAGE TEST .
2. Record your test results in the chart shown below.
ο‘
Fig. 114: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Leakage % Leakage Area
No. 1
No. 2
No. 3
No. 4
%
%
%
%
Does any cylinder have leakage greater than 10%?
YES : If the majority of the air is escaping from exhaust pipe or throttle body, check for tight valve
clearance and adjust each cylinder as needed, then retest. Determine the cause of the cylinder leakage and
repair the engine as needed, and then do the repair verification .
NO : The cylinders are sealing properly. Go to step 18.
18. Check Cylinder Compression
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1. PERFORM A CYLINDER COMPRESSION TEST .
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2. Record your test results in a chart similar to the one shown below.
Fig. 115: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Compression
No. 1
No. 2
No. 3
No. 4
PSI
PSI
PSI
PSI
Highest Reading Lowest Reading Variation
PSI PSI
%
Does the compression vary more than 10% between cylinders, or does any cylinder read below 150 PSI?
YES : The cylinder leakage is normal, but the engine compression is low. Check for each of the
conditions below and repair as needed, and then do the repair verification .
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Incorrect camshaft timing.
A bent (short) connecting rod.
Worn or damaged camshaft lobes.
NO : The engine compression and cylinder leakage is normal. Go to step 19.
19. Exchange Fuel Injector
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1. Exchange the fuel injector from the problem cylinder with one from another cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Do the misfire counts stay at the problem cylinder when the fuel injector is swapped?
YES : The fuel injector is OK. Go to step 20.
NO : The fuel injector is faulty. REPLACE THE FAULTY FUEL INJECTOR , and then do the repair
verification .
20. CKP Pattern Clear/Pattern Learn
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1. Select CRANK PATTERN in the ADJUSTMENT MENU with the HDS.
2. Select CRANK PATTERN CLEAR, and clear the CKP pattern.
3. Select CRANK PATTERN LEARNING with the HDS, and follow the screen prompts.
4. Drive the vehicle under the conditions when the misfire was duplicated.
5. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : Update the PCM with the latest software See PCM REMOVAL AND INSTALLATION or
PCM UPDATE or substitute a known-good PCM See PCM REMOVAL AND INSTALLATION or
PCM UPDATE , and then do the repair verification .
NO : Perform the repair confirmation .
21. Inspect Spark Plug
ο‘
1. Remove the spark plug from the problem cylinder.
ο‘
2. Inspect the spark plug for signs of failure. Also make sure the spark plugs are the correct part
number for the vehicle.
Does the spark plug show any signs of failure or is it not the correct part number?
YES : REPLACE THE SPARK PLUG , and then do the repair verification .
NO : Go to step 22.
22. Inspect Ignition Coil
ο‘
1. Inspect the ignition coil and spark plug tube for engine oil contamination.
Is the ignition coil covered in engine oil?
YES : Clean the oil from the ignition coil and spark plug tube. REPLACE THE SPARK PLUG TUBE
SEALS IN THE CYLINDER HEAD cover, and then do the repair verification .
NO : Go to step 23.
23. Exchange Spark Plug and Ignition Coil
ο‘
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ο‘
1. Exchange the spark plug and the ignition coil with normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The ignition coil and spark plug are OK. Go to step 25.
NO : There is a failure in the ignition coil or the spark plug. Go to step 24.
24. Exchange Ignition Coil
ο‘
ο‘
ο‘
1. Exchange the ignition coil on the problem cylinder with a normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The spark plug has a failure. REPLACE THE SPARK PLUG , and then do the repair
verification .
NO : The ignition coil has a failure. REPLACE THE IGNITION COIL , and then do the repair
verification .
25. Check MAP Sensor Fluctuation
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1. Start the engine, and let it idle until the cooling fans cycle twice.
2. Turn off all engine and electrical loads (AC, radio, lights, etc.).
3. Configure a HIGH-SPEED SNAPSHOT, and select only the MAP SENSOR.
4. Begin displaying live vehicle data on a line graph.
5. Configure the MAP SENSOR line graph range for 1.2 V MAX and 0.8 V MIN.
6. Watch the MAP SENSOR fluctuation. See examples below.
Fig. 116: MAP Sensor Proper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 117: MAP Sensor Improper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine hot?
YES : The intake manifold pressure fluctuation indicates a mechanical engine failure. Go to step 26.
NO : The intake manifold vacuum fluctuation is OK. Go to step 29.
26. Adjust Valve Clearance
ο‘
1. Adjust the valve clearances See VALVE CLEARANCE ADJUSTMENT or VALVE,
SPRING, AND VALVE SEAL REMOVAL AND INSTALLATION , and inspect the camshaft for
excessive wear or grooves.
NOTE:
ECT Sensor 1 must read less than 100 Β° F (38 Β° C) before adjusting
the valve clearance. Short cutting this step may cause incorrect valve
clearance and engine misfire.
ο‘
2. Recheck the MAP Sensor fluctuation at idle.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine hot?
YES : Adjusting the valve clearance did not correct the excessive MAP sensor fluctuation. Go to step 27.
NO : The excessive MAP sensor fluctuation was caused by incorrect valve clearance. Perform the
Repair Confirmation .
27. Check Cylinder Leakage
ο‘
1. PERFORM A CYLINDER LEAKAGE TEST .
2. Record your test results in the chart shown below.
ο‘
Fig. 118: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Leakage Leakage Area
No. 1
No. 2
No. 3
No. 4
%
%
%
%
Does any cylinder have leakage greater than 10 %?
YES : If the majority of the air is escaping from exhaust pipe or throttle body, check for tight valve
clearance and adjust each cylinder as needed, then retest. Determine the cause of the cylinder leakage and
repair the engine as needed, and then do the repair verification .
NO : The cylinders are sealing properly. Go to step 28.
28. Check Cylinder Compression
ο‘
1. PERFORM A CYLINDER COMPRESSION TEST .
ο‘
2. Record your test results in a chart similar to the one shown below.
Fig. 119: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Compression
No. 1
No. 2
No. 3
No. 4
PSI
PSI
PSI
PSI
Highest Reading Lowest Reading Variation
PSI PSI
%
Does the compression vary more than 10 % between cylinders, or does any cylinder read below 150 PSI?
YES : The cylinder leakage is normal, but the engine compression is low. Check for each of the
conditions below and repair as needed, and then do the repair verification .
ο¬
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Incorrect camshaft timing.
A bent (short) connecting rod.
Worn or damaged camshaft lobes.
NO : The engine compression and cylinder leakage is normal. Go to step 29.
29. Exchange Fuel Injector
ο‘
ο‘
ο‘
1. Exchange the fuel injector from the problem cylinder with one from another cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Do the misfire counts stay at the problem cylinder when the fuel injector is swapped?
YES : The fuel injector is OK. All of the failures have been checked for this type of misfire. Go to step 1
in the Problem verification procedure and ensure you selected the correct troubleshooting procedure.
NO : The fuel injector is faulty. REPLACE THE FAULTY FUEL INJECTOR , and then do the repair
verification .
30. Inspect Spark Plug
ο‘
1. Remove the spark plug from the problem cylinder.
ο‘
2. Inspect the spark plug for signs of failure. Also make sure the spark plugs are the correct part
number for the vehicle.
Does the spark plug show any signs of failure or is it not the correct part number?
YES : REPLACE THE SPARK PLUG , and then do the repair verification .
NO : Go to step 31.
31. Check Ignition Coil Spark
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ο‘
ο‘
1. Turn the ignition switch to LOCK (0).
2. Remove the ignition coil from the problem cylinder.
3. Connect a commercially available spark tester between the ignition coil and engine ground.
4. Start the engine with the ignition coil connected.
Does the ignition coil produce a spark?
YES : The ignition coil wiring is OK. Go to step 39.
NO : There is a problem with the ignition coil wiring. Go to step 32.
32. Exchange Ignition Coil
ο‘
ο‘
ο‘
1. Exchange the ignition coil on the problem cylinder with a normally operating cylinder.
2. Connect a commercially available spark tester between the ignition coil and engine ground.
3. Start the engine with the ignition coil connected.
Does the ignition coil produce a spark?
YES : The ignition coil has a failure. REPLACE THE IGNITION COIL , and then do the repair
verification .
NO : There is a problem with the ignition coil circuit. Go to step 33.
33. Check Ignition Coil Power and Ground
ο‘
ο‘
ο‘
1. Disconnect the ignition coil 3P connector from the problem cylinder.
2. Turn the ignition switch to ON (II).
3. Measure the voltage between ignition coil 3P connector terminals No. 1 (power) and No. 3
(ground).
Fig. 120: Measuring Voltage Between Ignition Coil 3P Connector Terminals No. 1 (Power)
And No. 3 (Ground)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES : The ignition coil power and ground circuits are OK. Go to step 34.
NO : There is a problem with the ignition coil power or ground circuit. Go to step 38.
34. Check Ignition Coil Control Short to Power
ο‘
1. Turn the ignition switch to ON (II).
ο‘
2. Measure the voltage between ignition coil 3P connector terminals No. 3 (Ignition Control) and
body ground.
Fig. 121: Measuring Voltage Between Ignition Coil 3P Connector Terminals No. 3 (Ignition
Control) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 4 V or more?
YES : The ignition coil control circuit is shorted to power. Go to step 35.
NO : The ignition coil control circuit is not shorted to power. Go to step 36.
35. Isolate Ignition Coil Control Short to Power
ο‘
ο‘
ο‘
ο‘
ο‘
1. Jump the SCS line with the HDS.
2. Turn the ignition switch to LOCK (0).
3. Disconnect the PCM connectors.
4. Turn the ignition switch to ON (II).
5. Measure the voltage between ignition coil 3P connector terminals No. 3 (Ignition Control) and
body ground.
Fig. 122: Measuring Voltage Between Ignition Coil 3P Connector Terminals No. 3 (Ignition
Control) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there about 4 V or more?
YES : There is a short to power on the ignition coil control circuit. Find and repair the failure, and then
do the repair verification .
NO : The PCM is malfunctioning. Replace the PCM See PCM UPDATE or PCM REMOVAL AND
INSTALLATION , and then do the repair verification .
36. Check Ignition Coil Control Open Circuit
ο‘
ο‘
ο‘
ο‘
1. Jump the SCS line with the HDS.
2. Turn the ignition switch to LOCK (0).
3. Disconnect the PCM connectors.
4. Check for continuity between the ignition coil control terminal at the PCM connector and at the
ignition coil 3P connector terminal No. 3.
Fig. 123: Checking Continuity Between Ignition Coil Control Terminal PCM Connector And
Ignition Coil 3P Connector Terminal No. 3
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES : The ignition coil control circuit is not open. Go to step 37.
NO : Repair the open circuit between the ignition coil and the PCM, and then do the repair verification .
37. Check Ignition Coil Control Short to Ground
ο‘
1. Check for continuity between the ignition coil control terminal at the ignition coil 3P connector
terminal No. 3 and body ground.
Fig. 124: Checking Continuity Between Ignition Coil Control Terminal Ignition Coil 3P
Connector Terminal No. 3 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES : Repair the short to ground on the ignition coil control wire, and then do the repair verification .
NO : The ignition coil control wiring is OK. Substitute a known-good PCM See PCM REMOVAL
AND INSTALLATION or PCM UPDATE , and then do the repair verification .
38. Check Ignition Coil Power Circuit
ο‘
1. Measure the voltage between ignition coil 3P connector terminal No. 1 (power) and a known-
good engine ground.
Fig. 125: Measuring Voltage Between Ignition Coil 3P Connector Terminal No. 1 (Power)
And Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage between the ignition coil power terminal and engine ground?
YES : The power circuit is OK. Repair the open circuit between the ignition coil (3P connector terminal
No. 2) and G102, and then do the repair verification .
NO : Repair the open circuit between the ignition coil and the ignition coil relay, and then do the repair
verification .
39. Inspect Ignition Coil
ο‘
1. Inspect the ignition coil and spark plug tube for engine oil contamination.
Is the ignition coil covered in engine oil?
YES : Clean the oil from the ignition coil and spark plug tube. REPLACE THE SPARK PLUG TUBE
SEALS IN THE CYLINDER HEAD COVER , and then do the repair verification .
NO : Go to step 40.
40. Exchange Spark Plug and Ignition Coil
ο‘
ο‘
ο‘
1. Exchange the spark plug and the ignition coil with normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The ignition coil and spark plug are OK. Go to step 42.
NO : There is a failure in the ignition coil or the spark plug. Go to step 41.
41. Exchange Ignition Coil
ο‘
ο‘
ο‘
1. Exchange the ignition coil on the problem cylinder with a normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The spark plug has a failure. REPLACE THE SPARK PLUG , and then do the repair
verification .
NO : The ignition coil has a failure. REPLACE THE IGNITION COIL , and then do the repair
verification .
42. Check MAP Sensor Fluctuation
ο‘
ο‘
ο‘
ο‘
ο‘
ο‘
1. Start the engine, and let it idle until the cooling fans cycle twice.
2. Turn off all engine and electrical loads (AC, radio, lights, etc.).
3. Configure a HIGH-SPEED SNAPSHOT, and select only the MAP SENSOR.
4. Begin displaying live vehicle data on a line graph.
5. Configure the MAP SENSOR line graph range for 1.2 V MAX and 0.8 V MIN.
6. Watch the MAP SENSOR fluctuation. See examples below.
Fig. 126: MAP Sensor Proper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 127: MAP Sensor Improper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine hot?
YES : The intake manifold pressure fluctuation indicates a mechanical engine failure. Go to step 43.
NO : The intake manifold vacuum fluctuation is OK. Go to step 46.
43. Adjust Valve Clearance
ο‘
1. Adjust the valve clearances See VALVE CLEARANCE ADJUSTMENT or VALVE,
SPRING, AND VALVE SEAL REMOVAL AND INSTALLATION , and inspect the camshaft for
excessive wear or grooves.
NOTE:
ECT Sensor 1 must read less than 100 Β°F (38 Β° C) before adjusting the
valve clearance. Short cutting this step may cause incorrect valve
clearance and engine misfire.
ο‘
2. Recheck the MAP Sensor fluctuation at idle.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine hot?
YES : Adjusting the valve clearance did not correct the excessive MAP sensor fluctuation. Go to step 44.
NO : The excessive MAP sensor fluctuation was caused by incorrect valve clearance. Perform the
Repair Confirmation .
44. Check Cylinder Leakage
ο‘
1. PERFORM A CYLINDER LEAKAGE TEST .
2. Record your test results in the chart shown below.
ο‘
Fig. 128: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Leakage % Leakage Area
No. 1
No. 2
No. 3
No. 4
%
%
%
%
Does any cylinder have leakage greater than 10 %?
YES : If the majority of the air is escaping from exhaust pipe or throttle body, check for tight valve
clearance and adjust each cylinder as needed, then retest. Determine the cause of the cylinder leakage and
repair the engine as needed, and then do the repair verification .
NO : The cylinders are sealing properly. Go to step 45.
45. Check Cylinder Compression
ο‘
1. PERFORM A CYLINDER COMPRESSION TEST .
ο‘
2. Record your test results in a chart similar to the one shown below.
Fig. 129: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Compression
No. 1
No. 2
No. 3
No. 4
PSI
PSI
PSI
PSI
Highest Reading Lowest Reading Variation
PSI PSI
%
Does the compression vary more than 10 % between cylinders, or does any cylinder read below 150 PSI?
YES : The cylinder leakage is normal, but the engine compression is low. Check for each of the
conditions below and repair as needed, and then do the repair verification .
ο¬
ο¬
ο¬
Incorrect camshaft timing.
A bent (short) connecting rod.
Worn or damaged camshaft lobes.
NO : The engine compression and cylinder leakage is normal. Go to step 46.
46. Exchange Fuel Injector
ο‘
ο‘
ο‘
1. Exchange the fuel injector from the problem cylinder with one from another cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Do the misfire counts stay at the problem cylinder when the fuel injector is swapped?
YES : The fuel injector is OK. Go to step 47.
NO : The fuel injector is faulty. REPLACE THE FAULTY FUEL INJECTOR , and then do the repair
verification .
47. CKP Pattern Clear/Pattern Learn
ο‘
ο‘
ο‘
ο‘
ο‘
1. Select CRANK PATTERN in the ADJUSTMENT MENU with the HDS.
2. Select CRANK PATTERN CLEAR, and clear the CKP pattern.
3. Select CRANK PATTERN LEARNING with the HDS, and follow the screen prompts.
4. Drive the vehicle under the conditions when the misfire was duplicated.
5. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : Update the PCM with the latest software See PCM REMOVAL AND INSTALLATION or
PCM UPDATE or substitute a known-good PCM See PCM REMOVAL AND INSTALLATION or
PCM UPDATE , and then do the repair verification .
NO : Perform the Repair Confirmation .
48. Inspect Spark Plug
ο‘
1. Remove the spark plug from the problem cylinder.
ο‘
2. Inspect the spark plug for signs of failure. Also make sure the spark plugs are the correct part
number for the vehicle.
Does the spark plug show any signs of failure or is it not the correct part number?
YES : REPLACE THE SPARK PLUG , and then do the repair verification .
NO : Go to step 49.
49. Check MAP Sensor Fluctuation
ο‘
ο‘
ο‘
ο‘
ο‘
ο‘
1. Start the engine, and let it idle until the cooling fans cycle twice.
2. Turn off all engine and electrical loads (AC, radio, lights, etc.).
3. Configure a HIGH-SPEED SNAPSHOT, and select only the MAP SENSOR.
4. Begin displaying live vehicle data on a line graph.
5. Configure the MAP SENSOR line graph range for 1.2 V MAX and 0.8 V MIN.
6. Watch the MAP SENSOR fluctuation. See examples below.
Fig. 130: MAP Sensor Proper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 131: MAP Sensor Improper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine hot?
YES : The intake manifold pressure fluctuation indicates a mechanical engine failure. Go to step 50.
NO : The intake manifold vacuum fluctuation is OK. Go to step 53.
50. Adjust Valve Clearance
ο‘
1. Adjust the valve clearances See VALVE CLEARANCE ADJUSTMENT or VALVE,
SPRING, AND VALVE SEAL REMOVAL AND INSTALLATION , and inspect the camshaft for
excessive wear or grooves.
NOTE:
ECT Sensor 1 must read less than 100 Β° F (38 Β° C) before adjusting
the valve clearance. Short cutting this step may cause incorrect valve
clearance and engine misfire.
ο‘
2. Recheck the MAP Sensor fluctuation at idle.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine hot?
YES : Adjusting the valve clearance did not correct the excessive MAP sensor fluctuation. Go to step 51.
NO : The excessive MAP sensor fluctuation was caused by incorrect valve clearance. Perform the
Repair Confirmation .
51. Check Cylinder Leakage
ο‘
1. PERFORM A CYLINDER LEAKAGE TEST .
2. Record your test results in the chart shown below.
ο‘
Fig. 132: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Leakage % Leakage Area
No. 1
No. 2
No. 3
No. 4
%
%
%
%
Does any cylinder have leakage greater than 10 %?
YES : If the majority of the air is escaping from exhaust pipe or throttle body, check for tight valve
clearance and adjust each cylinder as needed, then retest. Determine the cause of the cylinder leakage and
repair the engine as needed, and then do the repair verification .
NO : The cylinders are sealing properly. Go to step 52.
52. Check Cylinder Compression
ο‘
1. PERFORM A CYLINDER COMPRESSION TEST .
ο‘
2. Record your test results in a chart similar to the one shown below.
Fig. 133: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Compression
No. 1
No. 2
No. 3
No. 4
PSI
PSI
PSI
PSI
Highest Reading Lowest Reading Variation
PSI PSI
%
Does the compression vary more than 10 % between cylinders, or does any cylinder read below 150 PSI?
YES : The cylinder leakage is normal, but the engine compression is low. Check for each of the
conditions below and repair as needed, and then do the repair verification .
ο¬
ο¬
ο¬
Incorrect camshaft timing.
A bent (short) connecting rod.
Worn or damaged camshaft lobes.
NO : The engine compression and cylinder leakage is normal. Go to step 55.
53. Check Cylinder Leakage
ο‘
1. PERFORM A CYLINDER LEAKAGE TEST .
2. Record your test results in the chart shown below.
ο‘
Fig. 134: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Leakage % Leakage Area
No. 1
No. 2
%
%
No. 3
No. 4
%
%
Does any cylinder have leakage greater than 10%?
YES : If the majority of the air is escaping from exhaust pipe or throttle body, check for tight valve
clearance and adjust each cylinder as needed, then retest. Determine the cause of the cylinder leakage and
repair the engine as needed, and then do the repair verification .
NO : The cylinders are sealing properly. Go to step 54.
54. Check Cylinder Compression
ο‘
1. PERFORM A CYLINDER COMPRESSION TEST .
ο‘
2. Record your test results in a chart similar to the one shown below.
Fig. 135: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Compression
No. 1
No. 2
No. 3
No. 4
PSI
PSI
PSI
PSI
Highest Reading Lowest Reading Variation
PSI PSI
%
Does the compression vary more than 10 % between cylinders, or does any cylinder read below 150 PSI?
YES : The cylinder leakage is normal, but the engine compression is low. Check for each of the
conditions below and repair as needed, and then do the repair verification .
ο¬
ο¬
ο¬
Incorrect camshaft timing.
A bent (short) connecting rod.
Worn or damaged camshaft lobes.
NO : The engine compression and cylinder leakage is normal. Go to step 55.
55. Check Fuel Pressure
ο‘
ο‘
ο‘
1. RELIEVE THE FUEL PRESSURE .
2. ATTACH THE FUEL PRESSURE GAUGE SET AND THE FUEL PRESSURE GAUGE .
3. Locate and record the fuel pressure specification for your vehicle.
Minimum Pressure Maximum Pressure
kPa
kPa
ο‘
4. Start the engine and record the fuel pressure under the conditions the misfire was duplicated.
Fuel Pressure
kPa
Is the fuel pressure within specifications?
YES : The fuel pressure is OK. Go to step 56.
NO : Check for pinched or damaged fuel lines. If OK, replace the fuel tank unit See FUEL TANK
UNIT REMOVAL AND INSTALLATION , and then do the repair verification .
56. Check Fuel Contamination
ο‘
1. Remove the fuel tank unit See FUEL TANK UNIT DISASSEMBLY AND REASSEMBLY or
FUEL TANK UNIT REMOVAL AND INSTALLATION .
ο‘
2. Inspect for evidence of fuel contamination such as diesel fuel, water, rust, or debris.
NOTE:
If the misfire occurred shortly after refueling, the likely cause is poor
fuel quality. The MIL DIST (MIL distance) value in the DATA LIST,
along with the fuel level, can help you make this determination.
Incorrect or contaminated fuel typically affects multiple cylinders. But a problem such as water in
the fuel can cause a single cylinder misfire that occurs randomly.
Is there evidence of fuel contamination?
YES : Replace the fuel filter and then drain/refill the fuel tank with a known-good fuel. Perform the
Repair Confirmation .
NO : The fuel system has no signs of fuel contamination. Go to step 57.
57. Check MAF Sensor g/s
ο‘
1. Locate and record the MAF SENSOR g/s specification for your vehicle. This can be found in
troubleshooting procedure for DTC P0171.
Minimum g/s Maximum g/s Specified RPM
g/s
g/s
g/s
ο‘
2. Ensure the vehicle meets these conditions:
ο¬
ο¬
ο¬
Engine coolant temperature (ECT SENSOR 1) above 176 Β°F (80 Β°C)
Transmission in P or N
All electrical loads off
Current conditions
Signal
Values
Unit
ECT SENSOR 1
ο‘
3. Monitor the ENGINE SPEED in the DATA LIST with the HDS. Raise and hold the engine
speed steady at the specified rpm.
Current conditions
Signal
Values
Unit
ENGINE SPEED
ο‘
4. While holding the rpm steady, check the MAF SENSOR in the DATA LIST.
Current conditions
Signal
Values
Unit
MAF SENSOR
Is the MAF Sensor g/s value within specifications?
YES : The MAF sensor is reading correctly. REPLACE THE FUEL INJECTORS , and then do the
repair verification .
NO : The MAF sensor is not reading correctly. REPLACE THE MAF SENSOR/IAT SENSOR , and
then do the repair verification .
58. Inspect Spark Plug
ο‘
1. Remove the spark plug from the problem cylinder.
ο‘
2. Inspect the spark plug for signs of failure. Also make sure the spark plugs are the correct part
number for the vehicle.
Does the spark plug show any signs of failure or is it not the correct part number?
YES : REPLACE THE SPARK PLUG , and then do the repair verification .
NO : Go to step 59.
59. Inspect Ignition Coil
ο‘
1. Inspect the ignition coil and spark plug tube for engine oil contamination.
Is the ignition coil covered in engine oil?
YES : Clean the oil from the ignition coil and spark plug tube. REPLACE THE SPARK PLUG TUBE
SEALS IN THE CYLINDER HEAD COVER , and then do the repair verification .
NO : Go to step 60.
60. Exchange Spark Plug and Ignition Coil
ο‘
ο‘
ο‘
1. Exchange the spark plug and the ignition coil with normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The ignition coil and spark plug are OK. Go to step 62.
NO : There is a failure in the ignition coil or the spark plug. Go to step 61.
61. Exchange Ignition Coil
ο‘
ο‘
ο‘
1. Exchange the ignition coil on the problem cylinder with a normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The spark plug has a failure. REPLACE THE SPARK PLUG , and then do the repair
verification .
NO : The ignition coil has a failure. REPLACE THE IGNITION COIL , and then do the repair
verification .
62. Exchange Fuel Injector
ο‘
ο‘
ο‘
1. Exchange the fuel injector from the problem cylinder with one from another cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Do the misfire counts stay at the problem cylinder when the fuel injector is swapped?
YES : The fuel injector is OK. Go to step 63.
NO : The fuel injector is faulty. REPLACE THE FAULTY FUEL INJECTOR , and then do the repair
verification .
63. Inspect VTEC System
ο‘
1. PERFORM THE VTEC ROCKER ARM TEST .
Does the engine pass the VTEC rocker arm test?
YES : Go to step 64.
NO : Repair the VTEC system, and then do the repair verification .
64. CKP Pattern Clear/Pattern Learn
ο‘
ο‘
ο‘
ο‘
ο‘
1. Select CRANK PATTERN in the ADJUSTMENT MENU with the HDS.
2. Select CRANK PATTERN CLEAR, and clear the CKP pattern.
3. Select CRANK PATTERN LEARNING with the HDS, and follow the screen prompts.
4. Drive the vehicle under the conditions when the misfire was duplicated.
5. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : Update the PCM with the latest software See PCM REMOVAL AND INSTALLATION or
PCM UPDATE or substitute a known-good PCM See PCM REMOVAL AND INSTALLATION or
PCM UPDATE , and then do the repair verification .
NO : Perform the Repair Confirmation .
65. Inspect Spark Plug
ο‘
1. Remove the spark plug from the problem cylinder.
ο‘
2. Inspect the spark plug for signs of failure. Also make sure the spark plugs are the correct part
number for the vehicle.
Does the spark plug show any signs of failure or is it not the correct part number?
YES : REPLACE THE SPARK PLUG , and then do the repair verification .
NO : Go to step 66.
66. Check Fuel Pressure
ο‘
ο‘
ο‘
1. RELIEVE THE FUEL PRESSURE .
2. ATTACH THE FUEL PRESSURE GAUGE SET AND THE FUEL PRESSURE GAUGE .
3. Locate and record the fuel pressure specification for your vehicle.
Minimum Pressure Maximum Pressure
kPa
kPa
ο‘
4. Start the engine and record the fuel pressure under the conditions the misfire was duplicated.
Fuel Pressure
kPa
Is the fuel pressure within specifications?
YES : The fuel pressure is OK. Go to step 67.
NO : Check for pinched or damaged fuel lines. If OK, replace the fuel tank unit See FUEL TANK
UNIT REMOVAL AND INSTALLATION or FUEL TANK UNIT DISASSEMBLY AND
REASSEMBLY , and then do the repair verification .
67. Check Fuel Contamination
ο‘
1. Remove the fuel tank unit See FUEL TANK UNIT DISASSEMBLY AND REASSEMBLY or
FUEL TANK UNIT REMOVAL AND INSTALLATION .
ο‘
2. Inspect for evidence of fuel contamination such as diesel fuel, water, rust, or debris.
NOTE:
If the misfire occurred shortly after refueling, the likely cause is poor
fuel quality. The MIL DIST (MIL distance) value in the DATA LIST,
along with the fuel level, can help you make this determination.
Incorrect or contaminated fuel typically affects multiple cylinders. But a problem such as water in
the fuel can cause a single cylinder misfire that occurs randomly.
Is there evidence of fuel contamination?
YES : Replace the fuel filter See FUEL TANK UNIT REMOVAL AND INSTALLATION or FUEL
TANK UNIT DISASSEMBLY AND REASSEMBLY and then drain/refill the fuel tank with a known-
good fuel. Perform the Repair Confirmation .
NO : The fuel system has no signs of fuel contamination. Go to step 68.
68. Exchange Fuel Injector
ο‘
ο‘
ο‘
1. Exchange the fuel injector from the problem cylinder with one from another cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Do the misfire counts stay at the problem cylinder when the fuel injector is swapped?
YES : The fuel injector is OK. Go to step 69.
NO : The fuel injector is faulty. REPLACE THE FAULTY FUEL INJECTOR , and then do the repair
verification .
69. Inspect VTEC System
ο‘
1. PERFORM THE VTEC ROCKER ARM TEST .
Does the engine pass the VTEC rocker arm test?
YES : Go to step 70.
NO : Repair the VTEC system, and then do the repair verification .
70. Check for Exhaust Restrictions
ο‘
ο‘
1. Reinstall all removed parts, and reconnect all connectors.
2. Record the MAP SENSOR value while the engine is off.
Current conditions
Signal
Values
Unit
MAP SENSOR
ο‘
3. Start the engine and monitor the ENGINE SPEED and MAP SENSOR in the DATA LIST with
the HDS.
Current conditions
Signal
Values
Unit
MAP SENSOR
ENGINE SPEED
ο‘
4. Raise the engine speed to 3500 rpm and hold the throttle steady.
Does the MAP SENSOR read near atmospheric pressure (engine off value)?
YES : There is a restriction in the exhaust system. Check for catalyst damage and repair as necessary.
Perform the Repair Confirmation .
NO : Go to step 71.
71. CKP Pattern Clear/Pattern Learn
ο‘
ο‘
ο‘
ο‘
ο‘
1. Select CRANK PATTERN in the ADJUSTMENT MENU with the HDS.
2. Select CRANK PATTERN CLEAR, and clear the CKP pattern.
3. Select CRANK PATTERN LEARNING with the HDS, and follow the screen prompts.
4. Drive the vehicle under the conditions when the misfire was duplicated.
5. Monitor these parameters in the DATA LIST:
ο¬
ο¬
ο¬
ο¬
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : Update the PCM with the latest software See PCM REMOVAL AND INSTALLATION or
PCM UPDATE or SUBSTITUTE A KNOWN-GOOD PCM , and then do the repair verification .
NO : Perform the Repair Confirmation .
72. Check MAP Sensor Fluctuation
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1. Start the engine, and let it idle until the cooling fans cycle twice.
2. Turn off all engine and electrical loads (AC, radio, lights, etc.).
3. Configure a HIGH-SPEED SNAPSHOT, and select only the MAP SENSOR.
4. Begin displaying live vehicle data on a line graph.
5. Configure the MAP SENSOR line graph range for 1.2 V MAX and 0.8 V MIN.
6. Watch the MAP SENSOR fluctuation. See examples below.
Fig. 136: MAP Sensor Proper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig. 137: MAP Sensor Improper Signal Waveform
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine cold?
YES : The intake manifold pressure fluctuation indicates a mechanical engine failure. Go to step 73.
NO : The intake manifold vacuum fluctuation is OK. Go to step 76.
73. Adjust Valve Clearance
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1. Adjust the valve clearances See VALVE CLEARANCE ADJUSTMENT or VALVE,
SPRING, AND VALVE SEAL REMOVAL AND INSTALLATION , and inspect the camshaft for
excessive wear or grooves.
NOTE:
ECT Sensor 1 must read less than 100 Β°F (38 Β°C) before adjusting the
valve clearance. Short cutting this step may cause incorrect valve
clearance and engine misfire.
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2. Recheck the MAP Sensor fluctuation at idle.
Does the MAP SENSOR continuously fluctuate 0.04 V or more at idle, no loads, engine cold?
YES : Adjusting the valve clearance did not correct the excessive MAP sensor fluctuation. Go to step 74.
NO : The excessive MAP sensor fluctuation was caused by incorrect valve clearance. Perform the
Repair Confirmation .
74. Check Cylinder Leakage
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1. PERFORM A CYLINDER LEAKAGE TEST .
Does any cylinder have leakage greater than 10 %?
YES : If the majority of the air is escaping from exhaust pipe or throttle body, check for tight valve
clearance and adjust each cylinder as needed, then retest. Determine the cause of the cylinder leakage and
repair the engine as needed, and then do the repair verification .
NO : The cylinders are sealing properly. Go to step 75.
75. Check Cylinder Compression
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1. PERFORM A CYLINDER COMPRESSION TEST .
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2. Record your test results in a chart similar to the one shown below.
Fig. 138: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Compression
No. 1
No. 2
No. 3
No. 4
PSI
PSI
PSI
PSI
Highest Reading Lowest Reading Variation
PSI PSI
%
Does the compression vary more than 10 % between cylinders, or does any cylinder read below 150 PSI?
YES : The cylinder leakage is normal, but the engine compression is low. Check for each of the
conditions below and repair as needed, and then do the repair verification .
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Incorrect camshaft timing.
A bent (short) connecting rod.
Worn or damaged camshaft lobes.
NO : The engine compression and cylinder leakage is normal. Go to step 76.
76. Check Fuel Injector Leak Down
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1. CONNECT THE FUEL PRESSURE GAUGE SET .
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2. Ensure that the fuel shut off valve is on the fuel pump side of the pressure gauge.
Fig. 139: Checking Fuel Injector Leakage Using Pressure Gauge
Courtesy of AMERICAN HONDA MOTOR CO., INC.
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3. Start the engine and then shut it off.
4. Turn the shut off valve 90Β° to isolate the pressure between the fuel injectors and the fuel pressure
gauge.
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5. Record the initial fuel pressure reading.
6. Let the vehicle sit for 10 minutes.
7. Check the fuel pressure.
Does the pressure drop more than 10 PSI within 10 minutes?
YES : The fuel injectors are leaking. REPLACE THE FUEL INJECTORS , and then do the repair
verification .
NO : The fuel injectors are not leaking. Go to step 77.
77. Inspect Spark Plug
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1. Remove the spark plug from the problem cylinder.
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2. Inspect the spark plug for signs of failure. Also make sure the spark plugs are the correct part
number for the vehicle.
Does the spark plug show any signs of failure or is it not the correct part number?
YES : REPLACE THE SPARK PLUG , and then do the repair verification .
NO : Go to step 78.
78. Exchange Spark Plug and Ignition Coil
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1. Exchange the spark plug and the ignition coil with normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The ignition coil and spark plug are OK.
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If you have already performed a cylinder leakage and compression test, go to step 82.
If you have not performed a cylinder leakage and compression test, go to step 80.
NO : There is a failure in the ignition coil or the spark plug. Go to step 79.
79. Exchange Ignition Coil
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1. Exchange the ignition coil on the problem cylinder with a normally operating cylinder.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
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CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay at the problem cylinder?
YES : The spark plug has a failure. REPLACE THE SPARK PLUG , and then do the repair
verification .
NO : The ignition coil has a failure. REPLACE THE IGNITION COIL , and then do the repair
verification .
80. Check Cylinder Leakage
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1. PERFORM A CYLINDER LEAKAGE TEST .
2. Record your test results in the chart shown below.
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Fig. 140: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Leakage % Leakage Area
No. 1
No. 2
No. 3
No. 4
%
%
%
%
Does any cylinder have leakage greater than 10 %?
YES : If the majority of the air is escaping from exhaust pipe or throttle body, check for tight valve
clearance and adjust each cylinder as needed, then retest. Determine the cause of the cylinder leakage and
repair the engine as needed, and then do the repair verification .
NO : The cylinders are sealing properly. Go to step 81.
81. Check Cylinder Compression
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1. PERFORM A CYLINDER COMPRESSION TEST .
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2. Record your test results in a chart similar to the one shown below.
Fig. 141: Identifying Cylinder
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Compression
No. 1
No. 2
No. 3
No. 4
PSI
PSI
PSI
PSI
Highest Reading Lowest Reading Variation
PSI PSI
%
Does the compression vary more than 10 % between cylinders, or does any cylinder read below 150 PSI?
YES : The cylinder leakage is normal, but the engine compression is low. Check for each of the
conditions below and repair as needed, and then do the repair verification .
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Incorrect camshaft timing.
A bent (short) connecting rod.
Worn or damaged camshaft lobes.
NO : The engine compression and cylinder leakage is normal. Go to step 82.
82. Engine Carbon Removal
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1. Perform a top engine cleaning following the product manufacturer's instructions.
2. Drive the vehicle under the conditions when the misfire was duplicated.
3. Monitor these parameters in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Signal
Values
Unit
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Did the misfire counts stay?
YES : The carbon removal procedure did not correct the misfire. REPLACE THE FUEL INJECTORS ,
and then do the repair verification .
NO : The carbon removal procedure corrected the misfire. Perform the Repair Confirmation .
REPAIR VERIFICATION
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1. Reinstall all removed parts, and reconnect all connectors.
2. Turn the ignition switch to ON (II).
3. Reset the PCM with the HDS See HOW TO TROUBLESHOOT THE A/T SYSTEM or HOW
TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS .
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4. Clear the CKP pattern with the HDS See HOW TO TROUBLESHOOT THE A/T SYSTEM or
HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS .
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5. DO THE PCM IDLE LEARN PROCEDURE .
6. Do the CKP pattern learn procedure See HOW TO TROUBLESHOOT THE FUEL AND
EMISSIONS SYSTEMS or HOW TO TROUBLESHOOT THE A/T SYSTEM .
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7. Drive the vehicle under the conditions that you noticed the misfire while monitoring these parameters
in the DATA LIST:
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CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Current conditions
Values Unit
Signal
CYL1 MISFIRE
CYL2 MISFIRE
CYL3 MISFIRE
CYL4 MISFIRE
Do any of the cylinders display misfire counts?
YES : The engine is still misfiring. Go to step 1 in the Problem verification procedure and ensure that you
selected the correct troubleshooting procedure.
NO : The misfire problem has been fixed. Clear the DTC.
DTC P0326: KNOCK SENSOR MALFUNCTION
Fig. 142: DTC Troubleshooting Flow Chart (P0326)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
NOTE:
Before you troubleshoot, record all freeze data and any on-board snapshot, and
review the general troubleshooting information See HOW TO TROUBLESHOOT
THE A/T SYSTEM or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS
SYSTEMS .
DTC Description
Confirmed DTC Pending DTC Freeze Frame
P0326 KNOCK SENSOR MALFUNCTION
1. Problem verification:
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1. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS See HOW TO TROUBLESHOOT THE A/T SYSTEM or
HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS .
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3. Turn the ignition switch to LOCK (0).
4. Start the engine. Hold the engine speed at 2, 000 rpm or more without load (in P or N) for at least
2024 Honda CR-V Owner's Manual
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