Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. Only use this test to diagnose:

• Ignition system.
• Fuel pressure.
• Fuel injectors.
• Engine vacuum system.
• Evaporative system.
• Canister purge solenoid.
• Internal engine wear.

Fig 1: Identifying CKP Sensor & Crankshaft Wheel

1. 1) Check Possible Cause Of Misfire
   
   If vehicle runs out of fuel, a trouble code may be stored in PCM memory. Ensure vehicle has not recently run out of fuel. Clear PCM memory and repeat QUICK TEST  if necessary. If vehicle has not recently run out of fuel, go to next step.
2. 2) Check Crankshaft Pulley
   
   On models equipped with crankshaft pulley-mounted pulse ring, check crank pulley and pulse ring for damage or looseness. On models not equipped with crankshaft pulley-mounted pulse ring, remove front cover if necessary. Check crank pulley and pulse ring for damage or looseness. On all models, repair or replace as necessary. If no faults are found, go to next step.
3. 3) Check For Continuous DTCs
   
   Check for other non-misfire Continuous Memory DTCs which could cause the misfire DTC. If any other Continuous Memory DTCs are present, service as necessary. Disregard misfire DTCs at this time. If no other Continuous Memory DTCs are present, go to next step.
4. 4) Check For KOEO DTCs
   
   If any KOEO DTCs are present, service as necessary. Disregard misfire DTCs at this time. If any other DTCs are present, perform appropriate CIRCUIT TEST . If no KOEO DTCs are present, check spark plugs and spark plug wires. If spark plugs and spark plug wires are okay, go to next step.
5. 5) Check For KOER DTCs
   
   If any KOER DTCs except P1131, P1137, P1151 or P1157 are present, service as necessary. Disregard misfire DTCs at this time. If KOER DTCs P1131, P1137, P1151 or P1157 are present, go to step 8). If no KOER DTCs are present, go to next step (models equipped with Differential Pressure Feedback (DPF) EGR system) or go to step 8) (models not equipped with DPF EGR system).
6. 6) Check/Compare PID Values
   
   Turn ignition and all accessories off. Ensure engine is warmed to normal operating temperature. Turn ignition on. Using scan tester, select and record DPFEGR PID voltage. Start engine and allow to idle. Record DPFEGR PID voltage. If both DPFEGR PID voltage values are within .15 volt of each other, go to step 8). If DPFEGR PID voltages are not within .15 volt of each other, go to CIRCUIT TEST HE , step 100).
   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 8). No test procedures have been omitted.
7. 8) Check Fuel Injector & Circuit Resistance
   
   Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00959), leaving PCM disconnected. Measure and record resistance between suspected fuel injector test pin and test pin No. 71 and 97 at breakout box. See MISFIRE TROUBLE CODES  table for injector test pin identification. If resistance is 11-18 ohms, go to step 9). If resistance is not 11-18 ohms, go to CIRCUIT TEST H , step 56).
8. 9) Check Fuel Injector Drive Signal
   
   With ignition off, connect PCM to breakout box. Connect a non-powered 12-volt test light between test pin No. 71 or 97 and suspect fuel injector test pin at breakout box. Crank or start engine. If test light glows dimly, system is operating properly. Go to next step. If test light does not glow dimly (no light/bright light), replace PCM.
9. 10) Check Fuel Pressure
   
   Turn ignition off. Release fuel pressure. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Install fuel pressure gauge. Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. Note fuel pressure. If fuel pressure is as specified, go to next step. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is not as specified, check and repair fuel system as necessary.
10. 11) Check System Ability To Hold Fuel Pressure
    
    Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. Check for fuel leaking from around fuel injectors, fuel pressure regulator and fuel hoses. Repair as necessary. Turn ignition off and note fuel pressure gauge reading. If fuel pressure remains within 5 psi (35 kPa) of specification for one minute, go to next step. If fuel pressure does not remain within 5 psi (35 kPa) of specification for one minute, check fuel system and repair as necessary.
11. 12) Check Fuel Injector Flow & Leakage
    
    Turn ignition off. Use Rotunda injector tester from Fuel Tester Kit (113-00114) to flow test fuel injectors. Follow injector tester instructions. If flow rate for each fuel injector is okay, go to step 20). If flow rate for any fuel injector is not okay, clean or replace defective fuel injector. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.
12. 20) Check Vacuum System
    
    Inspect all vacuum hoses for kinks or damage. Ensure all vacuum connections are clean and tight. Repair as necessary. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS. If vacuum system is okay, go to next step.
    NOTE: The misfire monitor can be affected by the evaporative emission system.
13. 21) Check Evaporative Emission System
    
    Inspect carbon canister for fuel saturation. Replace carbon canister if canister contains liquid fuel. If carbon canister is okay, go to next step.
14. 22) Pressure Test Evaporative System
    
    Using Rotunda Evaporative Emission System Tester (134-00056), pressure test evaporative system starting at EVAP service port (if equipped) then at fuel filler cap. Follow evaporative emission system tester instructions. If evaporative emission system holds pressure, go to next step. If system does not hold pressure, isolate fault and repair as necessary. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS.
15. 23) Check Vacuum In Evaporative System
    
    Inspect vacuum hoses between engine and carbon canister for restrictions or damage. Ensure all vacuum connections are clean and tight. Check fuel tank vent system blockage. Repair as necessary. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS. If no faults are found, go to step 26).
16. 24) Check EVAP Canister Purge Valve
    
    Turn ignition off. Disconnect EVAP Canister Purge Control Valve (CPCV). EVAP CANP is located in right side of engine compartment, next to A/C accumulator. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect a jumper wire between positive battery terminal and VPWR (Red wire) terminal at EVAP CANP wiring harness connector. Connect another jumper wire between ground and EVAP CPCV (Gray/Yellow wire) terminal at EVAP CPCV wiring harness connector. Connect a vacuum pump to manifold side of EVAP CPCV and apply 16 in. Hg. With battery voltage applied, EVAP CPCV should open and pass air freely. If EVAP CPCV functions as specified, go to next step. If EVAP CPCV does not function as specified, replace EVAP CPCV. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS.
17. 25) Check Engine Condition
    
    Inspect engine for obvious faults. Ensure compression is okay. Check PCV system for restrictions or leaks. Repair as necessary. If no faults can be found, misfire trouble code is intermittent. Go to CIRCUIT TEST Z , step 50).
18. 26) Check EVAP Canister Purge Control Valve (CPCV) Housing
    
    Turn ignition off. Ensure vehicle is at room temperature. Connect vacuum pump to fuel vapor port at EVAP CPCV and apply 16 in. Hg. If vacuum holds, go to next step. If vacuum releases, replace EVAP CPCV.
19. 27) Check For Filter Contamination
    
    Disconnect hose from vacuum input port of EVAP CPCV. Connect vacuum pump to EVAP CPCV vacuum input port and apply 10-15 in. Hg. If little or no vacuum is lost, service EVAP CPCV filter. If filter is okay, replace EVAP CPCV. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS. If vacuum is not as specified, go to step 25).
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 27) to step 30). No test procedures have been omitted.
20. 30) Check For Additional Misfire DTCs
    
    If any DTCs except P0300 are present, go to step 1). If no other DTCs are present, go to next step.
21. 31) Check For Continuous DTCs
    
    If Continuous Memory DTCs are present, service DTCs as necessary. If no other misfire DTCs are present, go to next step.
22. 32) Check/Compare PID Values
    
    Turn ignition and all accessories off. Ensure engine is warmed to normal operating temperature. Turn ignition on. Using scan tool, select DPFEGR PID from PID/DATA monitor menu. Record PID voltage. Start engine and allow to idle. Again, record DPFEGR PID voltage. If both PID voltage values are within .15 volt of each other, go to step 40) (models with Hall Effect type camshaft position sensor) or go to step 41) (models with variable reluctance type camshaft position sensor). If DPFEGR PID voltage is not as specified, go to CIRCUIT TEST HE , step 100).
    NOTE: Hall Effect type camshaft position sensor has a 3-pin connector. Variable reluctance type camshaft position sensor has a 2-pin connector.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 32) to step 40). No test procedures have been omitted.
23. 40) DTC P1309
    
    This fault indicates misfire detection monitor malfunction. Turn ignition and all accessories off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00959), leaving PCM disconnected. Connect DVOM between test pin No. 85 and test pin No. 51 or 103 at breakout box. Using starter, bump engine in short bursts for at least 10 revolutions. DO NOT allow engine to start. If voltage switches from less than 2 volts to more than 8 volts, check CMP sensor for correct installation. If sensor is correctly installed, replace PCM. If voltage does not switch from less than 2 volts to more than 8 volts, replace CMP sensor. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS.
24. 41) Check CMP Sensor Output
    
    Turn ignition and all accessories off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00959). Connect PCM to breakout box. Connect DVOM between test pin No. 85 and test pin No. 51 or 103 at breakout box. Start engine and vary engine speed. If A/C voltage varies more than .1 volt, check CMP sensor for correct installation. If sensor is correctly installed, replace PCM. If voltage does not vary more than .1 volt, replace CMP sensor. Perform MISFIRE MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES  under ADDITIONAL SYSTEM FUNCTIONS.