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 is equipped with crankshaft pulley-mounted pulse ring, go to next step. If vehicle is not equipped with crankshaft pulley-mounted pulse ring, go to step 3).
2. 2) Check Crankshaft Pulley  Turn ignition off. Remove front cover if necessary. Check crank pulley and pulse ring for damage or looseness. Repair or replace as necessary. If no faults are found, go to next step.
3. 3) Check For Continuous DTCs  If continuous codes are present, service as necessary. Disregard misfire codes at this time. If no other misfire codes are present, go to next step.
4. 4) Check For KOEO DTCs  If any KOEO DTCs are present, service as necessary. Disregard misfire codes at this time. If any other DTCs are present, proceed to 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 or P1151 are present, service as necessary. Disregard misfire codes at this time. If KOER DTCs P1131 or P1151 are present, go to step 8). If no KOER DTCs are present, check spark plugs and spark plug wires. If spark plugs and spark plug wires are okay, go to next step.
6. 6) Check/Compare PID Values  Turn ignition and all accessories off. Connect scan tester to DLC. Ensure engine is warmed to operating temperature. Turn ignition on. Using scan tester, access and record DPFEGR PID. Start engine and allow to idle. Record DPFEGR PID. If both DPFEGR PID voltage values are within 0.15 volts of each other, go to step 8). If DPFEGR PID voltage is not as specified, 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 pins for damage and repair if necessary. Install EEC-V 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. If resistance is 11-18 ohms, go to step 9). If resistance is not 11-18 ohms, go to step 56) under CIRCUIT TEST H .
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 correctly. Go to next step. If test light does not glow dimly (no light/bright light), replace PCM and repeat QUICK TEST.
9. 10) Check Fuel Pressure  Turn ignition off. Release fuel pressure. 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. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST HC .
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 if necessary. Turn ignition off. Turn ignition on and note fuel pressure gauge reading. If fuel pressure remains at specification for one minute, go to next step. If fuel pressure does not remain at specification for one minute, go to step 3) under CIRCUIT TEST HC .
11. 12) Check Fuel Injector Flow & Leakage  Turn ignition off. Use Rotunda Injector Tester (113-00001) to flow test fuel injectors. If flow rate for each fuel injector is okay, go to step 20). If flow rate for any fuel injector is not okay, replace defective fuel injector and repeat QUICK TEST.
    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 or replace as necessary. 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. Replace carbon canister if it contains liquid fuel. If carbon canister is okay, go to next step.
14. 22) Pressure Test Evaporative System  Remove vapor line from canister and install vacuum tee. Connect a pressure gauge to one side of tee and low pressure air pump to other side of tee. Apply 0.75 psi (5.2 kPa). If evaporative emission system holds pressure, reconnect vapor line and go to next step. If system does not hold pressure, isolate fault and repair as necessary.
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. Repair or replace as necessary. If system is okay, go to next step for vehicles with EVAP canister purge solenoid, or step 26) for vehicles equipped with Vapor Management Valve (VMV).
16. 24) Check Canister Purge Solenoid (CANP)  Turn ignition off. Disconnect CANP solenoid wiring harness connector. Inspect connector for damaged pins and repair as necessary. Using jumper wire, apply 12 volts to VPWR (Red wire) terminal of CANP wiring harness connector. Connect CANP (Gray/Yellow wire) terminal to ground. Connect vacuum pump to manifold side of CANP solenoid and apply 16 in. Hg. When 12 volts is applied, solenoid should open and pass air freely. Replace solenoid if it does not function correctly. If solenoid does function correctly, go to next step.
17. 25) Check Engine Condition  Inspect engine for obvious faults. Ensure compression is even and within specification. Check PCV system for restrictions or leaks. Repair or replace as necessary. If no faults can be found, misfire trouble code is intermittent. Go to CIRCUIT TEST Z .
18. 26) Check Vapor Management Valve (VMV) Housing  Turn ignition off. Ensure vehicle is at room temperature. Connect vacuum pump to fuel vapor port of VMV and apply 16 in. Hg. If vacuum is held, go to next step. If vacuum is not held, replace VMV and repeat QUICK TEST.
19. 27)  Leave ignition off. Disconnect hose from vacuum input port of VMV. Connect vacuum pump to VMV vacuum input port and apply 10-15 in. Hg. If little or no vacuum is lost, service VMV filter. If filter is okay, replace VMV. Repeat QUICK TEST. 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 codes are present, service as necessary. If no other misfire codes are present, go to next step.
22. 32) Check/Compare PID Values  Turn ignition and all accessories off. Connect scan tester to DLC. Ensure engine is warmed to operating temperature. Turn ignition on. Using scan tester, access and record DPFEGR PID. Start engine and allow to idle. Record DPFEGR PID. If both DPFEGR PID voltage values are within 0.15 volts of each other, go to step 8). If DPFEGR PID voltage is not as specified, go to CIRCUIT TEST HE , step 100).
    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 pins for damage and repair if necessary. Install EEC-V Breakout Box (014-00959), leaving PCM disconnected. Connect DVOM between test pins No. 85 and No. 51 or 103. Using starter, bump engine in short bursts for at least 10 revolutions. DO NOT allow engine to start. If voltage switches from below 0.2 volts to over 8.0 volts, check CMP sensor for correct installation. If sensor is correctly installed, replace PCM and repeat QUICK TEST. If voltage does not switch from below 0.2 volts to over 8.0 volts, replace CMP sensor and repeat QUICK TEST.