Test Hd: Misfire Monitor: Testing

NOTE: For additional testing information, see DIAGNOSTIC AIDS and DTC DESCRIPTIONS .

1) DTC P0300. P0301, P0302, P0303, P0304, P0305 Or P0306: Check Possible Cause Of Misfire
If vehicle runs out of fuel, a DTC may be stored in PCM memory. If vehicle has recently run out of fuel, clear PCM memory and retest system. If vehicle has not recently run out of fuel, go to next step.

NOTE: When DTCs are present, always diagnose lowest numbered DTC first.

2) Check For DTCs
Turn ignition off. Connect scan tool to DLC. Retrieve DTCs and view freeze frame data. If only misfire DTCs are present, go to next step. If any lower number DTCs are present along with misfire DTCs, service lower number DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, fault may be intermittent. Go to TEST Z , step 1), or go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - VILLAGER article.

3) Check Ignition System

Inspect ignition wires for cracking and arcing. Using DVOM, measure resistance of wires. Ignition wire resistance should be 7 k/ohms per foot. Inspect distributor cap and rotor for carbon tracking, cracks or other damage. Remove spark plugs and inspect for deposits and wear. Replace components as necessary and repeat QUICK TEST . If ignition components are okay, go to next step.

NOTE: Disconnecting PCM erases all DTCs and freeze frame information from PCM memory. Record all DTCs and freeze frame data prior to disconnecting PCM.

4) Check Resistance Of Injector(s) & Circuit(s)
Turn ignition off. Disconnect PCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance between suspect injector signal circuit (INJ1-6) and KAPWR circuit at PCM connector. See HO2S, HTR, INJ1-6 & KAPWR CIRCUIT IDENTIFICATION table. See Figure. If resistance is 10-14 ohms, go to next step. If resistance is not 10-14 ohms, repair open in injector signal circuit or replace injector as necessary. See WIRING DIAGRAMS article.

5) Check For Rich Or Lean System Indication

Reconnect all electrical connections. Turn ignition off. Using scan tool, enter GENERIC functions mode. Access Short Term Fuel Trim PID from PID/DATA MONITOR & RECORD menu. Start engine and warm to normal operating temperature. If Short Term Fuel Trim PID is a positive value, system is indicating lean condition. Go to next step. If Short Term Fuel Trim PID is a negative value, go to step 7). If Short Term Fuel Trim PID is about zero percent, go to step 10).

6) Check Vacuum System

Visually inspect all vacuum hoses for kinks or damage. Check for proper hose routing. Ensure all vacuum connections are clean and tight. Repair or replace as necessary. If vacuum system is okay, go to next step.

7) Check Fuel Delivery System

Go to TEST HC , step 1) and perform fuel delivery system diagnostic procedure. Repair as necessary. If fuel delivery system is okay, go to next step.

NOTE: The following procedure does not require matching of injector color with flow gauge band color.

8) Check Injectors For Leakage
Turn ignition off. Release fuel system pressure. Remove fuel rail assembly from intake manifold (leave hoses and injectors attached). Turn ignition on (do not crank engine). If any injector leakage is observed, replace or clean leaky injector. Repeat QUICK TEST . If no injector leakage is observed, go to next step.

9) Check EVAP System (Federal & California Emissions)

Go to TEST HX and perform EVAP system diagnostic procedures. Repair as necessary. If EVAP system is okay, go to next step.

NOTE: This step will determine if any base engine concerns may have caused misfire DTCs or driveability problem.

10) Check Engine Mechanical Condition
Perform the following tests to evaluate basic engine integrity:
- Perform compression test.
- Perform dynamic valve train analysis.
- Check PCV system.
- Check for vacuum leaks.
Repair any mechanical problem(s) as necessary. If engine is in good mechanical condition, fault may be intermittent. Go to TEST Z , step 1), or go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - VILLAGER article.