Possible Causes & Corrections

Check the following items:

• Search for bulletins.
• Observe the owner's driving habits. Is the A/C on full time and defroster mode on? Are the tires at the correct pressure? Are excessively heavy loads being carried? Is acceleration too much, too often?
• Test the fuel system circuits for proper operation. Refer to Fuel Pump Electrical Circuit Diagnosis under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L AZTEK & RENDEZVOUS article.
• Test for low fuel pressure. Refer to FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article.
• Test for faulty fuel injectors. Refer to FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L AZTEK & RENDEZVOUS article.
• Inspect for fuel contamination.
• Ensure each injector harness is connected to the correct injector/cylinder.
• Inspect for fuel in the pressure regulator vacuum hose.
• Observe the 24X crank sensor and CMP sensor signal parameters on scan tool. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. If both are not responding, check the sensor feed circuit. Both sensors use a common feed circuit.
• Inspect air intake system and crankcase for air leaks.
• Inspect air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the MAF sensor and throttle body.
• Inspect for proper operation of the speedometer.
• Inspect for proper ignition voltage output using Spark Tester (J-26792).
• If spark is not present at the coils, inspect coils for cracks, carbon tracking/arcing, or a resistance value outside the specified range (5000-8000 ohms). Check spark plug wires for signs of arcing, crossfiring, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range (3000 ohms per foot). Check for defective ignition module, ignition system wiring, loose ignition module feed or ground connection, or damaged system wiring.
• Remove spark plugs and inspect for fouled plugs, cracks, wear, improper gap, burned or damaged electrodes, improper heat range or reach.
• If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
• Inspect engine coolant for correct level.
• Inspect for incorrect or faulty engine thermostat.
• Check engine compression. Refer to MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article. Low compression can be caused by sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms or broken valve springs. Check for excessive oil in combustion chamber, which can be caused by leaking valve seals.
• For incorrect basic engine parts such as camshaft, cylinder heads, pistons, etc.
• Test the Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
• Inspect exhaust system for possible restriction. Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. Inspect for possible plugged catalytic converter.