Possible Cause & Correction

Check the following items:

• Check for incorrect valve timing, bent push rods, broken valve springs or worn camshaft lobes.
• Check for sticking or leaking valves.
• Check EGR valve for leaking base gasket or valve hanging open.
• Check for engine vacuum leaks and/or engine not tuned to specifications.
• Check ignition module ground and power feed circuits for poor or loose connections.
• Check air induction system for restrictions or air leaks. Also check for air leaks between Mass Airflow (MAF) sensor and throttle body. Check MAF sensor for proper operation.
• Check fuel injectors. Perform injector balance test. See FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.2L CTS article.
• Check fuel system. See FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.2L CTS article.
• Using Spark Tester (J-26792), check available output voltage of ignition coil.
• Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits.
• Check for proper Crankshaft Position (CKP) and Camshaft Position (CMP) sensor resistance.
• Check ignition system for faulty ground and power feed circuits.
• Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See RESTRICTED EXHAUST  .
• Check intake and exhaust manifold passages for casting flash.
• Check harmonic balancer interrupter rings for missing, broken or bent vanes.
• Check for a low engine coolant level.
• Check the engine thermostat for the correct operation and heat range.
• Test the Torque Converter Clutch (TCC).
• Check the charging system. A bad diode in the alternator can allow A/C noise to enter the electrical system. This may affect the engine controls system operation.
• Check the automatic transmission manual shift shaft switch assembly circuit and be sure the scan tool indicates the vehicle is in a drive gear.