Possible Causes & Corrections
WARNING: This page is about a different car, the 2003 Pontiac Montana, 2003 Oldsmobile Silhouette, and 2003 Chevrolet Venture. However, it is still accessible from the selected car via links, so may be relevant.
Check the following items:
- Search for bulletins.
- Test Engine Coolant Temperature (ECT) sensor for being shifted in value. Connect a scan tool and compare engine coolant temperature with Intake Air Temperature (IAT) on a cold engine. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L MONTANA, SILHOUETTE & VENTURE article. The ECT and IAT should be within 5°F (3°C) of each other. Test resistance of ECT sensor if temperature is out of range with IAT sensor.
- Monitor the 24X crank sensor and CMP sensor signal present parameters on a scan tool. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L MONTANA, SILHOUETTE & VENTURE article. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Test all CKP sensor "A" and CMP sensor circuits for intermittents.
- Monitor the 3X crank sensor parameter on the scan tool. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L MONTANA, SILHOUETTE & VENTURE article. If the 3X crank sensor parameter is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open or shorted, they may not set a DTC immediately, but are capable of causing driveability complaints.
- Inspect Mass Air Flow (MAF) sensor for proper installation and conditions. A MAF sensor with a damaged honeycomb may cause a hard start.
- Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the MAF sensor and the throttle body.
- Using a scan tool, test Idle Air Control (IAC) operation. Command engine speed to 1500 RPM and back to the starting RPM. If engine RPM does not change when commanded, diagnose IAC circuit.
- Inspect EGR system for proper sealing/connections and operation.
- Test fuel system circuits for proper operation. Refer to Fuel Pump Electrical Circuit Diagnosis in FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L MONTANA, SILHOUETTE & VENTURE article.
- Test for low fuel pressure. Refer to FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L MONTANA, SILHOUETTE & VENTURE article.
- Test for faulty fuel injectors. Refer to FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L MONTANA, SILHOUETTE & VENTURE article.
- Inspect for fuel contamination.
- Inspect for proper ignition voltage output using Spark Tester (J-26792).
- If spark is not present at the coils, inspect for 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.
- Excessive oil in combustion chamber.
- Low cylinder compression.
- For incorrect basic engine parts, such as cylinder heads, camshaft, valve train components, pistons, etc.