Hesitation, Sag Or Stumble: Sensor/System
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
- Monitor the Heated Oxygen Sensors (HO2S). The HO2S should respond quickly to different throttle positions. If not, check the HO2S for silicone or other contaminants from fuel or use of improper RTV sealant. The sensors may have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage, rich exhaust indication. The Powertrain Control Module (PCM) reduces the amount of fuel delivered to the engine, causing a severe driveability condition.
- Monitor the 24X crank sensor and the Camshaft Position (CMP) sensor signal present parameters on the scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all Crankshaft Position (CKP) "A" and CMP sensor circuits for intermittents.
- Check the CKP sensor "B" for an internal short. See ELECTRONIC IGNITION SYSTEM DIAGNOSIS under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
- Check the Throttle Position (TP) sensor and related wiring.
- Check the Mass Airflow (MAF) sensor and related wiring. Check the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the MAF sensor and the throttle body.
- Check the Exhaust Gas Recirculation (EGR) system for proper operation. See EXHAUST GAS RECIRCULATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.