Circuit/System Testing
- Test the MAP Sensor for being shifted, stuck, skewed, and for correct vacuum supply. Refer to Manifold Absolute Pressure (MAP) Sensor Diagnosis
.
- Inspect for a vacuum leak between the exhaust gas recirculation (EGR) valve and the intake manifold.
- Inspect the exhaust system for leaks, restrictions, and for modification of original equipment manufacture (OEM) parts.
- Remove the EGR valve and inspect for the following:
- cracks
- heat distress
- pintle for corrosion
- EGR Valve Passages for restriction
- EGR passage in the intake manifold for carbon buildup, casting flash or other restriction
- If a condition with the EGR valve is identified, replace the EGR Valve.
- Inspect the engine for correct valve timing and lift or for other conditions that might affect engine vacuum source.