Circuit/System Testing
- Test the MAP Sensor for being shifted, stuck, skewed, and for correct vacuum supply. Refer to Manifold Absolute Pressure Sensor Diagnosis
.
- Inspect for a vacuum leak between the EGR valve and the intake manifold.
- Inspect the exhaust system for leaks, restrictions, and for modification of 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.