Detonation, Spark Knock
- Check for overheating conditions. Check ignition timing. Check EGR valve operation. Inspect MAP sensor for restrictions in MAP hose or throttle body MAP port.
- Check PROM for correct application. Check fuel pressure. Fuel pressure should be a steady 9-12 psi (.6-.8 kg/cm2 ) in all speed ranges. If fuel pressure is not within specification, see appropriate A-4 FUEL SYSTEM DIAGNOSIS CHART in COMPUTERIZED ENGINE CONTROL section.
- Check transmission for proper operation. Check for loose intake manifold bolts. Check for correct spark plugs. If condition still exists, vehicle may require use of high octane gasoline.