1998 Ford F-150 Pinging Knock
Suggested Repair
With no check engine light, check engine compression and inspect all vacuum hoses, pipes, and connectors for leaks or damaged rubber. Pinging is often related to the EGR system or deposits in the intake manifold and on the intake valves. The door-ajar light is a separate issue; clean and work the door latch switches with electrical contact cleaner.
Conversation Summary
A 1998 Ford F-150 5.4L makes a constant pinging or knocking noise after shifting into fourth gear around 50-55 mph and 1750-2250 rpm. There is no check engine light. The expert said pinging is commonly tied to the EGR system or a dirty intake manifold and valves, and recommended a compression test plus inspection of vacuum hoses and connectors. A stuck door-ajar light was treated as a separate dirty door-switch issue.
