Questions and Answers

Pinging Cadillac Q. I have a 1991 Cadillac Seville with a 4.9 liter engine, front wheel drive that has 93,000 miles on it. It has a ping at low speeds, such as taking off at normal acceleration from stops. This ping does not start until after engine is warmed up. And does not ping at high rpms. I have replaced EGR sensor, plugs, had car tuned by repair shop, I have checked different sensors and all seem to be working.

I always put premium fuel in and also have been putting in an octane buster, but still pings. Also there is no indicator on dash that anything is wrong. Please, please, please help!!!!!

Mac

A. You might have a clogged EGR passage in the intake manifold. In addition to recirculating exhaust gas to lower emissions, it also lowers the combustion chamber temperature to prevent detonation, or pinging as it's most commonly referred to as.

Another possibility is a bad knock sensor that detects the detonation and sends a signal to the BCM to retard the timing to eliminate it. The sensor can be tested by a technician with a scan tool.

Additional Information provided courtesy of ALLDATA