'93 JGC 318 Engine Ping Problem

Dick did pass the time by typing:

Generally a lean mixture or hot spot.

Your describing "detonation under load" which is usually fuel related. so my guess is clogged fuel filter, low fuel pressure/flow, or too low of an octane/bad gas, and sometimes sparkplugs if your running to high of a heat range or your picking up crossfire. How old is your filter?

Crapoline:

Detonation/pinging is often caused by a carbon build-up inside the combustion chambers. The fastest/easiest/best way to get rid of the carbon is to use an old mechanic's technique. Slowly (SLOWLY!!!) trickle around 16 ounces of water into the air intake (carb or throttle body) with the engine running. By slow, I mean it should take around two minutes to drain the container. Be sure too to keep good control on the container to avoid dumping the contents too quickly which could cause hydrolock/engine damage.

This technique is VERY/COMPLETELY effective at getting rid of the carbon deposits. The carbon causes the pinging by continuing to glow after the combustion stroke which then prematurely ignites the air-fuel mixture during the next combustion stroke.

Jerry

DougW wrote:

I buy all my gas from Costco, and never have any problem with our other car. They get gas delivery almost every day, so I know it is fresh. Fuel filter older than I thought. Major tune was in 1999 at

Thanks Jerry. I'll give that a try before I get a tune-up. Don't want to pay the Jeep dealer to decarbonize if I can help it.

Dick

Look at the EGR circuit