4.6 v8

sms4

1994 cougar 4.6 v8. tuned-up,75k miles,stock except for throttle-body. pings on 87 octane-why? wasn't this car designed to fun on this octane?

bnormann

...it may develop carbon deposits that will retain enough heat to ignite the fuel-air mixture prematurely. Of course, this is only one of 10,000 reasons for pre-ignition, so YMMV.

Bruce

corlt1

I have a 4.6L V8 in a 94 T-Bird that also pinged on everything but premium. After an alternator failure set a Service Engine Soon light, the SES light came back on a few weeks later. The dealer asked me why I run 93 octane premium fuel when it's supposed to run off 87 octane regular. I explained, "To avoid the ping". The dealer downloaded a new program into the ECM computer and it's been running fine on 87 regular for the past few years without a hint of ping. On the bad side, I don't think the engine idles as smooth as it did before and the wide open throttle power is not as strong as it was before, either.