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Originally Posted by gtrz2
I have a '91 S-10, 2.8 L. with 148 k miles. I've had it about 3 yrs now
and the pinging while accelerating has grown and grown. It's pretty bad
now and I'm thinking it might need a valve job. The enging runs really
good besides, no other problems. Since I've owned it I've replaced the
plugs, wires, and cap. I've taken it to 2 different garages for the problem
in the past. One place did some kind of super fuel system cleaning, that
did not help. The other place (cleaned) my oxygen sensor, he also said
he thought it was running lean, but that didn't help too much either. One
other thing, on the highway if I have it up to 75 or so it will pretty much
do it nonstop. Have I given enough info? Any suggestions?
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since it has progressed over time, i'd say you have carbon buildup in the combustion chambers. this would raise the compression ratio, and thus cause the the air/fuel charge to ignite from the heat of combustion.
secondly, and im not totally sure on this, if your engine has a knock sensor, it could be faulty, and not telling the ECM to adjust the timing. maybe someone can shed more light on that possibility.
what octane gas are you using? the next time you fill up, you could try the highest octane you can get and add a bottle of octane booster.