Guys, I'm sure it's been talked about, and I've searched for a while...
My 87 (70,000 mi) pings upon acceleration, even on 91 octane, and idles up and down, occasionally stalling. This car was maint-
ained by GM very well......
Where to start? I've already changed the fuel filter and air filters....
Any help will be greatly appreciated.

 

Egr valve? Use premium gas? Checked knock sensor? Cleaned IAC?

 

I do use premium gas all the time, but I'll check out the other parts-
Thanks for the response!

 

Your timing is advanced too far.

 

Nope, timing was my first thought....it's dead on at 6 degrees BTC
at idle.....

 

Try 2 or 4 degrees BTDC to see if it makes a difference. Sometimes some engines will run better when the timing is slightly off of the manufacturer's specified value.

 

Have a look at your cap and rotor. My 87TPI seems to eat those components within a year. Will ping under heavy acceleration till I put on a new cap and rotor. Then it's ok for another year.

 

Simple things that make the car run lean.... vacuum leaks.... check your O2 sensor as well.

Also, if you havent given it a tune-up recently then you might want to give it the whole once-through.

but... Vacuum leak is my vote.

 

I agree vacuum leak as well letting unmetered air into the car causing lean condition. lean causes combustion temps to be high which will lead to detonation


your car should run justfine on regular gas and really should only use premium if you have higher compression or advanced timing otherwise it does nothing for your car


another thing you might want to check though is wear in the distributor. take the cap and rotor off again and wiggle it there should be no play. it might rotate which on my car is normal but don't know about yours but it shouldn't fee sloppy and move side to side


what this will cause is your timing to bounce around which might cause some detonation issues