My 97 expy is pinging on acceleration, especially with a load on it(ac on) and when it is warm to hot outside. I run Amoco ultimate 93 octane in it. The plugs have been changed due to a faulty coil. It pinged before the plug change also. Any ideas for fixing this problem? It has 87000 miles on it.

 

Hey man welcome to the pinges club. I know it sux. My 98 4.6 PU pings, no matter what temp above 3,000rpm and when running down highway at 70 or so. Theres a list of things that need to be done, basically process of elimintion. NExt spring im gona get my truck out of the garage and tear into it trying to fix the problem. Possible causes:
1. MAF sensor behind intake is dirty
2. spark plugs/wires
3. O2 sensors
4. K*N oil clogging on MAF sensor
5. carbon buildup in intake due to high octane (91&93) a upper intake cleaning will take care of this delima

im sure theres more--do a searchon here for pinging and youll find tech articles on how to fix this and howmuch it costs. My advice,, quit paying for 93 octane. Its gona ping till u fix it, so get 87. You can try fuel injector cleaner, etc,but i cant guarantee its gona work. Its cheap so be my guest.

Do a search and find out what you need to have done
-Patrick

 

I agree with Patrick, especially number 5. With 87K miles, you might try a good fuel injector cleaning. Then, run some BG44K engine cleaner (~$20). A lot of dealers use this product. Suposedly the Bilstein engine flush (not sure of name) will clean all the carbon and junk in the engine. This is not a do it yorself.
Good luck and let us know what you find. Patrick is also right about using a higher grade than you need to not ping. Otherwise it will build up carbon.

Pet

 

Find a GOOD Tech and discuss reprogramming the PCM on the timing I/O 's.

Basically, you don't want the timing to retard (auto by PCM) when intake air temp goes above 140 deg's F ( ambient air temp over or around 100).