I have a 1994 Explorer with 150 000 miles on it. Everything runs good except for the engine ping. Here is what i have done so far

1.flush carbon
2.change and gap plugs and tuned up
3.change EGR valve
4.clean MAF
5.Disconect the batery to try to reprogram computer
6.Checked Baro reading on MAF
7.Re torq lower intake bolts
8.tried almost all gas and oil treatments made

Right now I am running it without the shorting block and it still pings occsionally. It seems to do it most when holding speed steady going up a hill if you put it to the floor it goes away until you reach the top. Please help i really dont enjoy running it without the shorting block it hurts gas mileage and it has no power.

 

Have you checked the timing? Has the timing chain ever been change? 150,000 miles is a good run if it has not been change. You should be on your third timing chain or do for one. Does it do it with all three grades of gas?

 

Did you just spray the MAF or did you scrub it? When I first had this problem I sprayed it and there was still a ping. When I used carb cleaner and an old toothbrush to GENTLY scrub the filaments, the pinging went away.

 

Also be sure to check for other vacuum leaks. Including a ruptured AT vacuum modulator diaphragm (will have ATF in hose).
Sometimes, torquing the lower intake manifold bolts isn't enough. The gasket is so beat up it sometimes requires replacement.

 

I have tried all 3 grades of gas it pings less with 93 but it is still there. I also tried scrubing the MAF with a tooth brush a few times. I did not think of the timing chain or the AT vacuum modulator diaphragm. Thanks for the tips.

PS
Anyone hear anything about testing the vacuum on the EGR system.

 

Funny, Im having the same problem with the same model and year but have not yet done anything till saturday, im going to try everything you mention, I hope I have better luck and at the same time im afraid, now that I read your post is not going to work, but lets be positive right..............

our moderator should put a sticky on this topic, since like myself and others have been posting about the same pinging problem.

 

A buddy of mine who works for ford said to look for cracks on the MAF and around the plug. He said the plug on the MAF will give the same problems too.

 

Heres an XLNT link for anyone having a pinging problem. www.glue.umd.edu/~singletn/web/pages/ping.html
Gotta love the very simple 5 minute water injection trick that one guy came up with to remove carbon that causes pinging. How to clean the MAF is also covered.