1994 Explorer Pinging

Cleaning your MAF sensor and the other one on the throttle body may help a little. How many miles do you have on it? Are you hearding any rattling from inside the engine? When my '92 with about 265,000 miles on it started pinging it turned out that the timing chain was loose and had jumped two teeth. This seems to be very unusual for the 4.0 engine so I would rule out everything else before tearing off the timing cover.

I have the same symptoms on my '96. I believe the consensus is that its likely to be an intake manifold gasket leak. I haven't yet got round to undertaking this project so can't comment on whether this fixes it or not.

I've got about 180,000kms on it. I only hope mine last to 265,000 miles!

Cleaning the MAF sensor cured my '94 of this problem.

Vern wrote:

Same on my 92. I used to have to put premium in it in the hot summer months to stop it from pinging. Then I cleaned the MAF and have not had to use premium since.

There's the "remove the shorting bar" fix, which retards the spark 3 degrees:

"The bar was easy to find, it's in the passenger side of the engine compartment behind the diagnostic connection block. Look for a wire with a connector on the end taped to the large harnass leading into the block. The shorting bar is a small grey rectangular cube that plugs into the connector. I just grasped onto it and pulled."

There is also de-carbonizing. Carbon builds up in the head and on the intake valves, effectively increasing the compression ratio and making little glow plugs if the carbon gets red hot. Both of those things can cause pre-ignition or pinging. I read an old post by guru Jim Warman about adding a small amount of water to the intake of the engine as it idles, "steam cleaning" the carbon out. There are also kits of chemicals that do the same thing.

Search this newsgroup or the web for "pinging" "shorting bar" etc if you need more detail.

-Paul

Your engine is designed to run on 87 octane gas, so don't use premium. Regular use of premium tends to build up deposits and cause the pinging, according to posters in this newsgroup in the past.

Try some of the suggestions others have posted to get it to stop pinging. Maybe Jim Warman will have some suggestions too.

I put over 100k miles on my 94 using regular gas and it never pinged.

Could you tell me where exactly the MAF sensor is located? Thanks to everyone who responded to my question. I've searched for "pinging" on the rest of this group and have found a ton of information. Thanks again.

It's located on top of the air intake tube, held down with security torx screws (you'll need the security torx tool which is easily available). It's a snap to remove and replace. I clean mine with some electronic switch spray cleaner, be careful it's delicate, don't touch it, just spray till it looks clean.

I ended up in the intaken mainfold catagory Cleaning the MAF never fixed it. Factory gasket is hard plastic - doesn't seal well.

I was lucky. Mine (1992) developed some sort of problem (don't recall what) when it was only a year or so old and the warranty took care of the repair which included RR of the upper and lower intake manifold. I recall the service guy saying something like the factory gaskets were crap but the ones they put on to replace them should last the life of the vehicle.

I haven't put water in my carb since before there were catalytic converters. I was afraid the water might slam against the converter guts breaking it into small pieces. Is it safe, then? Thanks. To get rid of my pinging (166K now, but there since 100K) I use a tank full of 89 octane or a couple of gallons of premium every 4 or five fill-ups of regular.