94 Explorer XLT question

Hey everybody-
My Explorer pings like crazy if I run regular fuel in it. If I run Premium it silences it up quite a bit. I recently tuned it up (new plugs, wires, air filter) and it still sounds like a diesel if your going up a hill or putting some stress on the engine. I know he 94's aren't that powerful but the thing shouldn't ping like crazy when under a little harder acceleration. Could it possibly need a fuel filter, as I have never changed it in 40,000 miles. I'm figuring it it may be a sensor or something as it does have almost 130,000 miles. This thing is like a new car in and out and I have really tried to keep it in excellent condition, but this is one thing that drives me nuts more than ever, because of the gas prices. Do Explorers have knock sensors? I know my 96 Blazer does and I'm figuring the Explorer does to. If it does have one, where is it? Any help as to what could be making this thing ping like crazy, I would appreciate it.

do you think it's your lifters making the sound?

m f

It could be but it goes away if I put premium fuel in it and I replaced the rocker assemblies on each side and new pushrods and mounting bolts and everything was tightened to factory specs. It pinged even before that work was done. When I start it up cold in the morning it does have a light lifter tap until it warms up. It has pinged on regular gas since I got it 3 years ago and I have always run premium in it but am tired of paying the gas prices. I know first gen explorers are known for pinging like crazy and need to know if there are knock sensors or something like that or if a clogged fuel filter could be causing the problem. Thanks

my '94 was doing the exact same, but was also loosing trany fluid, so I changed the modulator valve on the trany, and problem was solved

There is a knock sensor. Or if your running to high of cylinder temps like EGR not working or running lean.

Check your transmission fluid level too.:)

Will a bad EGR cause pinging? Where is the knock sensor located??
Thanks

Actually, I guess that there is no knock sensor... I did run a cross a bulletin about Mass Air Flow sensor problems that lead to pinging/detonation. Which causes a lean condition but it needs to be verified with a scan tool or you could just be throwing parts at it. EGR should throw a trouble code if there were problems with that system. There is quite a few things that cause pinging with the worst of having excessive carbon build up on the pistons so the carbon doesn't cool and burns the fuel prematurely<That one is really out there though. It may be a difficult task to figure out. Sorry can't come up with easy answer.
Good luck.

I guess I should have been more descriptive, seeing how most mechanics today are parts changers. The modulator valve was leaking, causing fluid to be sucked into the vacume system and being mixed with the gas, which aparently lowered the octane,and then caused very radical pinging on regular pump gas. High octane was all I could burn until I fixed the prob.

Talk about parts changers... I had a guy working for me that could teardown and build 4L60Es in 3 to 4 hours (and they worked well when finished) but he didn't even know how to diagnose a transmission.

Not in our little shop

I had trouble with a nasty ping with my '94 Explorer. I explored all the other stuff as mentioned down the thread with no luck. I tow a snowmobile trailer with mine and it is plenty loaded down. The ping gets worse under load.

I was fortunate to have known an engineer up at Ford who worked with people who calibrated EEC and was able to remember what was done 10 years ago. Keep in mind, new parts don't usually have calibration problems. So I was pretty lucky we were able to figure it out.

Since there is no knock sensor, the gen 1 Explorer relied heavily on the mass air flow sensor to be properly calibrated. It appears it can loose it's calibration over time. The end result is it can trick the engine controller into leaning out the fuel mixture.

I replaced the MAF and my troubles went away. It's been several years now since I fixed it.

Bring money the Mass Air Flow sensor is not cheep. Plus bring your old one for a core change.

Good luck.

Thanks for the tips everybody. On www.ford-trucks.com I found a procedure on how to go about cleaning the mass air flow sensor. When I get around to it I will let you all know how it turned out. Thanks