My truck runs great with "NO" ping at all when the temperature is above 45 degrees. If the temperature fall anywhere below 45 degrees, the engine will ping like crazy...

Anyone got any ideas as to why this would occur?

1998 4.6l V8, 55,000 miles. The truck has been doing this for about 2-3 yrs now.

Thanks for any suggestions.
Stan

 

Clean your MAF sensor. If it's dirty and unmeasured air is entering, you'll run lean. After cleaning it, reset your computer.

 

I have worked on this problem quite a bit over the last few years. My advise would be to start out by disconnecting the negative battery terminal and turning on your headlights for about 10 minutes to drain the juice and reset the computer. (This along with other things will reset your timing.) While the battery is disconnected, check your air filter, and clean your MAF sensor (both will take you less then 10 minutes.) Then reconnect the battery terminal, start the truck back up, and let it idle for 5 to 10 minutes for the computer to 'relearn' it's idle properties. Over the first couple hundred miles the computer will be relearning your driving habits, so you might try driving a little more aggresively over this period, especially at the points in your RPM range where you have expierenced pinging the most. If your problem persists at that point, it's time to go a step farther and clean out the throttle body and EGR system, replace your fuel filter, and then check the gap on your spark plugs, aswell as your DPFE sensor and IAC valve. At that point I would replace your oxygen sensors before having a customer chip burned to overcome the problem. If you will look in the passenger side door seal, you will see a white sticker with your computer 'program' on it it. If you have the FOU1 (like me) you will notice the problem the most as it is a common problem with the FOU1 program, and will most likely have to have a custom chip burned to overcome the problem completely. Generally speaking, the dealership is pretty useless in attempting to correct this problem. About the most they will usually do is replace the MAF sensor while your still under warranty.) I have been thru all of the above with the exception of having a chip burned, and still run 89 octange on a regular basis to keep from having any problems with predetonation. For whatever reason, my truck just likes a little more octane.

 

STX/98 and AjRagno, thanks for the comments...
and yes I do have the 'FOU1'. I have cleaned the MAF but have not tried the other things mentioned, I will do so. I know that I have not changed the fuel filter in about 30k miles.

Thanks for the input and yes I have to run 89 octane all the time myself.

 

I've done the same as STX/98. To end my pain and frustration, I simply use 89 octane once the temperature drops. The power will return and your mileage will go back up. Damn FOU1 computer!

 

I had a chip burned a couple of years ago to get rid of the pinging in my FOU1 4.6, I had it programmed to run on 87 octane.

Since then I have read that Ford has logic built into the ECU's to add 3 degrees of timing when temperatures drop below 50 degrees.

If that is true, that would explain why people experience more pinging in cooler weather. The FOU1 code must be fairly aggressive and the extra 3 degrees must push it over the edge.

 

The FOU1 engine code is NOTORIOUS for pinging. Almost all people who have it, and haven't done anything (i.e. chip, PCM reflash, etc) have continued to have pinging and detonation. Stop by your dealer to see if they'll reflash your PCM with a different code. That may fix your problem.

-Flea