Using advice from this forum, I have done the following to try to eliminate pinging on '98 F150 with 4.6L but it still pings under load when warmed-up:

Cleaned EGR ports at throttle body (they were plugged).

Replaced fuel filter (vehicle has 90,000 miles so it was time anyway).

Applied full vacuum to EGR valve to check operation - started idling rough and then smoothed out some probably due to IAC compensating. So I will assume EGR valve is opening with full vacuum applied.

Drove vehicle with EGR valve forced open with full vacuum - idle same as described above and pinging still present at load.

Checked vacuum at idle = 19"Hg and steady.
Checked vacuum at 2-3,000 rpm = 24"

Added fuel injector cleaner to gas.

Re-routed #7 and #8 plug wires.


Is it possible that the DPFE is bad? How to check?

or

Could there be additional EGR pluggage in the EGR valve that is limiting EGR flow?

So far no CEL codes since I bought the truck new 6 years ago.

This is a good truck with a minor but potentially damaging problem. All help is appreciated.

Mike

 

what brand plugs are you running, what plug gap?

Also clean the mass air sensor with some contact cleaner.

JH

 

A contaminated MAF, causing the engine to run lean, is probably the most common cause of pinging. The simple way to check it out, is to disconnect the MAF sensor, which will force the PCM to fall back to default values programmed into the computer. If this clears up the pinging problem, then you have found the source of your problem.

 

Thanks for the responses.

I cleaned the MAF with brake cleaner about a week ago. Maybe it is not fully clean. I will try disconnecting it temporarily as you suggested.

The plugs are original so the gap is unknown.

Today the weather is colder and rainy. No pinging.

Mike

 

mike, no pinging with colder and wetter weather suggests denser air coming into your throttle body which as already suggested may indicate dirty MAF. The maf senses the volume and the mass of the air coming into the throttle body. When you clean the MAF again, leave battery disconnected for 20 minutes or so. Upon restart your engine computer will sense the cleaned MAF.

assume you have a clean air filter.

i usually soak my maf in a bottle cap full of brake kleen for about 15 minutes (versus a spray treatment). I dont claim to know the exact reason but no pinging at all from my 97 4.6 with 174,000 miles even at wide open throttle. Might just be the particular engine. also, i run only a name brand regular gasoline.

 

go to a awfs-22c spark plug and call it a day. gap them at factory 0.054.

The 22c is one heatrange colder than stock, and is copper for better conductivity.

It will last about 30k and solves most pinging problems.

JH

 

There is a thread in the 97 - 2003 section that shows you how to clean the MAF. I had a similar problem and followed the directions (shows you how to remove, disassemble and clean the sensor) then reset the computer. Cured my problem. Good luck.

 

I had the same problem and just fixed my 5.4. It was pinging terribly under load and I was getting a code PO140 Insufficient EGR flow. I took the throttle body off and cleaned the ports (they weren't very dirty) but it didn't help. I tested the EGR valve with the vaccum trick and it was ok. I replaced the DPFE sensor (at autozone they didn't know what that was....it's also called a EGR valve sensor, I think). That did the trick. When I took the old sensor off, it had a lot of build-up where the two hoses connect to it so I might could have just cleaned the old one out, but since I had the part I replaced it. Runs great now.

 

I have had to use 89 octane since it was new. '98 4.6

 

I have a '98 Expy with the 5.4L and was also experiencing detonation under load. It wasn't severe, but it was annoying. It was worse when the AC was on, and also very noticeable after the 2-3 shift. I tried all the usual tricks, cleaned MAF, replaced EGR valve, replaced DPFE sensor, none of these worked. Also, the problem lessened, but did not go away, when I burned higher octane gas.

Finally, I called the Service Dept. at a local dealer and talked to a very knowledgeable writer. I explained to him what I had done and how much time and money I had spent troubleshooting this problem. He told me to bring it in and they would check to see if I was showing any codes (I wasn't) and try to re-program the engine Program Control Module per TSB 001203A. It would cost me $40. BINGO!! No more ping, and I even tried to load it heavily. I turned on the AC, let the tranny shift into OD, let the rpm's drop to about 1500, then floored the accelerator just enough to make sure the tranny didn't kick down. No ping, everyone happy.

I know this applies to the 5.4L, maybe someone can check and see if this TSB also applies to the 4.6L. Heck, maybe someone can link us to the TSB.

 

Iwong,
I'm having the same exact problem as you described.
How long did it take for the programming? I'm thinking of calling my local dealer to see if they can do that b/c my '98 5.4 expy is driving me nuts with the pings, b/c other than that it drives great!
Thanks for the info!
Phil

 

My 99 5.4 has the same problem. I did all the things Iwong did but it still pings under load. I was getting a CEL which was fixed with a new DPFE sensor. I called a local dealer yesterday and they want $80 to reprogram the program control module. They said it might be cheaper if there is a TSB on it. I tried to find some information on the TSB Iwong listed, but I couldn't find anything.

 

I don't know how long it actually takes for them to re-program the PCM, certainly less than 2.5 hours. I dropped it off at luchtime, ~noon, and I picked it up at 2:30PM. This is what was written up on my service order:

Perform quick EEC test, passed, program PCM to latest calibration level per TSB 001203A

I would guess that since some sort of EPROM is involved, the actual programming time would be in seconds, just my guess.

I drove my normal route this AM in to work, and where it usually detonated prematurely before, did not happen today.

 

Thanks! I'm interested in seeing what my local dealer will say when I ask them about this.

 

thanx guys. my 97 4.6 with 170k pings only when the engines cold. when it warms up it runs like a champ. now i have stuff to try to get rid of that annoying crap.