Carson,
Check the thread 74067 located in the engine section (this web site) under Engine Knocking, last post was 4/27/02. It should describe the DPFE & associated info. It helped me.

 

Here's the info. in that post:

"The history of my problem is that my truck would ping either under load or whenever I went over 1/2 throttle. I cleaned the EGR (Exhaust Gas Recirculation) valve and passageways, installed new plugs and wires and ran several bottles of cleaner through the system without any help. I also have ECU code FOU1.
I hooked up my voltmeter to the EVR solenoid to watch when the ECU was calling for the EGR valve to open. The EGR valve is designed to induce significantly cooler 1200° F exhaust gas into the combustion chamber that is at least 2500° F. This allows the engine to run on lower octane gasoline with less chance of spark knock.
Sure enough, whenever I put the engine under load (even going up a moderate hill) or went over 1/2 throttle, the voltage signal to the EVR would shutdown and therefore the vacuum to the EGR would be cut off.
So I cleaned the DPFE sensor and hooked everything back up and went for several test-drives. Now the EVR valve continues to receive a voltage signal except at WOT and idle and the pinging is gone!
If your engine is still pinging after many different attempts to fix the problem, you might want to give this a try, it didn't take much time and didn't cost anything.

Since the location of the DPFE sensor may be different from your '97 to my '98, probably the easiest way to find it is to locate the tube that runs from the exhaust manifold to the EGR valve. That tube has two T-fittings that have rubber hoses connected to them. The other end of those rubber hoses are connected to the DPFE sensor (a little bigger than a deck of cards and it has a 3 wire harness connnected to it).

I was desperate and the only thing I had handy was WD-40. I removed the sensor, turned it upside down and sprayed WD-40 into the two tubes/orifices that the hoses were connected to. I let it sit for a while and then emptied the WD-40 out and let it dry before re-installing."

Hope this information might help someone else like it did me.

 

pinging can be caused by a contaminated MAF sensor as well. this is usually indicated by a BARO pid reading of 130-140 Hz (provided you aren't waaay up in the mountains that is) The PCM undermeters the air flow, thinks the engine load is a lot lower than it actually is, and applies way too much spark advance for the given load, and all of a sudden you're pinging.


The truth is out there...........

 

I had the dealer replace EGR and DPFE and that helped for about a day. The engine still pings under almost no load but it always seems to when it is in 3rd. or 4th. gear any load and it's definitely worse. It started ping in all gears but I checked the oil and sure enough it was a quart low, after I added oil it went back to pinging in 3rd and 4th. The dealer said they have no clue and I'm at my wits end. I only have 55k on it and the dealer said everything else is OK. If anyone can help it would be really great.
98S/C
4.6

 

Perhaps there's a small vacuum leak? Did you clean the little sensor in the MAF with a Q-tip and windex? (be gentle)

Did they clean the EGR passages as well and not just replace the DPFE & EGR valve? I think the EGR passages in the throttle body can get clogged too. Do a search for that on here.

Maybe the IAC (or AIC - brain fails me) could also be faulty.

 

Carson ...Did the dealer put in 5W20. I ran 5W20 through winter til mid April in Wisconsin. I noticed a bit more pinging, especially when towing, and lost about 1.5 qts on one 800 mile weekend trip. I do not like the 5w20 in my 99 4.6L (45k miles) unless it is very cold. There is noticeably less pinging on the highway and towing with 5W30.

2 thousand mile ago I upgraded to LT265/75R16 tires. Had the dealer reprogram the computer and that did improve power output. With my 3.55 rear end, there is increased pinging due to the greater engine load. I'm operating even lower in the power band and the transmission is shifting more too. I just try and take it easy and not drive like a sportz car. The problem is even worse diring the 90 plus heat of summer. Now if I tow anything, I do it with overdrive off.

Don't get me wrong, I'm not complaining. I'ld buy another F150 tomorrow, buy I'ld opt for a 5.4L and a 3.73 rear end (or more with bigger tires). JMHO

 

just for grins, you might want to check and make sure that your EGR pressure sensor and the electronic valve switch that associated with it are running okay...

 

I still cant get any power from my 4.6. Here is a summary
engine ping with 87 octane
no engine ping with anything higher
worse power output in 90 degree weather no matter what gas
no trouble codes(so im assumng that the egr anf maf sensors are fine)
265 75 16 tires
idles fine( purrs like a kitten no hesitations)

There is such a lack of power that i cant go 120km per hour on a 5%grade in overdrive without downshifting. It feels like im driving in sand (tire pressure is fine). I do not want to bring this to the dealership as they will charge me through the %$# and probably not fix the issue.
Im redoing the plugs this weekend but i dont think it will help as much as this truck needs.
I read in another post about reprogramming the computer with the "offroad package". Do you think this will put me in the powerband?


*Also i never paid any attention to see if there is a drain plug for the tranny fluid or do i have to pull the pan to change the fluid?
99 4.6 sc 3.55ls

thanks in advance for the ideas!!!
carson

 

I did the plugs on the weekend. I put in autolite platinums. I also changed the fuel filter.
Well the results are great! Smooth acceleration, better shifting no lagging throttle and so far the ping hasnt returned.
I can now spin the tires a bit on dry pavement.
Anyhow quite a difference. Im thinking more than anything it was the fuel filter ??
Anyhow the whole thing including an oilchange cost me about $75 and i didnt even scrape a knuckle. It took me about 3 1/2 hours including an hour to drive accross town for a tool to remove the fuel filter. I bought the plastic one and it worked fine ($5)
Thanks to you guys on this site I was able to get the filter off without recking the hoses( lost temper and was going to cut it off!) never did though... instead i searched the site and voila. Thanks for the help.
Hope these results help someone along the line.