Mess1328

Hello everyone, first post on the site although I've been a long time member. I've searched high and low on the forum and have found similar problems to what is going on with the truck but can't seem to pinpoint exactly what the problem is.

The truck is a 2006 4.6L. At higher RPMs the truck drives excellent. When coming to a stop the RPMs will surge, sometimes down to 200 and other times it will stall. At park the truck seems to idle on the rougher side, although at 500 RPMs, when put into drive it will move down to 400 RPMs. Along with these problems the gas mileage has been pretty bad, averaging 7mpg on the last fill up. When the problem started I visited O'Reilly's and pulled codes p0191, p0106, and p0109. With some searching through this site I gathered enough information to lead me to replacing the EGR valve. This helped the problem but not completely. After more sifting through forums I decided to replace the fuel filter along with the Fuel Pump Driver Module, which seems to be a common problem on many of these trucks. The old one was in poor condition but the new one didn't seem to do anything. After feeling like I've gotten nowhere I decided to bring it to the dealership. They replaced the MAF, which I was convinced was fine but they believed it was the problem. The dealership also did a fuel flush.

Well, after a few hundred dollars spent on parts and a $450 dealership bill, the problem is still there. At this point I am lost and do not want to go back to the dealership if I don't have to. The check engine light has not come on yet but the problem still exists and the truck will sometimes stall when coming to a stop.

At this point I am not really sure where to go and am open to any suggestions from you guys. This is a great forum and you guys have helped me fix many other problems in the past.

STSCDave

On my 4.2 V6 I was getting horrible mileage and it ended up being the fuel rail pressure sensor under the hood. The diaphragm was stuck and the computer couldn't tell what the fuel pressure was. It was running rich and blowing black smoke from exhaust when accelerating.

techrep

iTrader: (1)

have you removed and cleaned the throttle body yet ?

darrylgibbs

Is it throwing a code? My 4.6 mustang did something similar and ended up being a bad coil pack.

joe mcmillan

Plugs and COPS? How many miles and how old are they? What rand are they? Some aftermarket plugs and COPS do not perform. These are usually the first place to look. Sometimes these will cause the truck to display other codes and mislead the trouble shooting.
Standard air filter and intake? Some aftermarkets may be affecting the MAF and or throttle body.

Mess1328

The CEL came back on. Checked the codes and still have p0106, p0109, and a new one p0172. I took off the throttle body today and cleaned it pretty good. Put it back on and the truck did the same thing, very low RPMs while coming to a stop or slowing down.

All spark plugs were replaced in October of 2014 at the dealership along with the coil pack and I suspect they are fine. Both the air filter and intake are standard.

My next guess is to replace the O2 sensors, what do you guys think?

vintageman

Did you disconnect the battery when you took the throttle body off? If so, did you go through the battery relearn process? If not, then cleaning the throttle body may have fixed it but the computer is still setting up your driving parameters, meaning, relearning itself. Get to operating temps and go through the relearn process and see if it helps with your issues.
Good luck
Tom

06AriBei

I had the same issue before. I disconnected the battery plus reset my edge programmer to a stock 2 tune and completely forgot about the relearn. Attempted to drive to the grocery store and stalled out twice. I was panicking because I was clueless on what the problem could be. I did the whole relearn plus cleaned my throttle body. Good to go.

Mess1328

Well the dealer finally figured it out. It turned out to be a chafed PCM wire near the power steering column. Truck runs great now, after a month of problems it started to seem like I was just throwing parts at it and hoping to solve the problem.

Mod (Ret.)

Yikes. Sorry to hear of the loss to the wallet! There are times where the usual solutions offered to a symptom are not the solution. Tossing parts until its fixed is costly, and it would have been very doubtful that your problem of a chaffed wire would have been diagnosed over this site; something that probing signals was required to diagnose.