First of all, thanks in advance for any thoughts/opinions on my truck's problem. I'll try to be as detailed as possible, so you know everything up front. **Edit**sorry I forgot to mention that it has the 5.4, and that the following conditions also occured when I took the O/D off.

I was cruising down the highway on my way back from Dallas today at about 74 mph and was about 1.5 hours into a 2.5 hour drive. Suddenly, the truck seems to "starve" for fuel (kind of like a lugging down). I let off the gas and it seemed to return to normal. I pulled into a nearby gas station and popped the hood to look for anything abnormal (found nothing). Checked the tranny fluid and it was within the "hot" range on the stick. Tried revving the engine, and no hesitation whatsoever. I then went to get back on the highway and everything was fine until I hit about 40ish and it started lugging again. I might add that this was with a pretty firm acceleration, but not kicking down into "passing gear".

Also, when it "lugs", the tach swings up and down with the lugging. I did notice that if I take it easy (grandma easy), I can get up to 70 without the cutting out/lugging. However, give it a little pedal at that speed and it lugs again.

I'm taking it to the mechanic in the morning, but was wondering what I could expect them to tell me.

Thanks again for those who take the time to read and respond to this, as I would really appreciate it.

 

I think I may be having the same issue with my truck.

https://www.f150online.com/forums/sh...d.php?t=307538

That's the topic I started, what else does yours do? Anything? Any check engine light?

 

No check engine light. It just seems to "surge" under moderate acceleration. Surge/fall back/surge/fall back...until I let off the gas and then gently ease the throttle back up.

 

Very puzzling. When I went to take it to my mechanic this morning (20+miles), I could not get it to do the surge thing. It took off like it always had. I decided to wait to see if it did it again before going to the mechanic. Could it have been bad gas ? (Although I filled up that morning and ran the one tank the whole way).

Weird...

 

engine bogging under heavy acceleration is often a dirty MAF sensor, try cleaning it see what happens.

 

My 2003 scab 4.6 does the same thing. I searched some of the symptoms and have narrowed it down to the EGR Valve and the DPFE sensor. one or both of those. I am starting with the DPFE sensor which I am told that ford dealer is the only place that sells them. Something to do with the exhaust gases and the sensor not reading the EGR correctly. Do a search on this and you will find some info describing the same symptoms.

 

You can buy aftermarket DPFE's, but they are junk.

 

I just got done spraying the MAF Cleaner onto the MAF. I'm going to let it dry for about 15 minutes and then see how it goes. I will let ya know how it goes, since we seem to be having the same issue.

Good luck with yours


UPDATE: Cleaning the MAF didn't solve my problem. May check it on yours, as it did seem to help... slightly.

 

Thanks for the replies, guys. I will try cleaning the MAF to see what happens. At 48K miles and dirt road driving fairly regularly, it probably needs it anyway. I tried to make the symtom occur again this evening on the way home from work, but the truck ran normal once again.

I trudge on...

 

Have you tried taking it up a hill and bringing it into passing gear and see what that does? That's where mine usually shows problems.


If it's anything like what I've got happening, yours probably will to. If not, try the same after a 10 minute drive or so.