I have an 05 F250 4x4 auto with 243k that has an intermittent problem. Overall, the truck runs great. Currently it is stock other than a 4in. cat back exhaust and an Airaid washable filter in the stock air box.

When I come off the throttle, the engine slips into 4 cylinder mode. It's a rough, out of balance idle. No smoke, no CELs, no odd sounds. It will maintain this condition until I tack it up over about 1500 rpms. I have been stuck in traffic and had it last for 12-15 minutes. I can tack it up and make it go away it go away as soon as it starts. I have also turned the engine off while it was in this mode, let it sit for 15-20 minutes and re-started, still in the 4-banger mode.

I recently had a shop do a deep scan with the Ford software and found nothing. The tech drove the truck for 20 minutes and couldn't duplicate the condition.

As you can tell from the odometer, I drive a lot. 100-200 miles per day is not uncommon. I might have the issue arise 3 times in one day, and then not happen for 3 more days. It is totally random. Loaded with a heavy trailer or empty, hot or cold temps. empty or full fuel tank, hot rodding or light footing it, nothing seems to be a common factor.

Any ideas? Thanks in advance.

 

Possible chaffed wire on the injector harness? I find it hard to believe the Ford dealership couldn't find it. Though some dealerships are better "equipped" (techs) than others.

 

Maybe clean MAF' sensor with caned air. I understand washable filters might compromise them?

 

does your truck at parked idiol entermittent stumble or even stall, thats what my 04 350 6.0 does too.how about cool out side temps runs good or no. sorry for the high jack, trying to solve the same issue too.

 

No, the engine never stops. It feels like it is going to stall but keeps running. Outside temperature doesn't seem to make any difference. I have a Scanguage II and nothing shows up during the condition. If it was wire chaff, wouldn't the truck quit and not re-start?

 

hey bone 3 , one would think a chaf wirewould keep the truck from starting but a short. two wires grounding out on each other or a bolt is common in these trucks look thru the tec folders on this also inside the rocker cover thats where I think my trouble is These guys in FTE are pretty good , also connections ficm etc thats what I have been reading on Fte check ur voltage .Good luck and keep use posted theres always a different case in all trucks.

 

I would recomend watching the ICP and IPR values