vtruck

2001 F-150 supercrew 4X4, with a 135k miles. It just developed a stutter between 45 and 60mph. Not easily detected in 1st and 2nd when accelerating normally, but present in or out of "tow / haul" in 3rd gear or Overdrive.

If I deliberately hold the truck in 2nd gear I can get the same reaction in this range of 45 to 60mph, although the stutter seems a little supressed under that kind of throttle.

If it were a fuel filter, I thinking I would have to use a certain amount of fuel before encountering the problem at all.

It feels like maybe a converter lock up issue or transmission related.

What do you think?

Thanks for any help.

Cecil

kaboom10

Sounds like it could be one of the coil on plug units. They can short out internally and give a weaker spark but not throw a code. A diagnostic machine will tell which one but if one is going you should just replace all of them. While you're at it change the spark plugs.

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02 F-150 FX4 w/Baer rotors,carbon kevlar pads,SS lines,remote coolers/filters. IAS shocks,LiveWire tuned by me.

vtruck

Thanks for the reply.

I drove it again today. deep in the the thottle, this problem jerking doesn't happen. The truck pulls good if you get on it hard. My wife reports it is worse when the engine is warm. At this stage I'm dealing with a light throttle nuisance.

The coil on plug coils are fairly expensive aren't they?

kaboom10

The way it was explained to me was thhat when the engine is warm the EGR is introducing exhaust into the intake stream. This causes the voltage requirement to increase around the speeds you're talking about. If you floor it the EGR can't put enuff into the inlet or maybe nothing at that accelerator position. The cost of a COP from a dealer is about $93. You can get a set off eBay for around $80 and I haven't heard any complaints. If you're not having any problems at high speeds the injectors should be working and they usually go forever.