Vehicle in question: 2000 Expedition 4x4, RCD lift kit w/ 35" BFG's. Superchips flip chip.

Conditions: Summer, and warm 85-90+. From a dead stop. Filled w/ 4 passengers + gear.

Symptoms: After driving 75+ miles on the highway, we pull into the city. From a dead stop the truck accelerates EXTREMELY slow, staying in gears for way too long...almost not wanting to shift at all. Also, the fan (radiator) is spinning pretty loud and it's pace matches the accelarator speed.

These symptoms happen after driving a while in hot weather. I've never experienced them in the winter.


Any ideas?

 

Yep, normal.

I got a little relief after adding the Airaid air intake. Best I can tell, the more freely breathing Airaid just lets it suck a lot more volume letting it get a little bit more real air.

It drives me nuts, but I've had it to a point (in 100+ temps in heavy traffic) where I thought I'd have to bury the peddle through the floor to get the thing to just move. Once driving for a while, and I stop in 90+ heat in traffic, it'll do it but not quite as bad and once you get going and get some air flowing, it gets better....

If you find a cure, let us ALL know!

 

Does it do it in both modes of your flip chip. Also, this is a real long shot, but if your engine is overheating it selectively shuts down cylinders. Good luck.

Pete

 

Check TSB 02-12-3. This pertains to the lack of power in the 5.4 at high ambient temperatures. The dealer can reflash your PCM to compensate for it. Of course, with the cooler weather, the dealer will probably not be able to recreate the problem and will not want to do anything.