I am the owner of a 2002 Excursion/4x4/ XLT,with an auto transmission. The truck is basically stock with an airfilter-Superchips tuner-and aftermarket muffler.

When I have the Tuner in the truck , it seems to shift alittle strangely. At 45mph, when it shifts into 4th I believe , the truck gets real , for a better word , touchy. By this , I mean , If at say 42mph , I stab the gas the truck will act like it is getting kicked from behind , then shift when i reach 45mph, or If I let off the gas , it will quicky decell , as if I am hitting the brakes. When i get stuck in a 40mph speed zone , the truck is real senstive to throttle, having it surge when my foot doesn't give the pedal constant pressure.

I did alittle test today , and the issue is still their when the Superchips tuner is off the truck , just does it more noticeably when the truck is "tuned".

Just wondering if this was normal , or if something is going on with my transmission, or toqure convertor...

Thanks for ther input.............

 

Joe- I'm no transmission expert, but I do have a theory.... my torque convertor locks at 36mph, and the shift into 4th is at 41. If I'm travelling at 42 and step on the throttle, the acceleration isn't nearly as great as if I were going 40, since I'd be in a higher gear at 42. The torque convertor has already locked up, so downshifting into 3rd takes a lot of throttle. Is it possible that what you're experiencing is merely the difference between being in 3rd and 4th? It might be that the shift into 4th is smooth enough that you might not realize that it has shifted. My remedy, BTW, is to lock out OD unless I'm going to be travelling at 45 or higher.

 

Quadzilla -

Thanks for the feedback, this has had me thinking for awhile.
I am going to the local NHRA event tomorrow , and will test out your Overdrive theory and see what happenes....

Thanks again ........