kendogg

iTrader: (2)

Hey guys! I bought a truck last night ('97 Cheyenne 2500, 350 Vortec 4l80e) that has a goofy shifting problem. It seems to shift into Drive or Reverse just fine, no lag, no bang, etc. However, it seems to not want to shift without a little lift of the throttle, especially at WOT. Any ideas where to look? Doesn't seem to slip, make any weird noises, etc. Could it simply be a fluid issue, or is this electrical or mechanical inside the trans?

Jake's Performance

iTrader: (2)

Put it on a scanner and look at your VSS and TPS data or any codes.

kendogg

iTrader: (2)

No codes, but I'll look at TPS and VSS data. TPS is a simple check, but what am I looking for with regard to VSS data? Am I simply looking to make sure a signal is present and accurate?

Jake's Performance

iTrader: (2)

Yes,
Watch the TPS sweep carefully, often they have a dead spot in the area of cruise.

Be sure the VSS looks correct.

kendogg

iTrader: (2)

OK, i'll check it out. Thanks!!!

kendogg

iTrader: (2)

I know this is an ncient thread, but I just realized I never updated it. Dropping the pan & changing the trans filter, along with new fluid helped a LOT. A few more drain-fill's just dumping the drain plug really helped a ton. Just used Maxlife ATF. Works great now, have put 10k miles on it since, mostly work/towing or highway driving.