Automatic Transmission - 4l80e question, late/no shift until throttle lift



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kendogg
05-01-2012, 02:40 PM
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
05-02-2012, 02:15 AM
Put it on a scanner and look at your VSS and TPS data or any codes.
kendogg
05-02-2012, 09:41 AM
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
05-02-2012, 11:36 AM
Yes,
Watch the TPS sweep carefully, often they have a dead spot in the area of cruise.

Be sure the VSS looks correct.
kendogg
05-02-2012, 12:28 PM
Yes,
Watch the TPS sweep carefully, often they have a dead spot in the area of cruise.

Be sure the VSS looks correct.



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