frank b Posted July 24, 2008 Report Share Posted July 24, 2008 97 lumina 3.1 auto with OD. Sometimes, and just sometimes the tranny will not downshift into 1st unless you come to a complete stop. I replaced the vacuum modulator valve, which made a world of imporvement acrossed the board, firmer shifts, more positive engagement, etc. It hasn't been all that long ago that I changed the fluid and filter. The fluid was 1 pint low, so I topped it off. Yesterday it did it again, unless you come to a complete stop, it will not downshift into 1st unless you floor the throttle. Everything else is ok, it shift other gears, goes into OD, and the torque converter engage fine. Is this a bad solenoid? Does the tranny need to be removed to replace the solenoids? Quote Link to comment Share on other sites More sharing options...
Crazy K Posted July 24, 2008 Report Share Posted July 24, 2008 vacuum leak? the solenoid could be responsible.... Quote Link to comment Share on other sites More sharing options...
BXX Posted July 24, 2008 Report Share Posted July 24, 2008 Its suppose to do that, especially if it is hot... The PCM will not allow it to shift down to first with partial throttle until 8mph... If you were to enter WOT, 94-100% TPS signal, then it will downshift at 30mph into first.. And yes, this is all correct. Your PCM can be tuned. If you are interested in having your shift tables modified, PM me.. I have been through a lot with tuning these shift tables. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted July 24, 2008 Report Share Posted July 24, 2008 Does that mean the tranny is overheating? Quote Link to comment Share on other sites More sharing options...
89SupremeCutty Posted July 25, 2008 Report Share Posted July 25, 2008 Its suppose to do that, especially if it is hot... The PCM will not allow it to shift down to first with partial throttle until 8mph... If you were to enter WOT, 94-100% TPS signal, then it will downshift at 30mph into first.. And yes, this is all correct. Your PCM can be tuned. If you are interested in having your shift tables modified, PM me.. I have been through a lot with tuning these shift tables. correct. i have a 98 lumi with the same drivetrain and it's dosn't downshift below 8mph unless you floor it. the area im in when i leave work i do rolling stops and there are a couple streets i turn onto that i i do that and it seems like its starting out in second but it's not. Does that mean the tranny is overheating? no. cause the car is still moving. at least that's the logic im thinking of. Quote Link to comment Share on other sites More sharing options...
frank b Posted July 26, 2008 Author Report Share Posted July 26, 2008 Thanks for the replies. The car has never done this before. So something changed?? And it isn't every time you slow down then speed up, just sometimes. I"ll have to pay better attention to it to see if it only does this after the tranny has ben hot for a while. I recently installed a new radiator, which has made an improvement in the engine temps, so I would like to think that the tranny temps are lower as well since the rad has a tranny cooler in it. Maybe I'll add an external tranny cooler. Quote Link to comment Share on other sites More sharing options...
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