exessive shifting

**PipeOrganDaniel** · 08-13-2015

I have a 2002 40th gtp
I have the past few days began to notice that I have exessive shifting it seems, My Aeroforce Gauge I have it set to show what gear its in. It shows the gears but it seems to shift ( sounds like it goes to another gear without actually showing it on the gauge when it does even though it shows when it has actuyally shifted if that makes sense , I have noticed my Cruise control quit also , could this be related, I lso disconnectred the battery cable for almost 2 hours , took the car for a drive and it still seems to be doing the same thing , , WHat could be causing this ?

**PipeOrganDaniel** · 08-13-2015

what controls the shifting times ?

**SgtMarshal** · 08-13-2015

pcm commands the shift. cruise control has its own control module, not related to the transmission at all. could be a bunch of stuff that cause's the cruise control to fail. not sure what would make your transmission act funny. hard shifts may not be a bad thing, but if it just started out of the blue with no tuning or changes from you, its probably not good. a fast shift is better because the clutches have less slip.

**PipeOrganDaniel** · 08-13-2015

this thing isnt doing hard shifting , just annoying what seems like going from one gear to another smoothly

**BrandonHall10** · 08-13-2015

You will notice a change in RPM's when the torque converter clutch (TCC) engages and disengages even if you're not changing gears or speed.

**PipeOrganDaniel** · 08-13-2015

I will change the pcm tomorrow , I have a spare

**PipeOrganDaniel** · 08-13-2015

I see a very slight change in rpms

**Scottydoggs** · 08-13-2015

after it shifts the rpm's will lower as the tc locks up then unlock as you hit the gas and get into it some.

you can test the lock up by holding the gas steady on the highway, the tap the brake with your left foot, the rpms should rise 2 to 400 rpm. thats the tc unlocking. then it will lock up again and drop the rpm's.

**BrandonHall10** · 08-13-2015

My guess it tcc, unless... Is all maintenance up to date? Clean MAF and all that....

**PipeOrganDaniel** · 08-13-2015

the tranny was rebuilt 14000 kilometers ago, I havent cleaned the maf sensor and stuff , I do have a couple codes come up on the aeroforce gauge. PO137 , and a P1133

**PipeOrganDaniel** · 08-13-2015

I did put a new air filter in last week

**PipeOrganDaniel** · 08-13-2015

as you describe how the TCC works, it almost sounds like this is what im having issues with, it it is , what do I do ??

**BrandonHall10** · 08-13-2015

Address your codes first.

**Bronco Boy** · 08-14-2015

FYI, Aeroforce has a "TCC Slip" reading.

**PipeOrganDaniel** · 08-14-2015

thats one of the things I have programmed to show, how do I read it and what do all the numbers on it mean
?

**J57ltr** · 08-15-2015

The TCC will also unlock when you release the gas pedal so if you are constantly moving from cruise to let off the pedal it will lock and unlock. The TCC slip will show about 20rpm or so when locked up and when you release the pedal it will jump like Scotty said. My car does the same thing if I'm cruising in traffic and need to let off to maintain distance between myself and the car in front of me.

Jeff

**SgtMarshal** · 08-16-2015

someone correct me if I'm wrong, my understanding of how the TCC works is pretty much just like a clutch on a manual transmission, you push the clutch in so the engine is disengaged from the transmission and you coast. the tcc on an automatic can engage and disengage much faster than the clutch on a manual, the other factor to consider is the actual locking, when the engine is making power and you are driving down the road, when you are in 4th gear the torque converter will lock and that is how you go into overdrive, I think it can also do it in 3rd gear.

**J57ltr** · 08-16-2015

Pretty much, but you still have a slight amount of slippage which I am told is normal and is to deal with NVH issues. Personally I don't understand why GM still uses a clutch. It would be so much more effective and efficient to lock the turbine shaft and the stator, but it is what it is. In one of the threads a couple of the guys mention tuning this out, by increasing the PW to 100% or something.

Jeff