RJMcEachern

hello!

I have an 87 GTA 5.7L Auto, running a 165 MAF ECM. When driving around town under what I would consider is normal stop light to stop light driving when shifting from 1st to 2nd the car shifts at 1800 (+/- 200) and chirps the tires regularly, car has alot of power in WOT, but trying to resolve normal daily driving transmission shift rpm, anybody know which parameter to alter in order to change trans shift rpm's?
Is this even possible? I am thinking the trans has a shift kit in it as it shifts very hard from 1-2 and 2-3 when in 4 it is around 1200 rpm @ 40 MPH. Even when the trans downshifts as you come to a stop it is a noticeable hard shift.

I am wanting to know which table, scalar, etc to modify to alter the shift points of the tranny relative to RPM.

RJMcEachern

Six_Shooter

iTrader: (2)

Your trans is not ECM controlled, so there is no in PROM change to make to change the behavior you're seeing.

mmadden55

Adjust your trans cable, assuming you don't have constant pressure trans.

RJMcEachern

awesome, thanks, i'll try that! it is the stock trans, however I do not know if PO somewhere along the way put in a shift kit. I have had other cars that had shift kits and this shifts hard like those other cars did.

RJMcEachern

windowrattler

iTrader: (3)

The governor in the trans controls the shift points. It is basically a springs and weight set up similar to advance in a distributor.

RJMcEachern

Thanks! I will look for a softer spring to allow shift points in cruise mode at higher rpm's? or is it the opposite? firmer spring for higher rpm shift points?

It seems to work great at WOT in that the trans doesn't shift from 1-2 until about 2800rpm, 2-3 4800 rpm, and 3-4 until 5200 rpm, this has some variance of course.

RJMcEachern

I H8 WWD

iTrader: (5)

Even with a shift kit, during simple driving, the car should act as normal. The trans shouldn't jerk hard when slowly creeping to the next gear. Mine shifts smoothly without jerk, once warmed up (this helps a lot). When I go WOT that's when it shifts hard, and downshifts hard when decelerating quickly. Just as a shift kit should do.

Check your fluids with the car at operating temperature and on flat ground. Maybe change the fluids if dirty. Adjust your TV cable and check your throttle cable for slack.

I'm looking into a temperature guage for my trans fluid. I'd like to see at what temperature it sees fit to act correctly. As when it is cold (below 130* or so) it does shift a bit harder.

So when you launch it from a dig at WOT (pedal slammed to the floor), the car shifts into 2nd at 2800rpm? I must be reading or interpreting this wrong. That can't be right if you are truly WOT and everything is adjusted/installed correctly.

RJMcEachern

those are verified as of this morning, it appears it is running great, BLM's always at either 128 or 126, no lower than 124, AFR WEGOII shows 14.6 while cruising, WOT shows 12.4 AFR, motor pulls hard and strong all the way to 4500 or so then starts to drop off, I have not had it on a dyno yet or on a 1/4 track, just some local small auto crosses.

I did do some WOT throttle runs yesterday with plug pulls immediately after the runs and the plugs look great, pulled one from each side and different plugs each time I did a plug cut, all 6 (didn't pull last two), looked slightly brownish, with just a hint of black, figure this is from WOT rich (12.4 AFR).

Just need to address the Auto trans and its shift patterns...

RJMcEachern