to shift in and out of overdrive erratically. I've talked to a lot of people with auto trannies and they all told me that was normal. Even if it is normal, I don't like it. Is there any way to fix this problem or stop it? (Without driving in "D" or putting in a manual tranny) If not, I guess I'll just live with it. One last thing, how hard is a tranny supposed to shift?

 

I dunno the exact technicals, but this is the best explanation i could come up with... When rollin at like, 30, the car thinks itll need third, so it stays there. Then you tap the gas, it finds its more power than it needs, and jumps to OD. Mine does it all the time. Ive had it checked and its in perky perfect shape. Mine shift fairly hard... Actually, i have to be careful with it, in rain, itll break em loose under normal driving loads... (on dry, i gotta be speedin fer that). I know of one way to fix it, but it sucks. I used to have a pickup with a TH-350 tranny. The previous owner had disconnected the downshifter cable, or something... So it would only downshift when i came real close to a stop... I guess it was set at certian speeds... but like, driving around town, up hills and ****, it would stay in third all the time, it didnt have fourth.

Lemme tell ya, i know the constant bounce between third and fourth sucks, but havin it so it wont kick down REALLY sucks. I HATED it. i found out what he had done when i went to have it UNDONE. LOL. Trust me, it seems like it would be cool, but when yer drivin, and some dork in a 3.8L stang rolls by ya, you cant downshift withough yankin the shift itself, which cant be good for it, hhehe. Id just do what i do. Look out the window at the pretty girls, turn the music up a little louder, and forget about it. You look bad as hell in a third gen anyway.

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1988 Formula, 305TPI, 700r4(for now), headers, stage 2 PROM, modded MAF, cat back, no catalytics, cowl hood, centerline champ 500 rims, KOBEL predator ground effects kit, Trans AM tailights, dash pouch, 92 shift console w/indicator, white face gauges, accented red trim, 12 speaker stereo, 4 amps, tint, T tops... icq 44373460 AIM:admrlam
see it at www.geocities.com/admrlam/bird.html

 

It's not switching between third and fourth. What it's actually doing is locking and unlocking the torque converter. If you are crusing at 35-40mph, the TC will lock and unlock, because you are at the threshold of TC lockup. There are a few ways around this. Since the torque converter clutch is computer controlled, you can have a custom chip burned, and have them raise the TC lockup speed. That will eliminate the constant locking/unlocking. Or, you could buy a lockup harness - I don't recall what company makes one, but they are available in Jegs, and are designed to eliminate this problem.

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91 Trans Am WS6
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter

supposed 'peanut cammed' car (yeah, right)

MoreMoodThatMod

 

The trasmission TC clutch is fully controlled by the PROM. There are multiple tables and constants that control when the TC is suppose to lock up (and unlock). I burn my own PROMs so I set the TC lockup point to a higher Mile/hr.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Well, it still does it no matter what speed I am going. I guess I will just live with it. Gotta concentrate on a bigger problem now anyway. Thanks for your input guys. l8r

 

TRAXION... im a bit wonderous, im new at this, been playin wit my car for a year, mostly cosmetics, and im just gettin to the technical aspects... I always just assumed it was goin 3 to 4, 3 to 4... What does the torque converter locking up actual do? And unlcoking... And what is the significance of the speed it is set at? Also, you said you burn PROMS? Whatr does that cost exactly? hehehe

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1988 Formula, 305TPI, 700r4(for now), headers, stage 2 PROM, modded MAF, cat back, no catalytics, cowl hood, centerline champ 500 rims, KOBEL predator ground effects kit, Trans AM tailights, dash pouch, 92 shift console w/indicator, white face gauges, accented red trim, 12 speaker stereo, 4 amps, tint, T tops... icq 44373460 AIM:admrlam
see it at www.geocities.com/admrlam/bird.html

 

The TC lockup works like thus: A solonoid in front of the valvebody receives a signal to lockup (through certain requirements controlled by the ECM). The solonoid lets pressure from the pump into a certain area of the converter which engages a clutch which basically mechanically couples the engine to the driveline.
You can manually lock it by grounding the upper far-left pin of the ALDL, but I don't really recommend it.

admrlam is right, you would be worse off without it.. I don't have mine because I fried my VSS so the computer won't lock it because it always thinks it's not moving, and I'm pissed and I want my lockup back.

It's worth about 200-300 rpm when you're cruising, and that's a lot when it comes to mileage and longevity.

 

I had the same problem with my converter clutch locking up prematurely (due to a poorly programmed E-PROM) and it was quite annoying! So, what I did was, I spliced into the (tan/black stripe) wire coming directly from the ECM, this wire sends the signal to the solenoid in the pump (just like Jza said) to engage the converter clutch. By placing a toggle switch in-line you can engage the converter whenever you want. Until you get your chip programmed to your liking, this is a good fix, it's working for me. If you tell me the year of your car, I will verify the color of the wire coming from the ECM.

 

So my question is if you burn a new PROM to lockup the torque converter at a higher speed, wouldn't you still have that lock/unlock problem, as you're at the threshhold... only it would take place at a higher speed, instead of around 40??

How would this solve the locking/unlocking problem of the TCC?

Thanks.