ok, if i am driving in drive and say im going 40 MPH and i let of the gas, and coast, then the Torque convertor will lock for like 1 sec and brings downt he RPMs, then it unlocks and the car is fine, then it will do it again. it does the same thing in OD at speeds from 40-60. any clues?

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88' GTA 350 MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass

 

the torque converter lock-up is controlled by the computer. It is supposed to lock up in 3rd and OD at speeds over 40 or so i think. Sounds like its functioning properly, however annoying. Aftermarket chips raise this lock-up so it happens at a higher speed.
The TC can also lock up in 2cd but on mine it only does it at the top of 2cd.

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'88 RS (originally 2.8)
-350, .040 over, vette alum. L98s, stock tpi.
-305 injectors & chip
-TES headers & edelbrock cat back
-3.73 gears, 700r4.
Best with 2.8-17.4@77mph
Best with 305-15.0@93mph
Best with 356-13.7@101mph
on a 2.050 60 ft.
(Damn the 2.8!)

 

so why does it only lock for a sec, cause i'll be going 60 on the highway, and then i'll let off the gas and be decelerating, and then all of a sudden the RPM's will drop by about 500 or more and you'l feel the car slowing (engine braking) and then it'l stop for a couple seconds and then do it again. is it normal for it to do that. it has a shift kit in it, and the tranny fluid looks a little burnt, but other then that, it doesn't slip or anything. but in the morning, when i first start it and take off, it does kinda feel weird, i have to give it gas, and then it it will kinda feel like it will stall, then it will catch and kinda jerk, but thats only when its cold.

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88' GTA 350 MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass

 

It's like on a car with a stick. Once the clutch is fully engaged, there is no slack or loss in the tranny and it has that kinda jerky ride when you are off the throttle or slowing down with the clutch in, or accellerating slowly.
When the TC is locked there is almost no loss in the tranny, and it behaves like the stick. The reason it jerks when you are decelerating at high speeds or just letting off the throttle and then back on is because the TC will not unlock till you hit the brakes or give it sufficient throttle.
This is the best i can explain it, it is normal behavior from your TC, and yes it gets annoying.
You may want to try to tighten the TV cable on the thottle lever going to the tranny. This will make the car shift a little higher, but will also delay TC lockup a little.
hope this helps.

 

Sorry, i misread your second post.
It actually sounds like your TC is locking and unlocking a high speeds. This could be a malfunction in the chip info(controls lockup speed and rpm) or the computer itself.
Do you have a scan tool to verify the TC is locking and unlocking, or are you going by feel and watching the rpms?
I can't advise you on what to do, just try to make sure the TC is doing that. It could be a vacuum leak, they tend to mess with the rpm during decelaration. I have one and it does exactly that.
I hope some of this helps since my last post probobly didn't!

 

thanks alot guys for your help, i'v been needing a reason to buy a scan tool, wut kinda should i get?

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88' GTA 350 MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass

 

A light "push & hold" on the brake pedal with your left foot will keep the TCC from locking up. Push the brake down just enough to turn on the brake lights; the TCC lockup is wired into the brake switch. When the brake lights come on, the TCC unlocks. You can use this to diagnose the TCC...

Your TPS might be mis-adjusted, too. The ECM monitors the TPS during lockup. If it senses you let off the pedal (closed throttle), it will unlock the TPS. If the ECM kept the torque convertor locked up, your gas mileage would go down- that's because of the "direct" engine-to-trans connection. By unlocking the TCC at low-rpm engine op, the trans freewheels, and you don't feel such a strong "engine braking" effect. Sorry I can't word it better... I skipped lunch.

So if your TPS is off adjustment, your ECM might not realize you've let off the gas. It might keep the TCC in lockup.


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-Tom P (Hot rodded 1986 Firebird 2.8l)