88TAJeff

I've been chasing a 'jerkiness' gremlin lately, and I thought it was the motor after my cam swap. It does it at very mild throttle 800-1500 rpm. It seems to only do it after the motor shifts into 3rd and the T/C locks up. Today, I left the shifter in 2nd, and it didn't jerk at all under any conditions until it reached about 40 km/h, and then it felt like the T/C locked up. Is it supposed to lock up in 2nd? This is when it started jerking again. Why would it be jerking after the T/C locks up? is it a bad connection causing it to lock/ unlock ? Please help, I know nothing about trannies.
BTW, it's a 700R4. Thanks,
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams XR258HR, 206/212 @ 50 .480/.487 110 LSA everything else stock

JoelOl75

There's a pressure switch for 4th gear in the valvebody that grounds one side of the lockup soilnoid when the trans is in 4th gear.

This isn't on all models, but if it fails closed, it will cause lockup in all gears except 1st.

88TAJeff

Thanks, Joel. doing a search on this, it appears the TCC will lockup under light throttle conditions in 2,3, and 4th. even or a properly working tranny. Is this true?

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams XR258HR, 206/212 @ 50 .480/.487 110 LSA everything else stock

transfixleo

Yes.

88TAJeff

Ok. I know for sure now that my TCC lockup is the problem. When I'm in 3rd, and put the brake on a little bit, the TCC unlocks, and no more jerking. Lots of jerking when I take my foot off the brake again. It seems like the TCC is locking up when it's supposed to, so what would cause it to act like this. If it was a connection, wouldn't that cause it to sometimes not lockup?
Thanks,
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams XR258HR, 206/212 @ 50 .480/.487 110 LSA everything else stock

transfixleo

Actually that is not normally true. What happens is and engine missfire shows up more when there is a solid connection to the engine, instead of the dampening affect of the unlocked converter. This is usually worse in 4th.

You can try power braking to see if you can reproduce it or probably better yet, put a vacuum gauge on the engine and drive the car. If when it occurs the gauge starts to flutter badly then it is the engine, if not it is the tranny/convetrer.

88TAJeff

Hi. I finally got my hands on a vac gauge. When the car is doing it's jerky thing, the gauge is rock solid. Does this mean the prob. is in the converter? this is the only time I notice it. I have never used a vac gauge before, I hooked it up to the plenum. Is this alright? Thanks for your help.
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams XR258HR, 206/212 @ 50 .480/.487 110 LSA everything else stock