74SpiT

Hey guys,

I have an 89 IROC 350TPI with the stock 700R4, and I am kinda puzzled about something. The transmission has a B&M shifter with no auto mode, and upshifts and accelerations are great. But as soon as you take your foot off the accelerator, the engine goes back down to idle and the car just "coasts", regardless of what gear or speed. If you downshift, it will drop a gear, but there is no way of telling unless you bring the revs up. There is no engagement or engine braking at all, and it is a little rough on the brakes after a while. Thing is, the previous owner put in a higher stall torque converter, but he couldn't remember if it was a 2000 or a 2500. I was under the impression that these stall speeds wouldn't affect drivability much, but is this "problem" just the nature of the converter?

Thanks for your time!

Barlow8869

iTrader: (1)

it sounds like the lock-up is not working ... you may be able to make it lock with the right volts to the right wires, but i couldnt tell you what the specs are for that

74SpiT

Thanks for the insight, I knew it had to be more than the high stall like I had been told before. I am looking into the TCC solenoid/wiring and I'll see what I find. If this tells you anything, i did a little experiment where I was in overdrive doing about 50-55 mph, and I could knock it down all the way into first with no resistance at all. The car just kept on rolling.... Feels like neutral the whole time.
The transmission was replaced by the previous owner so I'll see if everything's hooked up I guess. Thanks again!

RBob

iTrader: (1)

It is normal for the TCC to unlock on a coast ( 0 - 2% TPS).

In D4 (OD) the overrun clutches are off, so it is normal on a coast for the car to just roll on.

However, in D3, 2, or 1, the overrun clutches are supposed to be engaged, which would provide engine braking. Sounds like they aren't engaging.

RBob.

74SpiT

Thank you that sounds exactly like my problem! What could cause these clutches not to engage? Could it be related to the TCC solenoid not working or are they just fried? If I had to replace them, would that be a job better left to a transmission pro or are they somewhat accessible?
Thanks for the response!

Fred

cosmick

If shifting to OD doesn't get you full-auto shifting, then the VB has problems.
I've had 4L60Es disengage, but lift-throttle unlocking shouldn't ever happen at cruise.

74SpiT

Yes, in OD the auto shifting is non existent. If I put it in 4 it will start in first, but will not upshift. Thanks

74SpiT

I have the pan off now, what would be a good way to clean out the valve body? is carb cleaner ok?

74SpiT

Just in case anyone else has this same problem, I finally figured out why. It turns out that my valve body was a TCI aftermarket unit that has no "engine compression braking". Oh well. I guess ill put it back together!