32 MPG after tune-up

[Ike]

Would the same apply to an aftermarket torque converter with a lock up clutch? I guess my question is: Is the problem in the converter or upstream of it? Can this problem (excess slippage) be fixed by replacing the converter?

[Dan Vincent]

The problem is in the valve body of the transmission, NOT the torque converter. The valve body controls the lockup, and it's unable to make it lock up due to the leak. The clutch material is actually quite good on the 95 and up where this issue comes into play. Very rarely will the TCC be so worn on the 95-up 4L60E where it will be unable to apply, though this is possible.

This problem usually applies for 1995-2000 4L60Es with the pulse width modulated apply. If you're a post 2000, you have a better valve body with a better valve, though you can still get it (and a different kit is used, no reaming required.

[Ike]

Would an aftermarket shift kit (transgo) affect this in any way?

[Dan Vincent]

I believe the Transgo kits replace the valve, but aren't as extensive as the Sonnax kit (with a new sleeve, regulator, etc). I believe the transgo kits have a direct on/off TCC apply valve, but if your valve is worn, that won't fix it - you still need to get it reamed and re-sleeved. It would be good for preventative maintenance (got low mileage, although in our aging cars low mileage is a thing of the past), but it won't fix it if the problem exists.

[Silver 99 Camaro]

I had the TCC problem at 38,000 miles. Car would run as high as 3000 RPM at 70 MPH. I had it fixed with the Sonnax kit for a total of $325 including a fluid flush. I believe it's still a pulse width modulated valve, but it has worked perfect ever since. The key is not to wait until you get an error code, by then your torque converter is usually fried. Mine was showing some wear, but it was still ok because I caught it early. Watch those highway RPMS's!!!

[Dan Vincent]

Nah, I wouldn't worry about the converter unless you weren't going anywhere - that means the converter is fried ;) My car went six months, maybe even longer before it was fixed, mostly because I didn't know what was going on until last month (and even then I didn't have the cash to fix it).

[Silver 99 Camaro]

I went 6 months too. The guy at the tranny shop told me if you wait until the tranny slip code trips then 90% of the time the TC would be shot too. Because it is trying to lock up on the highway but the solenoid is not changing the pressure enough. So it slips the entire time heating up the fluid and friction material. My fluid was pretty well toasted after 6 months, with a lot of highway driving.

[jtigger]

Guess I've been lucky so far. One of the few F-body probs I haven't seen so far. Thanks for the info. I know what to lookout for(although I've been looking for a reason to get a higher stall TC)