Problem Sometimes In Reverse

[DA BIG ONE]

Sometimes, when I put tranny in reverse the motor revs up slightly blowing a cloud of black smoke, then is normal.

Any of you know what may cause this?

[markrinker]

Sounds like your transmission needs an adjustment to the apply clutch for reverse. I wouldn't wait - have been told many times that the 4L80E is a solid tranmission, but will break if you let 'sloppy' apply problems go un-adjusted.

The black smoke is unburned fuel as the IP is supplying too much fuel with no engine load and no boost yet spooled up to burn it. Fix the apply problem and I bet the smoke will stop. Similarly, my #2 truck with the Heath chip will blow a healthy cloud of black smoke only when warm by 'mashing' the pedal off idle - before there is any boost.

Both trucks have original 4L80E transmissions and have been shifted tens of thousands of times in and out of reverse snow plowing, but do not rev/slip at all going into (or out of) reverse.

Hope this comparison helps.

[DA BIG ONE]

Originally posted by Mark Rinker:
Sounds like your transmission needs an adjustment to the apply clutch for reverse. I wouldn't wait - have been told many times that the 4L80E is a solid tranmission, but will break if you let 'sloppy' apply problems go un-adjusted.

The black smoke is unburned fuel as the IP is supplying too much fuel with no engine load and no boost yet spooled up to burn it. Fix the apply problem and I bet the smoke will stop. Similarly, my #2 truck with the Heath chip will blow a healthy cloud of black smoke only when warm by 'mashing' the pedal off idle - before there is any boost.

Both trucks have original 4L80E transmissions and have been shifted tens of thousands of times in and out of reverse snow plowing, but do not rev/slip at all going into (or out of) reverse.

Hope this comparison helps. Is this adjustment easy? I ask because the tranny shop I normally use told me they could install a highend shift kit (towing), including all new upgraded HD shifting sollenoids for about $500. I can only guess this requires they remove the valvebody.

[markrinker]

Not sure if that would address the clutch apply problem, or not. If you have high miles and/or lots of towing miles, you may as well rebuild the clutch packs while the tranny is out of the vehicle. The shift kit could be done as well.

If they are suggesting an in-the-vehicle fix to your problems with a shift kit, I'd be leary.

[markrinker]

Not sure if that would address the clutch apply problem, or not. If you have high miles and/or lots of towing miles, you may as well rebuild the clutch packs while the tranny is out of the vehicle. The shift kit could be done as well.

If they are suggesting an in-the-vehicle fix to your problems with a shift kit, I'd be leary. How can they be sure that its only solenoids, without opening up the tranny?