Azrael

iTrader: (10)

We are running a Performabuilt Level 3 4L60/65E with a Performabuilt 4K stall behind a LSX 454ci stroker. The combo is a few years old but only has about 5k miles on it.

The issue: no overdrive. The car drives fine in the first 3 gears, but when it goes to shift into OD is drives like it is in third gear until you let out of the throttle then the RPMs drop like it is in OD. If we get back on the throttle it is like it is third gear again. There is no slippage, as in the RPM doesn't climb without accelerating, it just seems never to go in OD with any throttle, but will act like it is in OD while decelerating or coasting. In third the car drives normal, all other gears seem strong. This transmission is 4 years old, with low mileage (5k miles)... I almost thought it might be something with the converter not locking; as our tune calls the converter to lock only in OD at speeds above 60 mph.

I figured it was time for a 4L80E anyway, since the trans is our weak link in the drivetrain with the backbraced Moser 9". This transmission has only been behind the stroker and not seen any spray while behind the 454 (although the engine is built to be nitrous fed). Frank stated this transmission would be good for around 800 rw, and our car unlocked only puts out about 580/530 just on motor.

Any insight on what the problem may be would be greatly appreciated. Money is tight right now, so it would help not to have to replace this transmission if it is just a tuning or less expensive converter issue.

Although, it will have to go regardless, when the final nitrous system is plumbed; as we will be north of its highest recommended torque/horsepower rating.

z28camaro82z

It wouldn't hurt to have a tuner look at it considering there has been some substantial modification. I would start there. The transmission is computer controlled and it sounds to me like the problem is likely in the command. If it were a band failure you would see the problem in second gear as well, and if it were a 3-4 pack, well 3rd gear wouldn't be as solid as you make it sound. Sounds like a phantom issue, I'd have a reputable tuner share his opinion and take it from there.

Azrael

iTrader: (10)

Awesome, thanks for the response. Never been that well versed on transmissions, especially automatics. The car runs well in every gear just never seems to go into OD, except when coasting/slowing but then pulls like it is in third gear strong. The car runs strong in all but the phantom OD. We had it tuned and it was working fine, then one trip home from work and OD just disappeared. I will have the tune looked at!

Ls1 6.0 2500

Hey guys, I have a similar problem with my 4l80 in my 1999 silverado 2500 except my trans will shift into overdrive on highway but will slip out into the passing gear and won't go back into overdrive until I slow down or stop and it down shifts and goes through the gears when i am accelerating, when it down shifts no codes are thrown but if when it kicks out and I continue to keep my revs to 2600 rpm the engine light will blink continuously and no codes show up on the code reader.. But get this, recently I figured out when I have my code reader plugged in on the fly and if I hit the delete DTC button as soon as it drops out of over drive it will kick back in for another 10 mins or so. Does any ones know what is going on? Is it the PCM or is it the trans it's self?
Thanks

SS SLP2

iTrader: (8)

"...had it tuned and it was working fine, then one trip home from work and OD just disappeared."

DON'T think problem is in tune "..and it was working fine ..."tune will not just change.

just my .02s Johnny