I'm trying to diagnose a problem with a friends 94z. I'm an M6 guy and don't have a lot of experience with the A4's so bear with me. This car is a bone stock 94Z with an A4. He says it drive and shifts fine on the street. But, at the track it won't shift out of 1st. Hit's the rev limiter apparantly. I scanned the trans data and found no error coded or obvious issues. He thinks its a PCM issue, I'm kinda convinced it's mechanical. Got any ideas?? Anything specific I should look for on Datamaster?

Thanks

Clueless

 

did he try to go through the gears manually mine did that if i left it in drive or overdrive it would go fine but trying to go through the gears it would try to pull but slip and pop the rev limiter.Since then on a hard launch i only have two gears.Theres a guy on here named frank from CPT a tranny shop in Deleware he know his $hit when it comes to the 4l60e but from what ive read and what ive experinced tell youre buddy his tranny is done cause a bone stock 4l60e sucks.

 

did he try to go through the gears manually mine did that if i left it in drive or overdrive it would go fine but trying to go through the gears it would try to pull but slip and pop the rev limiter.Since then on a hard launch i only have two gears.Theres a guy on here named frank from CPT a tranny shop in Deleware he know his $hit when it comes to the 4l60e but from what ive read and what ive experinced tell youre buddy his tranny is done cause a bone stock 4l60e sucks.

 

This is usually a result of the 2-4 band not holding at higher RPM's. This is partially due to the fact that the 4L60E is designed (from the factory) to start dropping pressure at 5000 RPM's.

There are several modifications that we do to prevent this from occuring.

It's a common complaint to see a 4L60E bump the limiter on the 1-2 and/or 2-3 shift before we build them.

In other words...Yes, this is probably an internal problem.

Frank
CPT

 

This guy says that it won't shift from 1st to 2nd at the track even if he shifts manually. I'm still pretty sure it's a trans problem. Any thing I can scan and log on a run to help confirm mechanical vs PCM/sensor issue? I hate to tell the guy to yank the trans only to find out it's something simple like a broken wire or bad sensor. How much line pressure should I see at WOT through the shifts?


Steve

 

The question on my mind:
Is he stalled with a converter at or over 3000?
If so, and hes not fixed up the computer, he has the OBD I high stall problem. It apparently is fixable, ,more info on it can be found in the computer section of the board
If hes on a stock stall, a properly running trans should not be missing the 1-2 shift, rebuild time!

 

It's a stock converter. That was the 1st question I asked him also. I have a ton to learn about automatics but, besides "just a bad tranny", what's the most probable technical reason for the late shifts? Shouldn't the PCM comand a shift at a RPM off the trans tables. Is it that the PCM is comanding a shift but the trans can't execute because of servo's , pressures, etc??

Steve

 

Thats exactly what my tranny is doing right now It started doing this in the 1-2 shift a little bit after doing my headers/gears swap but once I had the engine built with the 503 cam 1-2 and 2-3 will hit the rev limiter a couple of times before going to the next gear. I added about .5 pint over the max fluid level on the dipstick and this has ridded of most of the problem but I still get a missed shift here and there. I may just make a winter project of building the trans while the car is being stored this next winter (Then I can finally get the appropriate converter to really wake my car up ).

 

Yes, the computer is commanding the shifts, but the transmission is failing (mechanically and hydraulically). The stock 4L60E doesn't have enough pressure at high RPM's, nor does it have enough holding power for the 2-4 band or the 3-4 clutches.

Frank
CPT