alian

Hey guys. I have just installed a a rebuilt 4L65e and a 3k stall into my Crewman and on some hyway testing I have found the following. The converter locks in great at 85kph (53mph) but after about 5mins on the hyway it seems to unlock and go back to 3rd. Temps are all good 195F max,
No DTCs have been logged, but we can overide and command 4th again with efi live.It is hard to work out wether the stall is unlockin 1st or we are loosing the signal and droping to 3rd which would unlock the converter. Once lost you can not get it back to 4th, tried playing with the shifter, adjusting speed of car, stopping and restarting car.
The funny thing is that while limping home we found 4th again so about 5mins of 4th followed by aprox 5mins of 3rd and so on. We have talked to the box builder (well known) but is 2000 km away and he says that it cant be the box.
So anybody out there got any ideas.
Cheers Ian

Vince B

iTrader: (1)

Look to see if you are having issues with engine misfires. These can cause issues like what you are describing.

alian

Ok Thanks , but shouldnt misfire throw up a DTC.code??I will have a look
Cheers Ian

bigmac108

I had the exact same problem in my 00 trans am. I figured out that i was getting a slip code from my transmission which makes the converter come out of lock up. My family owns a good size transmission shop and i am also a 4l60 builder. I could not figure this out because i even put in a whole different transmission and converter but i still had the exact same problem. The error was in the tuning parameters. I took the car back to they dyno shop and he swore that couldnt be the problem, but with some convincing he re-wrote the tune and i havent had a problem since. The converter could be slipping a little because of the lock up solenoid. somtimes they crack and lose a little pressure. Once the computer sees the slip then it quit's letting the converter lock up. Hope that helps

jimmyblue

iTrader: (11)

There is a "slip learning" algorithm that tries to pull
back TCC duty until the converter just "barely" slips.
I guess that saves a tiny bit of pump load for CAFE.
But being as the learning is slow and slip makes heat
and heat changes viscosity and viscosity changes
the TCC apply force, it's not too surprising that you
could exceed the slip-code threshold if you "surprise"
it - like, say, a long grade after running on flat land.

Seen this very thing. Full TCC duty full time is my
answer.

alian

Thanks for the info, After talking to a guy on the efilive forum we did some testing. We changed the hot mode lock and unlock rpms/speeds and while monitoring the TFT we have found to be able to keep it locked while driving.
Jimmyblue, It seems to happen with out any extra load looking at the logs refering to map . We are looking into the tune at the momment. I dont have the original tune but I am booked into Holden to get the original tune put in so I can start again from scratch.
Cheers Ian