Loosing 4th once converter is locked

[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 95c max,
No DTCs have been logged, but we can overide and command 4th 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 as it happens at the same time. 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(as in it just started working 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 over a1000 km away and he says that it cant be the box.
So anybody out there got any ideas.
Cheers Ian

[Taz]

Post your tune when you get a chance … will take a look.

Was the original transmission also a 4L60/65/70 variant ? I take this problem just presented itself after the install of the “new” 4L65.

Any changes to the tune made concurrently with the installation of the transmission ?


Regards,
Taz

[alian]

Taz. Yep it was a 4l65e that came out aswell. I had never had this problem before the install. The only chages to the tune was lock up speeds and some pressure changes. I dont have a std tune to compare but I have the car booked into Holden on Friday to have the std tune installed. I will then save it my laptop and start again just incase I have a problem somewhere that I cant put my finger on. I will post tune as soon as I have worked out how to do it.
Ian

[alian]

File attached.

[Taz]

Hello Ian,

The attached tune should be considered for diagnostic purposes only - wondering if there may be an issue with the TFT sensor. I eliminated the “Hot mode” shift behaviour in the 3>4 and 4>3 PT portion of the TCM tune. Also adjusted the 4th gear TCC apply / release parameters - to also eliminate the “Hot mode”.

If this helps, then the issue is probably the TFT sensor.


Regards,
Taz

[alian]

Thanks mate, I get what you have done, great thinking. I was going to test it today but it is pissing down rain and have had to get over to the workshop to clean as we have a little cyclone that is supposed to hit late tonight. I will test tomorrow.
Cheers Ian

[alian]

By the way is there a pid for what state the auto is in??, NORMAL,PATTERN "A", "B" or HOT State .This would confirm that is going into hot state.
Cheers Ian

[alian]

Ok, did the testing, and it came back that with the new settings it didnt loose 4th at all. The TFTs are steady at 95C so what would be throwing the tranny into hot mode if the temps are ok. Or is there a setting that you can set where the hot setting cuts in. Has any one out there have any idea if there is a pid to monitor tranny mode. NORMAL,PATTERN "A", "B" or HOT State.
Cheers Ian

[Taz]

Glad to hear the “new” transmission shifts OK with the modified tune. You stated your temps were steady at 95C (203F).

Is that the engine coolant temp or the TFT (transmission fluid temperature) ? If 95C refers to coolant temp, that is normal. If that is the TFT - that seems too hot - generally don’t like to see this value over 75C. Not sure if TFT in the 95C range are common in your climate - still seems a little too hot.

I’m on the road for the day - no access to manuals or tuning software. Will try and check for PIDs and the threshold for “Hot mode” when I get home this evening.


Regards,
Taz

[alian]

Thanks. That is TFT . I have gone over all my logs from when I started 3 years ago and have always seen up arround 93degC tranny temp. I now have a stall converter fitted but have also fitted a tranny cooler to help.
Cheers Ian