Frustrating TCM Gremlin I'm out of enthusiasm

[MN C5]

Background; I installed a 6L90e in a 08 VMax that came with a 4L70e. After a few small issues I got it sorted out and it worked well. But one fine day the TQ converter stopped locking up. Not all the time, it seemed to have a mind of its own. It would lock up 10-15% of the time tops but usually only after a restart of the engine. Meaning I'd drive it somewhere shut it off and the TQ would engauge after starting it. That didn't mean it would stay engauged though. So after scanning it, I find the TCM isn't commanding the TQ lock up. (This is with the stock GM file) I was thinking of replacing the TCM but my friendly GM tech says the the ECM commands the lock up. But I think the ECM provides the signals for RPM, TP, and MAP. Even though EFI doesn't have a MAP reference table for shifting I think it is a variable in shifting and TQ lock up. As playing with VVT can really mess with the shifts via causing the TVS bypass to close and build boost at very light throttle.

The tech I'm working with says he has never seen a bad TCM so he doubts thats the issue but I'm not sure what else it could be. I'm using a 08 GMC Denali PU Vin and OS. I reflashed the BCM (No effect), and was thinking of reflashing the Gauge Cluster. But the fact that it worked fine for a few months has me puzzled. The GM tech line was very helpful but couldn't offer any options that worked either.

That's the end of my Rant..

Thanks

[GAMEOVER]

Wow!!!...A 6L90E in a 2008 VMAX

[joecar]

Look at the TSTATE pids... one or two of them indicate the reasons while TCC is not being commanded.

Are you getting misfires logged...? These will prevent TCC from being commanded.

You changed trans and TC... i.e. rotating mass seen by motor/ECM is now different, so you should probably do a CASE relearn to resync the misfire algorithm.

[MN C5]

Look at the TSTATE pids... one or two of them indicate the reasons while TCC is not being commanded.

Are you getting misfires logged...? These will prevent TCC from being commanded.

You changed trans and TC... i.e. rotating mass seen by motor/ECM is now different, so you should probably do a CASE relearn to resync the misfire algorithm.

I'm not familiar with TSTATE pids. I'll have to get myself up to speed.

Yes I'm getting misfires (Mild Cam) but I have the code shut off (Not Reported) in the program. That should do it right...

I had to do a crank relearn each time I changed OS's but I'm not recalling ever doing a CASE relearn.

Thanks for the tips Joe, I'll report back tomorrow.

[joecar]

As long as the misfire counts are staying pretty much steady (not increasing).

Oh, CASE relearn == crank relearn.

[ScarabEpic22]

I hope you get this figured out man, I cant offer any suggestions other than what you've already done. I do know that any misfires will not allow TCC lockup (like joecar said).

Jealous you can make the ECM and TCM OSs match up, Id love to do this swap into a TBSS because the 4L70Es get eaten up by the LS2+AWD combo and 6spd with TUTD would rock. Only 1 E67/T43 combo, CTS-V with a different OS and Segments IIRC :(. Custom T43 OS anyone?

[gmh308]

I hope you get this figured out man, I cant offer any suggestions other than what you've already done. I do know that any misfires will not allow TCC lockup (like joecar said).

Jealous you can make the ECM and TCM OSs match up, Id love to do this swap into a TBSS because the 4L70Es get eaten up by the LS2+AWD combo and 6spd with TUTD would rock. Only 1 E67/T43 combo, CTS-V with a different OS and Segments IIRC :(. Custom T43 OS anyone?

Looks like I can consider myself very lucky to have a 6L90 behind an LS in an early Camaro, working AOK. A real challenge to do this in a truck! :shock:

[ScarabEpic22]

Looks like I can consider myself very lucky to have a 6L90 behind an LS in an early Camaro, working AOK. A real challenge to do this in a truck! :shock:

Yep, but you're lucky you got setup your own wiring harness, we have to beat GMs into submission! Which is getting harder and harder as everything becomes more integrated.

[MN C5]

I feel dumb posting this but after 3 days of everything working perfectly I though I'd report.

The solution........... was in the ECM, simply install 0 for a value in the VVT tables (low, med, high baro) and whalla the issue was gone. Along with it erratic timing @ WOT smoothed to glass.. I'm not sure why but at least its fixed.

Now I just need to know what to do with the pressure and shift time tables. Anyone have a TCM file from a new CTS-V with the 6L90e?

[ScarabEpic22]

Good to know, it will help me out in the future when I attempt the 6L90E into my TBSS. I hope someone beats me to it because mine will be a few years away (unless I go through too many trannys in the mean time).

So what happens to VVT, simply keeps the cams at 0deg all the time?

[joecar]

MN C5, good job...:cheers:...thanks for the feedback... maybe someone will figure out why that works.

[RonC]

I would think that " 0 " in the VVT tables would lead to less than ideal performance. Obviously it works though, but it leaves the cam max advanced with low spark timing. I would suggest to try putting the stock low baro VVT tables in all three baro tables to eliminate the "EGR" effect that is in the med and hi tables and see if it still will lockup. If it does I would then zero out the cam phaser timing table and see what happens. If it still will lockup, then you can redo your timing tables for max timing without having to deal with these variables. That should take care of your erratic timing problems which may be the real cause. This works in mine and the timing is smooth and consistant. Hope this helps.

[MN C5]

I would think that " 0 " in the VVT tables would lead to less than ideal performance. Obviously it works though, but it leaves the cam max advanced with low spark timing. I would suggest to try putting the stock low baro VVT tables in all three baro tables to eliminate the "EGR" effect that is in the med and hi tables and see if it still will lockup. If it does I would then zero out the cam phaser timing table and see what happens. If it still will lockup, then you can redo your timing tables for max timing without having to deal with these variables. That should take care of your erratic timing problems which may be the real cause. This works in mine and the timing is smooth and consistant. Hope this helps.

I've got a cam and blower on mine. The values I had in the VVT tables were a fair bit lower than stock already as the Supercharger bypass was affected by the amount of retard in the cam position. The cam phaser values have been at 0 always.

Thanks for your input..