06 Yukon 4l60E Not Shifting As Tuned

[SB2PRO]

Hello,
I am having a problem with the transmission shifting early on the 2 - 3 shift at WOT. It is not matching the tuned shift points. The computer is commanding it, so I wouldn't think it would be the transmission. The 1 - 2 shift is at about 40 mph and 5800 RPM, 2-3 is at 3900 rpm and 49 mph. It should be 67 mph or 6000 rpm. There are no codes set, but the vehicle has had a flashing service engine light occasionally. Any thoughts? I have attached the tune file and date log.

Thanks. 06YukonSamPaulNewEngineVE11MAF6ShftPnts.hpt06YukonSamPaulNewEngineVE11MAF6ShftPntsEarly2-3.hpl

[TransGo Robert]

Maybe something is not setup correctly in the tune, hopefully someone can help with that. It looks to me like the issue is caused by the slip you get on teh 1-2 shift, it goes so high that it commands the 2-3 thinking you are going fast enough for it but in reality it is just the driving wheel that are spinning.

[SB2PRO]

Maybe something is not setup correctly in the tune, hopefully someone can help with that. It looks to me like the issue is caused by the slip you get on teh 1-2 shift, it goes so high that it commands the 2-3 thinking you are going fast enough for it but in reality it is just the driving wheel that are spinning.

Thanks for the response, I do appreciate it. The vehicle is not spinning and the transmission seems locked up good in low gear. The wheel speed and rpm have not reached the commanded shift point for part throttle or WOT in any of the tables as far as I can tell, yet the PCM is commanding the shift. The TPS shows full throttle during the issue. I don't feel like it is a transmission issue since the shift is being commanded. It really has me baffled.

[TransGo Robert]

Thanks for the response, I do appreciate it. The vehicle is not spinning and the transmission seems locked up good in low gear. The wheel speed and rpm have not reached the commanded shift point for part throttle or WOT in any of the tables as far as I can tell, yet the PCM is commanding the shift. The TPS shows full throttle during the issue. I don't feel like it is a transmission issue since the shift is being commanded. It really has me baffled.

What is this if not tire spin?? Spin.png

[Alvin]

That looks like a tire chirp to me..

Try this.. See if it might help.06YukonSamPaulNewEngineVE11MAF6ShftPnts.Alvin.hpt

[SB2PRO]

What is this if not tire spin?? Spin.png

Yes, that is chirping the tires on the 1-2 shift, but rpm and vss is no where near high enough to reach the commanded shift points to go to 3rd. That's what seems strange.

[SB2PRO]

That looks like a tire chirp to me..

Try this.. See if it might help.06YukonSamPaulNewEngineVE11MAF6ShftPnts.Alvin.hpt

Thanks. I don't have HPTuners on this PC to look at the changes, but will check it out when I get back to my other laptop. If you can explain what you have changed, that would be great.

[TransGo Robert]

Yes, that is chirping the tires on the 1-2 shift, but rpm and vss is no where near high enough to reach the commanded shift points to go to 3rd. That's what seems strange.

Yea it is only for 3/4 of a seconds so it is probably not that, but I thought it might be since it only does the early 2-3 when this happens. My theory was that the computer seeing the rate of acceleration predicted it would need to shift it in another 1/4 seconds because it would reach the output shaft speed set to shift 2-3 in your tune. Long shot, I really don't know if that even possible but I figured I would mention it just in case that's all it was.

[SB2PRO]

Yea it is only for 3/4 of a seconds so it is probably not that, but I thought it might be since it only does the early 2-3 when this happens. My theory was that the computer seeing the rate of acceleration predicted it would need to shift it in another 1/4 seconds because it would reach the output shaft speed set to shift 2-3 in your tune. Long shot, I really don't know if that even possible but I figured I would mention it just in case that's all it was.

Thanks for the input. When I get back in tommorrow I will revist the issue. Anything is worth a shot at this point.

[Alvin]

Thanks. I don't have HPTuners on this PC to look at the changes, but will check it out when I get back to my other laptop. If you can explain what you have changed, that would be great.

just try it

[SB2PRO]

just try it

No luck. Same thing. I am wondering if it has other issues that could cause the PCM to command a way early shift from 2 to 3? I am getting an occasional flashing service engine light and several of the other modules have codes set. (I don't know what those codes are). No codes in the PCM though. thanks for your input. I really appreciate it.

[Alvin]

No luck. Same thing. I am wondering if it has other issues that could cause the PCM to command a way early shift from 2 to 3? I am getting an occasional flashing service engine light and several of the other modules have codes set. (I don't know what those codes are). No codes in the PCM though. thanks for your input. I really appreciate it.

Traction control can force upshifts. Prehaps that is it.

[SB2PRO]

Traction control can force upshifts. Prehaps that is it.

You may be correct on that. He has several non-PCM codes and at one point I saw a no traction control indicator light up when it hadn't been manually disabled or even messed with. I sent him away to get his other codes and issues resolved and then we will see where the issue stands. Part of the time it would shift correctly and would pull all the way through 2nd gear. Other times it wouldn't. I wouldn't think that would be anything to do with tuning. Thanks for your help.

[2xLS1]

Flashing SES is detecting misfiring. Misfire detection can cause all kinds of weird issues trying to prevent cat damage. Fix that or zero out the MF tables and test that.

[Alvin]

Flashing SES is detecting misfiring. Misfire detection can cause all kinds of weird issues trying to prevent cat damage. Fix that or zero out the MF tables and test that.

I agree with this also.

[SB2PRO]

Flashing SES is detecting misfiring. Misfire detection can cause all kinds of weird issues trying to prevent cat damage. Fix that or zero out the MF tables and test that.

I had read that the flashing SES could be a result of misfires and a host of other things. I told the owner he needed to resolve his code issues and that his shift issue may be related. I did scan misfires and didn't see anything other than a few random low rpm misfires which I attributed to the cam. I never heard any obvious misfires, but who knows. This vehicle has had a frame off restoration with the frame being powder coated. I has had all kinds of ground related problems. I appreciate your input. Thanks

[edcmat-l1]

I had read that the flashing SES could be a result of misfires and a host of other things. I told the owner he needed to resolve his code issues and that his shift issue may be related. I did scan misfires and didn't see anything other than a few random low rpm misfires which I attributed to the cam. I never heard any obvious misfires, but who knows. This vehicle has had a frame off restoration with the frame being powder coated. I has had all kinds of ground related problems. I appreciate your input. Thanks

Flashing CEL is caused by "Potentially catalyst damaging massive misfire". About the only other thing that will cause a flashing CEL is a big lumpy cam that causes the PCM to believe it has a massive misfire.

[SB2PRO]

Flashing CEL is caused by "Potentially catalyst damaging massive misfire". About the only other thing that will cause a flashing CEL is a big lumpy cam that causes the PCM to believe it has a massive misfire.

The cam is not large and the engine sounds good. I told the owner to pull all the plugs and inspect them for differences and to check the plug wires as a start.

[Alvin]

The cam is not large and the engine sounds good. I told the owner to pull all the plugs and inspect them for differences and to check the plug wires as a start.

If it has a cam at all it will need the misfire stuff desensitized at the very least. I've even had stock LS6 cams trip it off in a 5.3L for example.

[2xLS1]

Never understood why people ask for advise on a forum and then ignore it. It would just take a minute to zero out the misfire tables and test it. If that isn't it then put them back. Then even if it is a real misfire it won't detect it.