Weird Shifting Issue

[mcalicott]

Ok so I have a 2015 SS, it has a cam, I had it tuned recently and has started shifting weird.



A little backstory, 3 months ago it was hesitating to shift between 2nd and 3rd and even slipped out of gear completely a couple times. I took it to a transmission shop and they changed the fluid and filter and it seemed to go away, and no more slips.



So then I get it tuned, works great until about a week later. I start hearing this whining noise when it gets ready to shift (torque converter?) from time to time. At 41mph exactly every time it nose dives, revs up about 500rpm and then shifts. Does the same thing around 70mph. I take it back to the tuner who is a friend of mine and we do some pulls and he changes a few things and it doesn't do it anymore at 41 mph.



Now, instead of doing that at 41mph, at around 55 mph it refuses to shift. It will just rev up, try to shift, rpm drop, rev up, try to shift. This is all in normal Drive. Just testing some things out I figured this out.. if you put it in sport mode and use the paddle shifters it has no problems. Up to 55 mph in drive is fine. In sport mode without the paddle shifters it will not shift from 2nd, it just hangs. So I played around with it and figured out if I do it in Drive and shift it into sport at around 50, it has no issues.



I've talked it over with 2 buddies of mine that are mechanics, they have drove it and aren't sure what to make of it. My tuner said he can take a look at it but I don't want to bother him if it's not truly something with the tune and it's the torque converter. But even he said it was weird and he's never seen a Camaro do that. He did say that the default transmission fill level for Camaros is lower than it actually needs and he would try overfilling it. That he's seen lots of his customers that have had to do that to fix hard shifting and other issues. I'm worried its the torque converter but honestly just curious if anyone here has come across anything like this before or has any suggestions before I start throwing money at it.

[1JEWLDSSRS]

Read through this. It's possible you may be having an issue with your pressure switches. If one or more go bad you would most likely get a code stating the switch malfunction, but if the laminates/diaphrams crack or break like mine did, it will cause some shift flares and other shifting issues. Here is what mine looked like. 3 of them were cracked or broken.



https://www.sonnax.com/tech_resource...m-applications

[1JEWLDSSRS]

This is what they are supposed to look like.

[mcalicott]

Originally Posted by 1JEWLDSSRS

Read through this. It's possible you may be having an issue with your pressure switches. If one or more go bad you would most likely get a code stating the switch malfunction, but if the laminates/diaphrams crack or break like mine did, it will cause some shift flares and other shifting issues. Here is what mine looked like. 3 of them were cracked or broken.

Attachment 1126940

https://www.sonnax.com/tech_resource...m-applications

I will check that out thank you!


UPDATE: we got a chance to look at it this weekend and found that the transmission was actually 2-1/2 quarts low. There was a repair done on one of the trans fluid lines that had a slow leak. Fixed the leak and topped off with fluid. All issues are gone now except the weird shift at around 55mph. I let my mechanic buddy drive it and he said it is dropping to neutral for a split second when it tries to shift. But it does shift, just has a little neutral drop still. I’ll check the pressure switch thing out, we were thinking that might be what it was. Also I think once I get that fixed if that’s the issue I need to get it re tuned. He has tweaked my original tune to try and change the shift points etc to work around the original neutral shift drop at 41mph.

[1JEWLDSSRS]

Originally Posted by mcalicott

I will check that out thank you!


UPDATE: we got a chance to look at it this weekend and found that the transmission was actually 2-1/2 quarts low. There was a repair done on one of the trans fluid lines that had a slow leak. Fixed the leak and topped off with fluid. All issues are gone now except the weird shift at around 55mph. I let my mechanic buddy drive it and he said it is dropping to neutral for a split second when it tries to shift. But it does shift, just has a little neutral drop still. I’ll check the pressure switch thing out, we were thinking that might be what it was. Also I think once I get that fixed if that’s the issue I need to get it re tuned. He has tweaked my original tune to try and change the shift points etc to work around the original neutral shift drop at 41mph.

When we did the replacement of my laminates, and the output/input speed sensors which was what my issues was, my tech said a "retune" was not needed. He was right as the trans operates just like it did before the work, only BETTER!! lol. Here is a vid of the TEHCM pressure switches rebuild, got all my parts needed from SONNAX.

[mcalicott]

Originally Posted by 1JEWLDSSRS

When we did the replacement of my laminates, and the output/input speed sensors which was what my issues was, my tech said a "retune" was not needed. He was right as the trans operates just like it did before the work, only BETTER!! lol. Here is a vid of the TEHCM pressure switches rebuild, got all my parts needed from SONNAX.

Awesome thanks again for all the info. Will update soon

[1JEWLDSSRS]

You are welcome. Good luck.