[greggshere]

So I'm not sure if this is an issue or not, so I'll just ask if anyone else experiences this. When the car is in Rev Match mode, sometimes when I upshift from 1st to second the engine rpm does not decrease during the shift. I let off on the gas just like any other time when I shift, but the rpm does not drop for that short instance. It does not do it every time, but it does do it most of the time, say 3 out of 5 times. It never has done it with Rev Match off, nor any other gear shift. Always 1st to 2nd and always when I am in Rev Match. I love running in Rev Match but that rev during the 1st - 2nd shift is annoying, as it makes for a jerky shift. Anyone else see this?

 

[mjw930]

I've experienced that but as far as I recall, only on leisurely acceleration. Try a 1st to 3rd shift in these situations and see if it still refuses to drop revs.

 

[Mobius]

So I'm not sure if this is an issue or not, so I'll just ask if anyone else experiences this. When the car is in Rev Match mode, sometimes when I upshift from 1st to second the engine rpm does not decrease during the shift. I let off on the gas just like any other time when I shift, but the rpm does not drop for that short instance. It does not do it every time, but it does do it most of the time, say 3 out of 5 times. It never has done it with Rev Match off, nor any other gear shift. Always 1st to 2nd and always when I am in Rev Match. I love running in Rev Match but that rev during the 1st - 2nd shift is annoying, as it makes for a jerky shift. Anyone else see this?

I have experienced this as well. One common thread seems to be that those who encounter this have a CAGS bypass* (either through hardware or software).

The issue seems to be RPM dependent and possibly speed dependent.

I plan to remove my CAGS bypass for a week to see if I can reproduce the issue without the bypass. This will confirm if CAGS is somehow involved. I'll follow-up with my findings.

http://www.stingrayforums.com/forum/stingray-corvette-problems-issues/1950-some-issues-i-am-seeing-26.html#post88040

http://www.stingrayforums.com/forum/stingray-corvette-problems-issues/6863-c-7-rev-match-shifting.html#post88374

*correlation does not necessarily indicate causation

 

[greggshere]

Interesting, as I do have a Cags eliminator. I'm glad I do, as I do see the message come up quite a bit, since we have a lot of bumper to bumper traffic around in this college town. If the Cags does indeed play into it, I will live with it, because I love the Cags. I only want to shift when and where I want. I have tryed to notice if it does the Rev issue when I am creeping through the gears vs, spirited and it does not seem to matter. It does it both ways from what I can tell. I've gotten to where I put it in Rev Match when I'm going to downshift, then turn it back off for the upshift then the issue doesn't occur at all.

 

[Dasyatis]

I get the same though not all the time. I've gone to turning the rev match off when starting from a dead stop. I don't have the CAGS eliminator per se though I did change one parameter with tuning software so that is will not be activated, no CAGS no dash indication so that piece of software should not be active when driving.

 

[Boomer]

One common thread seems to be that those who encounter this have a CAGS bypass

CAGS bypass. Gosh, just another example why I don't do mods... my list is getting so long..

 

[greggshere]

Based on what Dasyatis just said it appears to be coincidental that Cags are on some cars exhibiting the behavior, his doesn't have one. If indeed it does play into I can live with it, because I would not be able to live with the skip shift feature.

 

[rdslon01]

Dasyatis does have a CAGS eliminator: his is done through a software tune, not a hardware addition to the car. See "Art's Build Thread" where I think he talked about it.

Let me see if I can find that...

 

[rdslon01]

See post #7 here: http://www.stingrayforums.com/forum/stingray-build-section/2344-art-s-c7-z51-build-thread.html

 

[greggshere]

I would think that bypassing Skip Shift using a software fix would be less likely to affect things than my cheap hardware bypass, but that's just me thinking out loud. It would be interesting to know if anyone without Cags Eliminator has experienced the occassional Rev Match 1st - 2nd rpm no-drop though. Also, I would think if the Cags Eliminator was the culprit it would do it every time, but for me it just seems to do it occassionally, whether or not I get the skip shift message or if I'm driving spirited. Anyway, even if it is Eliminator induced I'll live with it, since I don't want Skip Shift. Turning off Rev Match during the 1-2 upshift is easily accomplished with the paddles.

 

[Curahee]

I would think that bypassing Skip Shift using a software fix would be less likely to affect things than my cheap hardware bypass, but that's just me thinking out loud. It would be interesting to know if anyone without Cags Eliminator has experienced the occassional Rev Match 1st - 2nd rpm no-drop though. Also, I would think if the Cags Eliminator was the culprit it would do it every time, but for me it just seems to do it occassionally, whether or not I get the skip shift message or if I'm driving spirited. Anyway, even if it is Eliminator induced I'll live with it, since I don't want Skip Shift. Turning off Rev Match during the 1-2 upshift is easily accomplished with the paddles.

I do not have a CAGS eliminator and do experience the rpm no-drop once in a while. It seems to happen mainly after getting above 2,500 rpm in first gear. Does not happen with more gentle launch. I just live with it by going first-to-third if I catch it in time.

 

[rdslon01]

I do not have a CAGS eliminator and do experience the rpm no-drop once in a while. It seems to happen mainly after getting above 2,500 rpm in first gear. Does not happen with more gentle launch. I just live with it by going first-to-third if I catch it in time.

Great information!

There you have it Gregg: you were indeed correct that the CAGS eliminator is just a red herring and not an actual contributor.

 

[Mobius]

We still need to determine if there is a fix for this issue... I'm still looking after ~2 years.

I installed an MGW shifter in late 2014, and I hoped that the freshly installed and aligned MGW shifter might eliminate the issue - nope, same as before.

The issue can occur with or without a CAGS bypass installed, as posted above.

Anyone have any new ideas on how to correct this? Some M7 pilots claim they don't encounter it.

Does it still happen with the 2016s and 2017s (?) - let us know, and thanks in advance.

 

[Petercwelch]

Not designed to work below a certain speed.

 

[Mobius]

Not designed to work below a certain speed.

Are you driving an M7, and is that a guess or something you' have insight on?

That does bring up an interesting question... if we were to look at the Rev Match parameters using tuning software, what parameters (if any) would be adjustable...

 

[JoeCT]

I have a '16 and use rev match almost 100% unless I forget to turn it on (which I am quickly reminded of at next low gear shift). I'm at nearly 10k miles, I've never experienced this and I've pay quite close attention to the 1-2 shift because I've been trying since new to find a pattern (rpm, clutch, speed) that makes it smooth with no crunch.

On that latter point, I realized I had developed a bad habit of running 1st up to higher rpm than necessary in response to trying to avoid the skip shift. I've stopped doing that and my cold 1-2 shift is much much better now. Frankly, the skip shift doesn't happen enough to be that big a problem for me. At my last service a couple weeks ago, I mentioned the tough 1-2 shift for the second time since owning the car. Paul Koerner is the specialist at my dealer (I do feel lucky) and he had mentioned early on that the shift seemed normal and that by this mileage it ought to even improve. On this latest visit, he did check and adjust to make sure neutral detents (my words) were correct but that was the only change. I'm happy and a bit surprised to say it's shifting just fine. I don't know if its mileage on the tranny, the adjustments, my skills (doubtful) or just the corvette gods rewarding patience but it's good.

Hoping for some more nice fall days here in New England.

 

[Mobius]

I have a '16 and use rev match almost 100% unless I forget to turn it on (which I am quickly reminded of at next low gear shift). I'm at nearly 10k miles, I've never experienced this and I've pay quite close attention to the 1-2 shift because I've been trying since new to find a pattern (rpm, clutch, speed) that makes it smooth with no crunch....On this latest visit, he did check and adjust to make sure neutral detents (my words) were correct...

Thanks for the info, and I'm glad you're not encountering this issue.

When you mention that your mechanic checked and adjusted the neutral detents, are you referring to adjusting and centering of the stick?

 

[Petercwelch]

Think I recall a bit in the manual about parameters for rev match. I do have an M7

 

[Petercwelch]

Not active below 20 MPH as per 9-33 in 2015 manual.

 

[Mobius]

Not active below 20 MPH as per 9-33 in 2015 manual.

Yes, that's true (for 2014-2015 models), but let's say you're shifting from 1st to 2nd at less than 20 MPH (and Rev Match in inactive because of it), why would RPM be held - it should decline.

Also, when the phenomena occurs (randomly, it seems to me) and you also release pressure on the accelerator after the shift, RPM can take a full second to begin dropping. And this is only on upshift between 1st an 2nd...

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It is also interesting to note that in 2016 the Rev Match activation speed was reduced to 9 MPH...

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And then in 2017 the Rev Match activation speed was increased to 16 MPH...

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