So I purchased my M7 2017 Z06 Z07 about 6 months ago out of Miami (I currently live in Indiana). The car had around 54,000 miles and overall I’d call it about an 8/10 condition.



On the test drive, I immediately noticed something off with the auto rev match. At lower RPMs it does a weird double blip instead of a clean, single throttle blip. The previous owner mentioned it had done that the entire time he owned it (about 6,000 miles), but coming from my previous M7 2014 Z51, I knew that wasn’t normal. That car’s rev match was always smooth and precise, so this stood out right away.



Fast forward to now, the car has been amazing in every other aspect. It drives great, shifts perfectly, and overall has been a fantastic car. The only lingering issue is the rev match still not behaving correctly.



For reference, the car currently has a DSX lid, Chevrolet Performance CAI, Texas Speed headers and X-pipe, Cordes Performance ice box, Mighty Mouse catch can, and an MGW shifter.



Since owning it, I’ve also added a DSX flex fuel sensor and a DSX aux pump. Not sure if any of that is relevant, but I figured I’d include everything.



About a month ago, I took it to a well-known Corvette tuner here in the Indianapolis area. On an E56 blend, the car made 667 WHP. I brought up the rev match issue to him, and he verified the stock mapping in that area while building out the rest of the tune. The car runs excellent now, but the rev match issue is still unchanged.



I’ve also checked the spark plugs, and they all look healthy.



One other thing I discovered was that the car had a 91mm Soler throttle body installed. I’ve since swapped it back to the stock 87mm throttle body, but that made no difference either.



At this point, I’m kind of out of ideas.



Is this something that needs to be specifically dialed in through tuning at lower RPM, or am I chasing the wrong thing entirely, like a sensor or input issue?



Appreciate any insight, thanks for taking the time to read.

 

This may be unrelated to your issue, but my ZO6 will sometimes do an unexpected blip if I linger in neutral at all during a shift. I find that holding the lever over into the 5-6 neutral gate will usually prevent it.

 

I know exactly what you’re talking about, sadly this issue is definitely not that. Because my previous Corvette would do that and this one is nothing like that. It’s almost like it’s struggling to get RPMs. Which might not even be related to the rev match. It just has a hard time climbing into that first three grand if you just give it a little blip on the throttle.

 

What is the result of this problem? An extra throttle burst? I sometimes hear that on my Z06 when driving at slow speeds and downshifting. I don't see it being an issue, other than it might waste an extra thimble of gasoline. Rev Match works fine where it is intended to work, for example, it does a great rev match as I slow my car at the end of VIR's back straight and I am downshifting from 5th to 3rd. As I approach the turn at speeds over 150 mph, I apply the brakes so I can carry at least 110 mph past the flagger at the kink at the end of the straight and I downshift from 5th to 4th, followed shortly after by the downshift to third while carrying the brake to slow down to about 50 mph to enter the turn at the top of the roller coaster.

Bill

 

Very impressive, Bill. My top speed in any of my Corvettes was 110. I wouldn’t even know what 150 feels like. Well, maybe I do. I had a passenger with me. Actually several as the Boeing 737 lifted off the runway.

 

The B737s I flew had a ground speed readout but of course the wing flies on indicated airspeed. One time during a heavy weight takeoff from Mexico City, we picked up a tailwind when we were above 150 kts IAS and it took forever to get the required airspeed for liftoff. I recall seeing a ground speed of about 205 kts, which is about 235 mph and definitely above tire limit speed. Yes, it felt like we were going really fast. The time I took our 'vette to 160+ mph felt even faster because you are sitting so low to the ground.

 

That is pretty bizarre when you consider how much a 737 weighs. As a passenger, I flew into Brazil a few times and the passengers always give a loud applause to the pilot when he lands smoothly.

 

Who tuned the car? Sounds like an issue with the tune.

 

While you have some great suggestions here, if it were my car I would go back into the MGW shifter and make sure the alignment is dead on. If it’s a bit off, I could see how it could think it’s going into a gate before it actually does and cause what you’re experiencing. After I installed my MGW, I needed to go back in because mine did not come with the alignment tool (I bought preowned) and it was not aligned exactly right. If you don’t have the alignment tool or didn’t get it with your car, you can order one from MGW for ~$20. Just give them a call or reach out to them via email. I’d do this before going down any other more in-depth or expensive rabbit holes.

 

When running with Stage 2 Aero I can hit 159 on the back straight, however, the car doesn't handle the uphill Esses as well, and the overall lap time is less. With the car set in track mode and a race alignment, the car feels solid on the ground at 159. Other than things getting a little more exciting in the braking zone, trying to scrub off the extra speed. One finger on the steering wheel would hold its direction, other than the fear of having a tire or other issue requiring both hands solidly on the wheel. That is what is nice about rev match, it makes for a quick downshift, so the hands are on the wheel a bit longer. Using it for 10 years has spoiled me since I have lost some of my ability to heel-toe downshift quickly.

Bill

 

I was doing rev match mechanically as a bus driver when I was in high school. I was assigned an old Chevy powered bus with a four speed transmission that had few, if any, synchronizers. My route had lots of very steep hills and I had to double clutch during every downshift:
1. Clutch in and shift to neutral.
2. Clutch out and rev the engine to increase the input shaft speed.
3. Clutch in to downshift, hopefully without grinding,
4. Clutch out

 

I just bought the tool, so I’ll keep the chain updated after it arrives.

 

A little different from the current heel/toe/rev match single-clutch method, which doesn't involve letting the clutch out to match the input shaft speed. The C7 transmission has synchronizers in the forward gears that help match transmission input shaft speed to engine speed. Since the transmission input shaft will speed up on a downshift, the key is to match the engine rev to the input shaft, which Rev Match is extremely good at doing, thus reducing the chances of locking up the rear wheels when braking hard into a corner and ending up doing donuts when the clutch is let out. Note the Black BMW in the video.


Rev Match can avoid the scare and the embarrassment.

Bill