Pa Joe

Help please! I have a 2016 Z06 manual. When in rev-matching mode, I believe there should be "one blip" when downshifting. Mine, however, many times will blip twice, especially at lower RPM, around 2000 RPM. The "blip--blip" just sounds weird, and my friends have noticed it too. Higher RPM around 4000, it mostly blips properly. Sometimes it blips when you take it out of gear putting it in neutral to coast for a few seconds, then blips again when put in gear. Why would it blip sometimes when going to neutral before engaging in lower gear? Dealerships that I talked to don't seem to have a clue, even one of the largest dealers in Columbus, Ohio area. I even found Tadge Jeuchter on LinkedIn and asked for guidance to someone knowledgeable! Has anyone experienced a similar issue on any manual C7? I would even drive to Bowling Green to have it looked at!!

Bill Dearborn

I guess the real question is So What? Two blips or one as long as it blips as needed who cares?

Bill

Pineapple

You might be shifting too slow. The sensor is in the transmission and it detects minuscule movements and it actually uses a bit of “predictive” algorithm to predict which gear your mostly shifting into. If you pause slightly in neutral the 1st blip is probably for the gear the tranny thinks you’re shifting into, the second blip is for the actual gear your shifting to.

*disclaimer, the above information may be based open actual data or it could be completely made up to sound accurate and most importantly intelligent.

X25

Sounds about right. When you get closer to different shift gates, it revs accordingly. Nothing is wrong with the car.

badhabit_wb

Mine will do that if I shift slow or don't shift to the next lower gear, like if I go from 4th to 2nd.

davidtcpa

Mine does that too.

I don't think the rev match was designed to be driven slowly at low RPM's. I did not like using it when coming to a stop because I sounded like a douche when it revved while slowing down IMO. For street driving, I only use it in higher RPM situations.

Widgeon5

[QUOTE= Sometimes it blips when you take it out of gear putting it in neutral to coast for a few seconds, [/QUOTE]

I have found that holding just a little rightward pressure (holding it in the 3-4 gate) when you go to neutral will stop this. If you just relax the lever into neutral it can spring a little toward the 1-2 gate and fool the rev match.

JerryU

Been using rev match since I got my C7 Z51 in October 2013. Love it, use it 99% of the time. I don't get a double blip.

However had to break some old habits. There are Hall sensors that detect where the level is even when it's moved in the neutral gate. A common downshift for me is when in town or even on our rural roads around here I am usually in 5th. I shift directly to 3rd for a turn. With my C6 and prior cars when the clutch was disengaged I would put the shift level in the skipped gear helping the synchros by spooling up a cluster gear. Can't do that with rev match, it confuses the computer that is trying to predict what you plan to do! The M7 has triple synchros, let them do the work!

Another good example is folks who complained about it over-revving. Was able to duplicate that on a low speed 5th to 3rd downshift by moving the shift handle slightly toward the 1st/2nd gate. Never went into those gears but the engine revved as if I was going to 2nd. Have to be very careful where you put the lever. I also agree with the comment you need to shift fairly quickly.

I find it very useful around town and on the Interstate when in 7th I shift directly to 4th for an exit ramp bypassing the other two overdrives, 6th and 5th. Perfectly smooth transition for that ~1500 to ~3000 rpm shift. In fact, I find it most useful when NOT driving in anger! Been driving standard shifts for ~60 years as my DD. Quite good at heel-toe in a one gear change downshift when the car will be at a high rpm. However modulating the throttle to go from 1500 rpm to 3000 rpm and get a perfect rev match is more difficult. In my C6 got it perfect half the time! Coming off the highway to the rural street where I live would always heel-toe even with my modified 5 speed S10. Bad pedal placement made a perfect match less than 50% at lower rpms where at high rpms it was fine!

However rev match does it perfectly every time. One other note, be sure your foot is fully off the throttle pedal.

PS: A good example of the need to shift quickly is rev match on upshifts! Frankly never felt it was doing anything until I purposely shifted slow! As most, when upshifting my foot is off the throttle and the engine slows naturally. Rev match does nothing different. However IF you shift slow and the revs would go lower than a perfect match it will hold the proper revs for about 2 seconds-no longer. I never shift that slow!

badhabit_wb

I'll add to that. When driving in anger it will also let you know if you're trying to shift to the wrong gear. That's a good thing. Rev match won't over rev the engine but it will let you know if you're going to put it in a gear that will cause an over rev. I always use it on track now.

JerryU

^^

Recall a pro driver testing a Z06 who said he uses it as well since he’s sure being slightly off a perfect match will not upset his car so pushes to the limit and can focus on hitting his braking points.

I’m reminded of watching a race at Mid Ohio years ago where Brian Redman hit his braking spot in a tight turn where I was standing. He hit it within inches lap after lap while some of the other “pros” were close but not like him! Probably why he won the race!

The sound may give a warning but rev match can't stop you from putting a manual shift into a gear that will over-rev the engine when the clutch is engaged. The rev limiter will shut off the engine but the speed and momentum can still over-spin the engine. With an automatic it can stop to low a selected gear from engaging.

crapthatsloud

Those are all things that a human might do when driving a manual trans and they all seem to serve a purpose. Slowing down from a stop, if I'm coasting in neutral and need a gear I will almost always give whatever car I'm driving a little bit of throttle to help it slide into gear. The rev-match feature seems to be mostly optimized for slam-shifts and fast driving.

JerryU

Absolutely the opposite, IMO! I'm very good at heel-toe for "slam-shift-fast driving" as you refer to it! Not hard to learn to stab the throttle and get a perfect match as the single lower gear you're downshifting to is near redline!

Much harder to modulate the throttle to get a perfect match say when cruising at say 45 mph in 5th gear (~1400 rpm) when making a turn and wanting to be in 3rd gear (~2800 rpm) and get a perfect match! I do that in most turns while causally shifting and rev match makes it perfect every time.

Same on the interstate when in 7th gear at 70 mph (~1450 rpm) and going on to an exit ramp where 4th gear may be where you want to be. Using two other overdrives, 6th and 5th, to get there is a waste of time so I go directly to 4th (~3000 rpm.) Rev match makes that casual shift easy and a perfect match.

One thing you cannot do that I had to unlearn was putting the shift level anywhere accept where you intend to shift. I'll explain. In my C6 I would also shift from 5th to 3rd when making a turn. However an old habit was "while the clutch was depressed" I would put the shift lever in 4th then 3rd before I engaged the clutch. Spools up the cluster gear! Confuses the computer that is anticipating your intensions.

Perhaps a better example is folks who say it overrevs. I was able to duplicate that in a test! On my normal casual 5th to 3rd downshift while driving at ~45 mph I pulled the shift level just slightly toward the 1st/2nd gate BUT while still in neutral. The computer anticipated I was going to shift to 2nd even through I was in the neutral gate. So instead of holding at ~2800 rpm it jumped to ~4000! There are Hall sensors that monitor the shift level movement even in neutral.

Bottom Line, you can only put the shift lever where you want to go! Can't rattle it in neutral to be sure that is where you are!

falconhulk

The car trys to predict your behavior. If you hesitate in neutral, you would expect an additional blip before going into gear...unless you already dropped too the correct rpm through breaking. It's doing exactly what it was designed to do.

Skid Row Joe

In English please? !

Skid Row Joe

Exactly correct!