CT4-V Blackwing Manual Transmission Engine Revving

[Dirkbg]

When I'm inching up at a traffic light, or inching up at a drive-through window line, I'll put the car in gear and slightly let out the clutch to take up the space in line. But when I take it out of gear and let off the clutch, and without touching the accelerator, the engine will give a quick rev to about 2000 rpm. It's kind of embarrassing because it seems like I'm showing off, even when it's in normal Tour mode. Do they all do that, or do I need to have it checked out? If it's normal, I wonder why it does it.

 

[Jameson's Viggen]

The one I had for Spring Mountain did it, mine doesn't.

 

[Tall Steve]

#A10, lol.....

 

[Blackwing16]

Do you have rev match on ever? I kinda remember my car doing this every once in a while and I think it might have something to do with the software in the car thinking you’re going down a gear. I’ve had it do it even with rev match off.

 

[LastGas]

Definitely not just you. Happens occasionally in my car too, rev match off. There's so much happening in the ecu between our foot and the throttle. I wonder if it is some anti-stall logic that isn't applied right? It happens for me most often after a fairly quick partial clutch release but then depressing the clutch again, like when you're trying to inch up a hill.

 

[Kanetch]

I have the same experience as LastGas

 

[Lithoss]

I'm not sure if mine does that exact behavior (I'll have to pay attention), but it does seem to rev up unexpectedly (ie, not when I'm down shifting) very briefly with now and then with rev matching on. Never without rev matching. I haven't quite figured out the pattern yet.

 

[JonnyLewser]

Sticky throttle issues

Happens to my 4BW MT6 every now and then (no rev match on).

 

[Vigster]

Sticky throttle issues

Happens to my 4BW MT6 every now and then (no rev match on).

I don't think it's sticky throttle. Mine will do this occasionally with nominal or no throttle input after the revs have settled. I think it is some sort of anti-stall/hill-assist function that is pre-programmed.

I would be curious to know what your mileage is and how warm the engine was? Mine seems to do it more frequently when I'm first setting off in the morning and the oil temp is only 100 degrees or so.

 

[JonnyLewser]

I don't think it's sticky throttle. Mine will do this occasionally with nominal or no throttle input after the revs have settled. I think it is some sort of anti-stall/hill-assist function that is pre-programmed.

I would be curious to know what your mileage is and how warm the engine was? Mine seems to do it more frequently when I'm first setting off in the morning and the oil temp is only 100 degrees or so.

I'm just shy of 6k, but it has happened sporadically since I've had the car. Usually happens when engine oil is 194ish

 

[Vigster]

I'm just shy of 6k, but it has happened sporadically since I've had the car. Usually happens when engine oil is 194ish

That's odd. My guess still stands that is is an anti-stall program. My 6MT SS would raise the revs automatically if I slipped the clutch without throttle in stop/go traffic. Although with like 250+ lb/ft of torque at 1200rpm it would roll regardless lol

 

[shbox]

Maybe some analyzation with Pi Toolbox would be helpful (if equipped with PDR) or a scan data log.

 

[WONT TAP]

This is Auto Rev Matching doing it's job. The ECM is trying to anticipate your next gear selection, and bringing engine speed up accordingly. Disable Rev Match and things will be much more 'normal'.

 

[Vigster]

This is Auto Rev Matching doing it's job. The ECM is trying to anticipate your next gear selection, and bringing engine speed up accordingly. Disable Rev Match and things will be much more 'normal'.

I never use Rev-Match and the car does this auto-blipping (never higher than like 1800-2k rpm) only when stopped, in first gear, and slipping the clutch with little or no throttle. Usually when I'm trying to inch forward but feel revving is unnecessary the card does it on its own.

 

[kamome97]

It happens to me sometimes, regardless of rev match on or off. Not sure why but I haven't bothered to look into it much as it's not too much of a problem (...yet)

 

[Dirkbg]

Mine is 1400 miles, it's warm when it happens, no rev matching (well, I've never used rev matching so I assume it's off). It doesn't make sense it's an anti-stall measure, because it revs in neutral letting off the clutch, not touching the accelerator. So, there isn't any drive line load to stall it, but maybe it assumes I'm in gear? It should be smart enough to know if it's in a gear or neutral. It also seems odd some experience it and others don't.

 

[pmsteinm]

My 2009 M6 V does this sometimes as well. I know I read text in the service manual how it holds revs in neutral to burn off various pollutants at certain RPMs/loads/etc. I wonder if its something related to that? The 09 doesn't have rev match so it obviously isn't related to that in my case.

It happens so rarely I don't think much about it. I'll have to pay more attention to what I'm doing when it happens.

 

[jbawden]

I was going to post emission related as @pmsteinm suggests. Maybe the work around is a little throttle even though none is really required to creep forward...or don't eat from a drive-thru!

 

[ClassaxV]

Per the manual, auto rev match for downshifts is only enabled by the switch, auto rev match for upshifts AND no lift shifting are constantly on and happen if the right conditions are met.

There definitely is some sort of anti-stall programing in 1st from a stop. It took me forever to get used to when it would or would not try and help me from a stop. If you slowly let out the clutch it will rev and not stall, and this can be done fairly quickly, however, if you add any accelerator whatsoever, it assumes you have full control and you have to do your own throttle application to keep from stalling.

Same with the hill start and stop /hold if you come to a complete stop on a hill the brakes normally hold for a couple of seconds when released, but if you slow to slowly, or the car doesn't detect the grade then it will roll.

The car is thinking for itself and at time that has resulted in a few tense HAL moments.

 

[Dirkbg]

I think I can understand that logic. But in my case I'm not in gear when I disengage the clutch because I just give it a little push in first gear feathering the clutch, then shift out of gear and let off the clutch, and then it gives a quick blip of 2000 rpm. There shouldn't be any reason to rev at that point since it's not in gear, and it should detect that. I've never noticed any revving going on when I'm shifting into gear from a stop.