[2020m2c]

2k miles on the car. I was a rev match skeptic but I guess I've gotten too used to it.

However, twice in one drive today I locked the rear end when down shifting 3rd to 2nd. Rev match mysteriously quit. Like squealed the tires and violently quit. Surprised the crap out of me the first time it did it and I looked like an ass to the 300zx following me. Second time I was alone but just as surprising.

It did not happen sequentially but randomly and only twice on a 15mile trip. I always drive sport+/sport+ with MDM. Both my M buttons are programmed that way. Never drive it any other way. I've never had this happen before and I've gotten pretty comfortable with the car, even spent a bit of time on the track with it. Anyone else have this issue?

[robertm]

I always drive with traction control fully off unless it's raining so not much experience with it. You obviously didn't have TC fully off though or it would have happened repeatedly.

I've not heard of anyone having this issue before but I'm sure others will chime in. I can definitely see how that would suck if your expecting the car to do the rev matching for you.

[Thescout13]

I'm not saying this is what caused it, but hear me out as a potential reason:

Auto-rev match can be overridden by heel-toe downshifting. That is, if you go for a downshift and heel toe it (either out of habit or by accident) prior to entering the gate sensor (which causes the auto rev match) the car will cancel the auto rev match and let you do the heel toe.

That said, and this has happened to me, if you happen to be braking while downshifting and you have big ass clown feet (like I do) and accidentally tap the throttle (especially in sport + where the throttle is super sensitive) but didn't tap it enough to do an accurate heel toe downshift, but enough for the car to think you are trying to rev match yourself and cancel the auto-rev match, the car will down shift hard as hell (and even lock up).

Essentially, if you accidentally disengaged the auto rev match by tapping the throttle while braking and downshifting, the car will not rev match fully into the lower gear and it feels as if you were downshifting without rev matching (and crappy heel toe technique).

Another potential reason could be that you went ahead and down shifted (especially 3-2) on the shifter but forgot to release the clutch (sometimes can happen while your simultaneously breaking) and let the revs get to low before you released it, it could cause the same feeling.

[Moflow]

Originally Posted by Thescout13

I'm not saying this is what caused it, but hear me out as a potential reason:

Auto-rev match can be overridden by heel-toe downshifting. That is, if you go for a downshift and heel toe it (either out of habit or by accident) prior to entering the gate sensor (which causes the auto rev match) the car will cancel the auto rev match and let you do the heel toe.

That said, and this has happened to me, if you happen to be braking while downshifting and you have big ass clown feet (like I do) and accidentally tap the throttle (especially in sport + where the throttle is super sensitive) but didn't tap it enough to do an accurate heel toe downshift, but enough for the car to think you are trying to rev match yourself and cancel the auto-rev match, the car will down shift hard as hell (and even lock up).

Essentially, if you accidentally disengaged the auto rev match by tapping the throttle while braking and downshifting, the car will not rev match fully into the lower gear and it feels as if you were downshifting without rev matching (and crappy heel toe technique).

Another potential reason could be that you went ahead and down shifted (especially 3-2) on the shifter but forgot to release the clutch (sometimes can happen while your simultaneously breaking) and let the revs get to low before you released it, it could cause the same feeling.

Interesting, this has NOT been my experience, however i'm generally double clutching with my rev-matches so perhaps that's confusing the car.

I'll shift out of third, into neutral, release the clutch, rev the engine and then go for second gear only to have the computer be like "Hey bro, that wasn't a big enough throttle blip, let me help you out"

That said, I think it doesn't rev match if you take too long. Like when i'm coming to a stop at a stop light, the car usually doesn't rev match going into first (not a habit, just tried it a few times out of curiousity.) In that case i'm usually sitting in neutral for a few seconds before trying first at which point the car will not rev match.

I sort of wonder if the OP was cruising, dropped it into neutral, hung out there for a few seconds and THEN went to drop a gear.

[hAxel]

Originally Posted by Thescout13

you have big ass clown feet

I don't think any other bimmerpost post has been so relevant to me

[ROBM2C]

Happened to me once , I was in mdm sport +....came in aggressive in a roundabout - downshift from 3-2 and back end kicked out pretty hard .

[2020m2c]

Originally Posted by Thescout13

I'm not saying this is what caused it, but hear me out as a potential reason:

Auto-rev match can be overridden by heel-toe downshifting. That is, if you go for a downshift and heel toe it (either out of habit or by accident) prior to entering the gate sensor (which causes the auto rev match) the car will cancel the auto rev match and let you do the heel toe.

That said, and this has happened to me, if you happen to be braking while downshifting and you have big ass clown feet (like I do) and accidentally tap the throttle (especially in sport + where the throttle is super sensitive) but didn't tap it enough to do an accurate heel toe downshift, but enough for the car to think you are trying to rev match yourself and cancel the auto-rev match, the car will down shift hard as hell (and even lock up).
.

100% could have been a clown foot issue. Although I was wearing same shoes as per normal, they are quite large haha.

Originally Posted by hAxel

I don't think any other bimmerpost post has been so relevant to me

Same haha

Strange that it only was 2nd to 3rd both times on separate stretches of road — once while coming to a stop light and once while turning a corner.

Well, for what it's worth several hours later I drove back the same route without incident. Hope it never happens going 5th to 4th at speed on an exit ramp

[hAxel]

Originally Posted by 2020m2c

100% could have been a clown foot issue. Although I was wearing same shoes as per normal, they are quite large haha.



Same haha

Strange that it only was 2nd to 3rd both times on separate stretches of road — once while coming to a stop light and once while turning a corner.

Well, for what it's worth several hours later I drove back the same route without incident. Hope it never happens going 5th to 4th at speed on an exit ramp

I haven't had the issue myself, but I do have the clown shoes (15 4E)

[clutchdj]

figures, car must hate the software

[tokki]

Why are you double clutching? For sure this is the reason. Just downshift normally ya goof.

[Moflow]

Originally Posted by tokki

Why are you double clutching? For sure this is the reason. Just downshift normally ya goof.

It’s fun and habit. It’s technically the best for wear and tear though really, in the real world I doubt that’s the case. So yeah. Just for fun!

I’ll have to rewire my brain a bit to quit doing it, but if the car really does cancel the auto rev-match it’s worth it.

Speaking of which, another minor (1st world) problem I have is that the various throttle modes make blips inconsistent. A smaller blip is need to rev match in sport plus than in eco mode.

Eco mode reminds me just a tiny bit of my old 80s celica, old-school turbocharging meant that my 4-3 downshift blip was accomplished by putting my foot down TO THE FLOOR for like a quarter of a second. Then, bam! Perfect rev match with zero resistance going into gear. I could even do it without using the clutch at all if I was feeling brave/risky.