7 Speed Manual Auto Rev Matching Issue
04-26-2018, 08:20 PM
#1
4th Gear
Thread Starter
Join Date: Apr 2018
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
7 Speed Manual Auto Rev Matching Issue
I'm not getting much help from Porsche on this apparent issue I've found, so I'm wondering if anyone has experienced the same thing or if my car is acting up.
On the 991.2 C2, the manual transmission auto rev-match is supposed to rev match when downshifting in sport or sport + modes, but there are 2 separate behaviors of the system that seem odd to me:
1) Every auto blip falls short of the required RPM by about 50-100 rpm. This happens for almost every single downshift, no matter what gear i'm downshifting into. I know this is happening because the second I take my foot off the clutch, the car lurches a little because the blip is not perfectly matching what the RPM should be at that speed. It's a minor discrepancy, but I don't understand why the blip is not perfect. I owned an M4 before this, and that auto blip nailed the correct RPM every single time.
2) This is where the auto rev match really seems to fail, and it only happens when downshifting into 2nd gear from either 5th, 6th, or 7th gear. If I'm going at a speed (50mph) where the car needs 5000 RPM in 2nd gear, and downshift from 5th, 6th, or 7th gear to 2nd, the engine will only spin up to about 4500 RPM or less. It rarely ever spins up to nearly the correct RPM, and i'm forced to let the clutch slip to engage smoothly. Downshifting into 3rd gear or even 1st gear doesn't have this same issue (except for the constant miss of 100 rpm that I mentioned above). It really is only 2nd gear where the auto rev match feature just completely misses the mark, making it all the stranger.
Hoping someone has either experienced these same behaviors, meaning that Porsche's coding is poor, or that they have never had these issues, meaning that something is wrong with my car alone. Thanks!
On the 991.2 C2, the manual transmission auto rev-match is supposed to rev match when downshifting in sport or sport + modes, but there are 2 separate behaviors of the system that seem odd to me:
1) Every auto blip falls short of the required RPM by about 50-100 rpm. This happens for almost every single downshift, no matter what gear i'm downshifting into. I know this is happening because the second I take my foot off the clutch, the car lurches a little because the blip is not perfectly matching what the RPM should be at that speed. It's a minor discrepancy, but I don't understand why the blip is not perfect. I owned an M4 before this, and that auto blip nailed the correct RPM every single time.
2) This is where the auto rev match really seems to fail, and it only happens when downshifting into 2nd gear from either 5th, 6th, or 7th gear. If I'm going at a speed (50mph) where the car needs 5000 RPM in 2nd gear, and downshift from 5th, 6th, or 7th gear to 2nd, the engine will only spin up to about 4500 RPM or less. It rarely ever spins up to nearly the correct RPM, and i'm forced to let the clutch slip to engage smoothly. Downshifting into 3rd gear or even 1st gear doesn't have this same issue (except for the constant miss of 100 rpm that I mentioned above). It really is only 2nd gear where the auto rev match feature just completely misses the mark, making it all the stranger.
Hoping someone has either experienced these same behaviors, meaning that Porsche's coding is poor, or that they have never had these issues, meaning that something is wrong with my car alone. Thanks!
04-26-2018, 10:41 PM
#2
Burning Brakes
So here's a question.....are you going from 5, 6, and 7th directly to 2nd or are you gating your way down? If you are going directly from these gears maybe the software is protecting what it perceives as a "money shift" situation. Not sure any other scenario makes sense. I've made it a practice to at least gate my way down to the gear I want. Not sure if this is your issue......just food for thought........Phil
04-26-2018, 11:59 PM
#3
Race Car
Join Date: Oct 2002
Location: Fairfax County, Virginia
Posts: 4,025
Received 3,879 Likes
on
1,359 Posts
It only rev-matches in Sport Plus. Not sure how you can determine a 50 to 100 rpm variance, that's a mighty small variation. Why are you expecting rev matching from 7 - 6 - 5 to 2nd gear? That's not how you drive a manual transmission properly. 7th is an overdrive gear only - for highway cruising. if you are downshifting at speed from 6th to 2nd you best thank your lucky stars you haven't done a money-shift and grenaded the engine (hint: that will not be a warranty item). I'm sorry, but this is not the car's fault - its operator error. Get thee to a Driver's School with a good Instructor and you will be shown how to heel and toe through the gears correctly. That Auto-blip is the goofiest, most stupid feature on my Porsche - I detest it and don't use Sport Plus for that reason. The Art of Shifting means you heel and toe matching your rev-shifts as you come down through the gearbox one gear at a time, not rely on some computer to make you feel like Steve McQueen.
The second goofiest feature on a 991 is the over-run burbling of the exhaust they designed into the engine management software. I know, I know, it makes you feel like you're at 24 hours of Daytona, but that's done for marketing purposes to sell the car to wannabe racers and I'd rather not have that on my car, either.
The second goofiest feature on a 991 is the over-run burbling of the exhaust they designed into the engine management software. I know, I know, it makes you feel like you're at 24 hours of Daytona, but that's done for marketing purposes to sell the car to wannabe racers and I'd rather not have that on my car, either.
04-27-2018, 08:27 AM
#4
Rennlist Member
Can't say I have noticed any lurching or any untoward behavior of the transmission when I downshift while driving in sport mode in my C4S. OTOH, I wouldn't be able to tell small differences in rpm either.
My downshifts, when I am skipping gears, typically will involve sixth to fourth (say when I am exiting a highway) and then further down to third. Or I will do an occasional fifth to third downshift when the speed limit on a backroad suddenly drops from 50-55 to 35. Transmision behaves flawlessly. Anyway, the car has so much torque that I can leave it fourth from speeds of 35-55 mph and not bother downshifitng at all. The only reason I find to downshift to second is when I almost coming to a stop behind a car.
My downshifts, when I am skipping gears, typically will involve sixth to fourth (say when I am exiting a highway) and then further down to third. Or I will do an occasional fifth to third downshift when the speed limit on a backroad suddenly drops from 50-55 to 35. Transmision behaves flawlessly. Anyway, the car has so much torque that I can leave it fourth from speeds of 35-55 mph and not bother downshifitng at all. The only reason I find to downshift to second is when I almost coming to a stop behind a car.
04-27-2018, 08:30 AM
#5
Rennlist Member
I love the auto-rev match function. Never been heel/toe guy and I'm secure in that. I would suggest to try not to downshift three or more gears. The car is amazing, but I would row down through to 2nd, or wait a bit before making the shift. I use sport plus on my 991.1 all the time and haven't experienced an issue like this. Try downshifting fewer gears and see if that fixes the problem. The auto-rev match will not stop you from doing a money downshift. Good luck and let us know what you find.
04-27-2018, 09:01 AM
#6
I'm wondering whether the OP is simply too slow with the clutch. The car will rev-match but it won't hold it there forever. If you don't let the clutch out quickly the revs will start to drop naturally.
I'm mediocre and getting better at heel-toe and will keep practicing but I DO love the rev-match feature.
My Boxster GTS did it perfectly and for any gear that was available. My GT3 does as well, though it's a little different in ways I haven't been able to describe properly yet. It might just be the different sound.
It won't try to rev-match a money-shift. If you're going too fast for the gear you've selected, it simply won't try. That's your warning not to let out the clutch. That said... if you're not going too fast, you can pick any gear you want. Come out of 6th and want to go to 2nd? Go for it. It rev-matches perfectly. Pull out of 6th and want to go to 4th and then change your mind and want 3rd? When you push the stick to 4th it rev-matches perfectly. Even if you don't let the clutch out, if you move the stick to 3rd or to 2nd or back to 5th it will rev-match perfectly every single time.
Did you wait too long to let the clutch out and now the revs have dropped a bit? Move the stick to neutral and back the gear you want. It'll rev-match again.
It's a good system. I expect the OP isn't using it right.
I'm mediocre and getting better at heel-toe and will keep practicing but I DO love the rev-match feature.
My Boxster GTS did it perfectly and for any gear that was available. My GT3 does as well, though it's a little different in ways I haven't been able to describe properly yet. It might just be the different sound.
It won't try to rev-match a money-shift. If you're going too fast for the gear you've selected, it simply won't try. That's your warning not to let out the clutch. That said... if you're not going too fast, you can pick any gear you want. Come out of 6th and want to go to 2nd? Go for it. It rev-matches perfectly. Pull out of 6th and want to go to 4th and then change your mind and want 3rd? When you push the stick to 4th it rev-matches perfectly. Even if you don't let the clutch out, if you move the stick to 3rd or to 2nd or back to 5th it will rev-match perfectly every single time.
Did you wait too long to let the clutch out and now the revs have dropped a bit? Move the stick to neutral and back the gear you want. It'll rev-match again.
It's a good system. I expect the OP isn't using it right.
04-27-2018, 09:10 AM
#7
Banned
Join Date: Jan 2013
Location: Chicagoland Area
Posts: 26,142
Likes: 0
Received 5,388 Likes
on
2,509 Posts
I down shift often. But I always gate my way down in each gear. All the posters before me have already given you great insight.
Trending Topics
04-27-2018, 10:34 AM
#8
Rennlist Member
Same here. When I learned to heel-toe, I could never figure out how much gas to goose if I skipped a gear. I like the rev matching feature, use it all the time, and it hasn't been an issue.
04-27-2018, 11:00 AM
#9
Three Wheelin'
I've heel/toe/matched revs since I was 16 (some double clutching in the 914 back then too) and love it. Auto matching would be like PDK to me. Only time you would go down more than 1 gear at a time would be racing into a sharp corner at speed I would think. OP, try turning it off and matching revs yourself....its great fun.
04-27-2018, 12:47 PM
#10
4th Gear
Thread Starter
Join Date: Apr 2018
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Appreciate the feedback everyone, let me clear up a few things:
- I wish it was, but this isn't operator error. I've driven a manual since I was 15, and owned an M4 before this that did rev-matching perfectly for any gear, any situation. The Porsche dealership shop foreman noticed the same behavior with my car, but didn't know if all the manual 911s acted like that or not. He is following up with the technical team, but not sure when he will get an answer. That's why I decided to ask the community here, so thanks for those who actually responded in a helpful way.
- I'm not shifting into 2nd gear at a speed where it would over-rev the engine, so no the computer is not trying to "protect" anything. If it works going into 1st gear (of course I wouldn't normally shift from 5-6th into 1st except for the sake of testing), there's no reason why it wouldn't work going into 2nd.
- Shifting into 2nd gear from a high gear is really only a benefit for engine braking, which I do a lot when coming up suddenly to a red light. Sure I could drop a gear in between if I had time, but the point is that there's no reason for the car not to rev match correctly into 2nd gear anyways.
- I looked at my tachometer again when auto rev-matching and it's actually missing every rev-match by ~200 rpm, not 50-100 like I said before. Either way, it's noticeably off. This is the more annoying issue because I can't solve it by just gating down more often.
- No i'm not holding in the clutch too long. I'm putting the clutch in, changing the gear, and immediately taking it off, within 1 second.
- I know everyone who heel-toes loves to say it's the right way to drive and it's more fun, but some people like the auto rev-match. Manual drivers need to stick together cuz there's already too few of us left. Stop hatin'!
- I wish it was, but this isn't operator error. I've driven a manual since I was 15, and owned an M4 before this that did rev-matching perfectly for any gear, any situation. The Porsche dealership shop foreman noticed the same behavior with my car, but didn't know if all the manual 911s acted like that or not. He is following up with the technical team, but not sure when he will get an answer. That's why I decided to ask the community here, so thanks for those who actually responded in a helpful way.
- I'm not shifting into 2nd gear at a speed where it would over-rev the engine, so no the computer is not trying to "protect" anything. If it works going into 1st gear (of course I wouldn't normally shift from 5-6th into 1st except for the sake of testing), there's no reason why it wouldn't work going into 2nd.
- Shifting into 2nd gear from a high gear is really only a benefit for engine braking, which I do a lot when coming up suddenly to a red light. Sure I could drop a gear in between if I had time, but the point is that there's no reason for the car not to rev match correctly into 2nd gear anyways.
- I looked at my tachometer again when auto rev-matching and it's actually missing every rev-match by ~200 rpm, not 50-100 like I said before. Either way, it's noticeably off. This is the more annoying issue because I can't solve it by just gating down more often.
- No i'm not holding in the clutch too long. I'm putting the clutch in, changing the gear, and immediately taking it off, within 1 second.
- I know everyone who heel-toes loves to say it's the right way to drive and it's more fun, but some people like the auto rev-match. Manual drivers need to stick together cuz there's already too few of us left. Stop hatin'!
04-27-2018, 12:56 PM
#11
4th Gear
Thread Starter
Join Date: Apr 2018
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
I'm wondering whether the OP is simply too slow with the clutch. The car will rev-match but it won't hold it there forever. If you don't let the clutch out quickly the revs will start to drop naturally.
I'm mediocre and getting better at heel-toe and will keep practicing but I DO love the rev-match feature.
My Boxster GTS did it perfectly and for any gear that was available. My GT3 does as well, though it's a little different in ways I haven't been able to describe properly yet. It might just be the different sound.
It won't try to rev-match a money-shift. If you're going too fast for the gear you've selected, it simply won't try. That's your warning not to let out the clutch. That said... if you're not going too fast, you can pick any gear you want. Come out of 6th and want to go to 2nd? Go for it. It rev-matches perfectly. Pull out of 6th and want to go to 4th and then change your mind and want 3rd? When you push the stick to 4th it rev-matches perfectly. Even if you don't let the clutch out, if you move the stick to 3rd or to 2nd or back to 5th it will rev-match perfectly every single time.
Did you wait too long to let the clutch out and now the revs have dropped a bit? Move the stick to neutral and back the gear you want. It'll rev-match again.
It's a good system. I expect the OP isn't using it right.
I'm mediocre and getting better at heel-toe and will keep practicing but I DO love the rev-match feature.
My Boxster GTS did it perfectly and for any gear that was available. My GT3 does as well, though it's a little different in ways I haven't been able to describe properly yet. It might just be the different sound.
It won't try to rev-match a money-shift. If you're going too fast for the gear you've selected, it simply won't try. That's your warning not to let out the clutch. That said... if you're not going too fast, you can pick any gear you want. Come out of 6th and want to go to 2nd? Go for it. It rev-matches perfectly. Pull out of 6th and want to go to 4th and then change your mind and want 3rd? When you push the stick to 4th it rev-matches perfectly. Even if you don't let the clutch out, if you move the stick to 3rd or to 2nd or back to 5th it will rev-match perfectly every single time.
Did you wait too long to let the clutch out and now the revs have dropped a bit? Move the stick to neutral and back the gear you want. It'll rev-match again.
It's a good system. I expect the OP isn't using it right.
04-27-2018, 01:46 PM
#12
Obviously don't do this all the time but, try slamming it into the gear and letting the clutch out immediately and with conviction. Think sequential manual as far as speed of the downshift goes and see if it's a hand-foot syncopation issue.
04-27-2018, 02:20 PM
#13
Three Wheelin'
Obviously a situation for the dealer.
No hate here, just dont see the difference between PDK and auto rev match MT. Just my opinion. Also not a wannabe 24 Hr racer but do love my sport exhaust burbles. Does that make me a bad person drcollie?
No hate here, just dont see the difference between PDK and auto rev match MT. Just my opinion. Also not a wannabe 24 Hr racer but do love my sport exhaust burbles. Does that make me a bad person drcollie?
04-27-2018, 07:39 PM
#14
Rennlist Member
Appreciate the feedback everyone, let me clear up a few things:
- I wish it was, but this isn't operator error. I've driven a manual since I was 15, and owned an M4 before this that did rev-matching perfectly for any gear, any situation. The Porsche dealership shop foreman noticed the same behavior with my car, but didn't know if all the manual 911s acted like that or not. He is following up with the technical team, but not sure when he will get an answer. That's why I decided to ask the community here, so thanks for those who actually responded in a helpful way.
- I'm not shifting into 2nd gear at a speed where it would over-rev the engine, so no the computer is not trying to "protect" anything. If it works going into 1st gear (of course I wouldn't normally shift from 5-6th into 1st except for the sake of testing), there's no reason why it wouldn't work going into 2nd.
- Shifting into 2nd gear from a high gear is really only a benefit for engine braking, which I do a lot when coming up suddenly to a red light. Sure I could drop a gear in between if I had time, but the point is that there's no reason for the car not to rev match correctly into 2nd gear anyways.
- I looked at my tachometer again when auto rev-matching and it's actually missing every rev-match by ~200 rpm, not 50-100 like I said before. Either way, it's noticeably off. This is the more annoying issue because I can't solve it by just gating down more often.
- No i'm not holding in the clutch too long. I'm putting the clutch in, changing the gear, and immediately taking it off, within 1 second.
- I know everyone who heel-toes loves to say it's the right way to drive and it's more fun, but some people like the auto rev-match. Manual drivers need to stick together cuz there's already too few of us left. Stop hatin'!
- I wish it was, but this isn't operator error. I've driven a manual since I was 15, and owned an M4 before this that did rev-matching perfectly for any gear, any situation. The Porsche dealership shop foreman noticed the same behavior with my car, but didn't know if all the manual 911s acted like that or not. He is following up with the technical team, but not sure when he will get an answer. That's why I decided to ask the community here, so thanks for those who actually responded in a helpful way.
- I'm not shifting into 2nd gear at a speed where it would over-rev the engine, so no the computer is not trying to "protect" anything. If it works going into 1st gear (of course I wouldn't normally shift from 5-6th into 1st except for the sake of testing), there's no reason why it wouldn't work going into 2nd.
- Shifting into 2nd gear from a high gear is really only a benefit for engine braking, which I do a lot when coming up suddenly to a red light. Sure I could drop a gear in between if I had time, but the point is that there's no reason for the car not to rev match correctly into 2nd gear anyways.
- I looked at my tachometer again when auto rev-matching and it's actually missing every rev-match by ~200 rpm, not 50-100 like I said before. Either way, it's noticeably off. This is the more annoying issue because I can't solve it by just gating down more often.
- No i'm not holding in the clutch too long. I'm putting the clutch in, changing the gear, and immediately taking it off, within 1 second.
- I know everyone who heel-toes loves to say it's the right way to drive and it's more fun, but some people like the auto rev-match. Manual drivers need to stick together cuz there's already too few of us left. Stop hatin'!
Porsche equips their cars with very good brakes. Good to use them. But your car. You know best how to use it.
04-27-2018, 07:53 PM
#15
Rennlist Member
Not sure I'd ever want to train my limbs to execute a downshift to 2nd from anything other than 3rd (or maybe, very occasionally 4th when it literally doesn't matter). I just wouldn't want that muscle memory, but YMMV.
As for engine braking, fine when backing off in gear, but skipping down multiple gears at a time and letting the clutch out to slow the car in a big way would worry me. Maybe the OP is doing it in a way that isn't detrimental. But, if real slowing power is required, a wise man told a teenage me to use the brakes. "Pads and rotors are cheaper than a new transmission," he said....even if PCCB may have altered that conventional wisdom.
As for engine braking, fine when backing off in gear, but skipping down multiple gears at a time and letting the clutch out to slow the car in a big way would worry me. Maybe the OP is doing it in a way that isn't detrimental. But, if real slowing power is required, a wise man told a teenage me to use the brakes. "Pads and rotors are cheaper than a new transmission," he said....even if PCCB may have altered that conventional wisdom.