Disabling the Rev Match feature

[speedo]

So I guess it can't be disabled on 2019 automatics. Thanks....That's all I needed to know but it would've been nice if they added the feature. Now everytime I slow down the engine revs and it attracts alot of attention in sport mode or track. Being that I have headers its cool but not so nice when a cop is sitting at a light or nearby.

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[Vlad Soare]

but not so nice when a cop is sitting at a light or nearby.

And if he is sitting nearby, what? What can he do? Tell your mother? Give you a ticket for revving the engine? Since when is that illegal?

 

[speedo]

And if he is sitting nearby, what? What can he do? Tell your mother? Give you a ticket for revving the engine? Since when is that illegal?

Unfotunately where i live in Houston they could give you a ticket for aggressive acceleration \ noise if they want. It also depends the the law officer to.

 

[Sivi70980]

Unfotunately where i live in Houston they could give you a ticket for aggressive acceleration \ noise if they want. It also depends the the law officer to.

Yeah sometimes they like to go crazy with noise laws. Something like can’t be heard 75 feet away or something dumb. Factory setup fails already so...

 

[Vlad Soare]

Over here I couldn't care less if a cop liked my exhaust sound or not. As long as the car is road legal and has the factory setup, there's nothing he or anyone else can do about it. And if he does, then I will have the ticket voided in a court of law, and then I will press charges against him for abuse of power - which is a criminal offence. But this is just theory, because in practice no policeman would do that. Besides, most of them are really nice and would be happy to hear what a real engine sounds like. We don't get to see too many V8s around here, and cops are as passionate about cars as anyone else. They would probably give me a thumbs up.

Anyway, coming back to our topic, what happens with an automatic gearbox isn't exactly 'rev matching' per se. It's just the intrinsic effect of shifting into a lower gear - i.e. the engine jumping to higher rpm. There's no way around that. When you downshift, the engine is bound to rev higher. All you can do is drive in Normal mode in D, so that it stays in higher gears longer.

 

[kodioneill]

In NY they can ticket you for no front plate. Ask me how I know after a 200 dollar fine.

 

[Norm Peterson]

Anyway, coming back to our topic, what happens with an automatic gearbox isn't exactly 'rev matching' per se. It's just the intrinsic effect of shifting into a lower gear - i.e. the engine jumping to higher rpm. There's no way around that. When you downshift, the engine is bound to rev higher.

I think we need to distinguish between the shifting to a lower gear that's commanded by the driver and the 'natural' automated downshifting that's programmed into the AT's shift schedule.

Automatics always used to downshift on closed throttle where there was no throttle-up being commanded. With torque converters either not having any lockup feature at all, or only in the upper gears during cruise conditions, they could allow as much slip as necessary. Driveshaft rpm would not be in fixed lock-step with crankshaft rpm

I have a strong suspicion that torque converters in the newer automatics tend to remain locked up under a far wider range of circumstances (for mpg and possibly emissions reasons), which does lock driveshaft rpm to crankshaft rpm. Now, even when the AT downshifts on its own programming, engine rpm needs to be kicked up to avoid lurching and forward head-toss for the car's occupants.

Here's a little snippet from GM's description (titled "Holy Shift A Look inside GMs new 10 Speed Automatic
Advanced design, GM control system support capability, enhanced efficiency
2016-05-11")

Gear changes are mainly executed with clutch-to-clutch action, where an “on-coming” clutch is engaged and an “off-going” clutch is released in a precise manner to achieve the ratio change. Certain key shifts, however, are made with a freewheeling action, such as 3-1 downshifts, where a plate clutch is actively disengaged while a mechanical freewheeler clutch automatically engages with optimum synchronization.

Even "in a precise manner" sounds like it's using a few more engine revs.


Feel free to do further research along those lines, but it's really the only thing that makes engineering/product acceptability sense to me.

DickR may know something about this; I think it was him who gave me the lead to follow that ended up with the above..


Norm

 

[Schwerin]

I kept rev match, but hill assistant had to go on day 3. Thing kept making me stall out. Soon as I God rid of it, not a problem since.

 

[Sivi70980]

I kept rev match, but hill assistant had to go on day 3. Thing kept making me stall out. Soon as I God rid of it, not a problem since.

Agree. The hill assist thing works very erratic. Sometimes it does nothing and others it will keep you from moving forward. Also disabled it, I have zero issues with hills.

 

[Vlad Soare]

Besides, most of them are really nice and would be happy to hear what a real engine sounds like. We don't get to see too many V8s around here, and cops are as passionate about cars as anyone else. They would probably give my a thumbs up.

Speaking of this, let me give you a fresh example. It happened yesterday.
In Romania if you exceed the speed limit by more than 50 km/h (~31 mph) your licence gets suspended for between one and three months (the exact extent varies, and frankly I don't know the criteria). Up to that point you just pay a fine. So, I take care not to exceed that threshold. I don't care about fines (well, I do, but I can live with them), but I need my driver's licence.
The speed limit on motorways is 130 km/h. So, I take care not to exceed 180 km/h.
Yesterday, on a motorway, I thought I spotted a speed trap. Sure enough, it was a speed trap. They pull me over, ask me to wait while they write the ticket, and five minutes later one of them comes over to my car to hand me my documents back and the ticket. Here's how the conversation went:
Me: "How fast was I going?"
"171. Kind of slow... for this car"
"Well, I took care not to exceed 180, to keep my licence"
"Ah, I see. Is this really a GT?"
"Yes, it is"
"I mean, it's not a 2.3 liter or something like that"
"No, it really is a five liter"
"Nice. Exactly how it should be. Where are you going?"
"Brașov."
"OK then, now that you've paid, you can go" (this sentence may not mean much in English, but the words he used, and his tone, were a subtle hint that there were going to be no more speed traps on the way to my destination)
"Thank you."
"When you drive off, please step on it hard. Make it sound nice and loud".
"Will do."

While I fumbled with my documents for a few seconds, he started walking back to his car. He was walking slowly, looking over his shoulder, waiting for me to drive off. I turned on the engine, put the exhaust in Track and drove off as if my life depended on it. Took it to 7000 rpm in first gear, then 6000 rpm in second. I hope he liked it.

Epilogue: knowing that there would be no more speed traps, I let my guard down and drove as fast as I could. Traffic was light, but there was still enough of it to keep me from reaching the GT's top speed. I managed to get to 248 km/h once, before having to slow down a bit due to traffic. 200-210 km/h was doable though, and I did it. It was great. One of the best moments of my life. And all thanks to that nice cop, who subtly encouraged me. The fine was a small price to pay for this joy.

 

[shogun32]

The hill assist thing works very erratic. Sometimes it does nothing and others it will keep you from moving forward

you already had hill assist - that lever thingy that the uneducated call a parking brake.

 

[Vlad Soare]

that lever thingy that the uneducated call a parking brake.

You mean the drift lever?

 

[Sivi70980]

you already had hill assist - that lever thingy that the uneducated call a parking brake.

Pffftt lol. I never did use the e brake for help. Only for 180’s. I never really remember having issues with the car rolling back. I think there were only a few times when I was super new when I burnt the hell out of the clutch but that was eons ago.

 

[MikeMr305]

I know this is the unpopular opinion, but i had the confidence to buy a manual because of the assists. I learned to drive stick 2 years ago the day i bought my veloster N on the drive home. Stalled 10 times, made a fool of myself constantly, but i was terrified of the thought of money shifting and destroying a brand new car. 2 years later id consider myself a good manual driver even in heavily spirited drives and emergency situations, and now im in a 2019 6 speed GT because i cannot imagine a commute with an automatic (went out of my way to make sure it was a 2019 specifically because of the rev matching). the transmission feel and rev matching are so much better on this, and i just use it for lazy daly driving and being obnoxious while pulling up to red lights
I understand that im not a hardcore purist, im literally just a casual nerd who likes to shift my own gears, and appreciates the help from technology.
IMO these features help bring new people into manuals that otherwise would never have bought one like myself, so they keep the manuals alive if even for a little longer. Im all for choice though, so i appreciate that they usually make the feature easily toggled by a button or a menu selection.
Some make it harder than others. I hear the type r really hides it in the menus and has it On by default lol

 

[Sivi70980]

I know this is the unpopular opinion, but i had the confidence to buy a manual because of the assists. I learned to drive stick 2 years ago the day i bought my veloster N on the drive home. Stalled 10 times, made a fool of myself constantly, but i was terrified of the thought of money shifting and destroying a brand new car. 2 years later id consider myself a good manual driver even in heavily spirited drives and emergency situations, and now im in a 2019 6 speed GT because i cannot imagine a commute with an automatic (went out of my way to make sure it was a 2019 specifically because of the rev matching). the transmission feel and rev matching are so much better on this, and i just use it for lazy daly driving and being obnoxious while pulling up to red lights
I understand that im not a hardcore purist, im literally just a casual nerd who likes to shift my own gears, and appreciates the help from technology.
IMO these features help bring new people into manuals that otherwise would never have bought one like myself, so they keep the manuals alive if even for a little longer. Im all for choice though, so i appreciate that they usually make the feature easily toggled by a button or a menu selection.
Some make it harder than others. I hear the type r really hides it in the menus and has it On by default lol

Also specifically got a 2019 for the auto rev matching feature. The biggest help for newer drivers imo is the anti stalling thing but if you get too used to it or only driven a car with it, the chance is greater that you'll have issues if you drive an older car without it. I'm comfortable and confident in most things manual but those older era manuals need different timing and finesse for sure.

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