Annoying rev hang in my MT car

[jurko]

I always had cars with MT and I really like my manual Golf. But there's one very annoying issue with electronic throttle body control which creates rev hang and causes terrible jerkiness during the upshift which is most noticeable going from 1st to 2nd and from 2nd to 3rd gear.

I found couple of ways to deal with this.
1) Wait for about 2-3 seconds after the clutch pedal is depressed at which point the RPM goes finally down and than do the upshift.
2) Or by double clutching method.

If you have a car with MT do you experience the same issue?
Before the introduction of drive by wire the throttle body was triggered by cable and rev hang was never a problem.

 

[Propflux01]

I had a 1982 Dodge Colt that did this very thing. Emissions equipment made the engine hang RPM for a couple seconds as not to produce a sudden rich mixture upon decel and the resultant squirt of extra fuel when accelerating into the next gear. I would imagine this same type of control is being used in your Golf.

 

[vwmaniaman]

Propflux01 is correct. Emissions

 

[Smoky14]

Ah yes, welcome to the wonderful world of drive by wire. My Fusion does the same thing and will not close the throttle plate when coasting so I effectively have no compression braking which hampers mountain driving.
I feel your pain

Smoky

 

[supton]

Yes.

I don't recall my Saturn having this; my diesel sure didn't. Wife's Camry has it and whenever I drive it, I just have to remember to go slowly on shifting--push clutch in, change the radio station, sing happy birthday to myself and then it's about where it needs to be.

If I were to buy another stick I might do some shopping around and see what models have aftermarket tunes, with the intent of finding one where this feature could be tuned out. That's not to say all cars do this (see aforementioned Saturn); perhaps some of the better makes got around this through other means (or lived with the momentary burp because their cars ran cleaner the rest of the time--it's all about emissions per mile and thus if they shave here then they can emit there).

 

[Quattro Pete]

The rev hang issue is not really a result of drive by wire as it is a result of modern emissions requirements, as was mentioned. Early DBW cars like my 530i do not exhibit this rev hang behavior.

But yes, DBW made this behavior possible in later years.

 

[Cujet]

Custom tunes can help with this. But you might have to ask specifically for a direct pedal to throttle match.

The throttle response from many modern engines is so poor, I find the accelerator to be just a "suggestion pedal". On some vehicles, I can mash the pedal, remove my foot and place it flat on the floor mat before any response happens!

Same goes for lift throttle. I remove my foot and it's as if I left it there! Good god that annoys me.

Making matters worse, cars like the Camaro SS, open the throttle too much on initial tip-in, then back off suddenly, making it impossible to drive in a sporty manner. It's either slow or full throttle. Ugh.


Sometimes the light turns green and the Mercedes in front of you just seems to sit there. It's not the driver, it's the 3 second lag, tuned into the system!

 

[WylieCoyote]

I mitigate it a little by adjusting my pedal timing. My ST hangs, so I've trained myself to release the gas a second before I depress the clutch. Doing it this way gets the clutch depressed just as the engine starts to transition from acceleration to deceleration. It helps.

 

[Greasymechtech]

Emissions rev hang.... common to many brands over the couple decades

Some fancier cars have rev match to help, like the Toyota Corolla(since you were thinking BMW, Porsche, sports cars, or exotics).

I've gotten so use to my VW that I don't even notice the rev hang anymore. Maybe it learned or maybe my foot adapted. But, it still has no compression braking and can coast forever.

 

[TrainingPolicy]

Double clutching? If your VW Golf has synchros (which it most likely does) then I dont see how double clutching affects Rev hang? Typically rev hang is a computer controlled thing to help ‘stay in the power band’ when changing gears or like others stated, for vehicle emissions. I have heard of people putting a tune on a car and it eliminating the rev hang.

 

[SwampSurvivor]

Throttle snap shut combined with the engine slowing down is not good for emissions so they have to program that out.

My Forester isn't PZEV so it's not as bad, but my Focus was awful .

Double clutching won't do much other than lower the engine RPM by the drag of spinning the trans input shaft with the clutch out. The throttle has to stay open a certain percent; it's not aiming for a certain RPM.

 

[DwightFrye]

I had a 2009 Nissan 370Z with the 6MT. Besides having a horrible feeling clutch, it also had a lot of rev hang. I had read that was caused by a heavy flywheel which was designed in to smooth out the engine. People who modded their cars by switching to a lighter flywheel reported much improved engine response. Although maybe they also did some kind of tune that changed the throttle mapping ?

 

[slacktide_bitog]

Throttle snap shut combined with the engine slowing down is not good for emissions so they have to program that out.

My Forester isn't PZEV so it's not as bad, but my Focus was awful .

Double clutching won't do much other than lower the engine RPM by the drag of spinning the trans input shaft with the clutch out. The throttle has to stay open a certain percent; it's not aiming for a certain RPM.

Subaru still sells non-PZEV Foresters?

 

[ecotourist]

Early DBW cars like my 530i do not exhibit this rev hang behavior.

My 2000 528i supposedly has a rev hang problem that has an easy mechanical fix. But I've never found it to be noticeable, so I've never applied the fix.

 

[SwampSurvivor]

Subaru still sells non-PZEV Foresters?

Yeah. Some of the 6MT Foresters (up to 2018) are non-PZEV. I'm not sure what the difference is but looking on car-part.com I am seeing that some have EGR with an EGR cooler and some do not. I'm assuming mine is latter that doesn't have the extra EGR stuff on it. I've honestly never checked to see if it even has EGR or the EGR Cooler on it but always assumed it didn't being non-PZEV

 

[Quattro Pete]

My 2000 528i supposedly has a rev hang problem that has an easy mechanical fix. But I've never found it to be noticeable, so I've never applied the fix.

Are you referring to the CDV (clutch delay valve)? If so, I believe this valve was put in there to help inexperienced manual trans drivers avoid stalling the car if they release the clutch too quickly and generally protect the drivetrain. Unfortunately, it made it annoying for everyone else - doing quick but smooth clutch releases was impossible to do. I had my CDV removed soon after I bought the car, and it did make clutch engagement more predictable.

 

[dfarr67]

2015 Honda Accord Sport 2.4L 6MT- bought a Ktuner specifically for this issue, but also threw a premium octane tune and rear O2 sensor delete at it. That rev flare is annoying. The V6 models had hydraulics that made for the flare.

 

[Greasymechtech]

Clutch accumulator aka the vague shock absorber.... remove it

Lightflywheel.... every hear a VW with the DMF removed for a SMF? Some sound like the worst idling rod knock ever even though its just a transmission harmonic. You'll hear this from at least 1 gearhead.... is that a diesel or rod knock? no, its just SMF. The rev hang will be there but the lighter mass means a little less jerkiness. How heavy is the DMF compared to an SMF conversion? Waiting on my clutch to fry before swapping in something different

Less jerkiness..... real motor/drivetrain/transmission mounts.... or at least the poly insert for the dogbone

Drivebywire..... beating a dead horse.... we're stuck with it unless you want to install an aftermarket ecu and throttle cable. Everytime I drive a car with a throttle cable, the control is intoxicating.

 

[ecotourist]

Are you referring to the CDV (clutch delay valve)? If so, I believe this valve was put in there to help inexperienced manual trans drivers avoid stalling the car if they release the clutch too quickly and generally protect the drivetrain. Unfortunately, it made it annoying for everyone else - doing quick but smooth clutch releases was impossible to do. I had my CDV removed soon after I bought the car, and it did make clutch engagement more predictable.

Yes I believe you're correct, a clutch delay valve.

I've never found the clutch action annoying. I bought mine used so it may have been fixed before I got it.

I got mine with 50,000 Km for something like 40 - 45% of the replacement price. It seemed like a good idea at the time but now I wish I had bought it new. I have a bit of rust that wouldn't have happened in my hands. And now BMW doesn't make what I'd buy to replace it (larger sedan, I6, manual transmission, spare tire, engine oil dip stick).

 

[jurko]

Double clutching? If your VW Golf has synchros (which it most likely does) then I dont see how double clutching affects Rev hang? Typically rev hang is a computer controlled thing to help ‘stay in the power band’ when changing gears or like others stated, for vehicle emissions. I have heard of people putting a tune on a car and it eliminating the rev hang.

The double clutching method works for me and drop in RPM happens fast. Let's say I am in 1st, rev it up to 3K RPM shift to neutral release the clutch, then depress the clutch again and upshift to 2nd. I sometimes do it the other way as I described in my post if I don't feel like stepping on clutch pedal twice between gear upshift change.