COBB vs Mountune for eliminating Shift Assist / Rev Hang

[92083420938420]

I don't care about power at all - most days I'm stuck in traffic anyways. But when I do finally get my 1 or 2 chances per commute to really open it up the shift assist bullshit in the ECU completely kills whatever fun I would've had in that moment.

I know that Mountune has an option when selecting your access port to 'disable' the 'shift assist' which is exactly what I'm looking for as long as it can completely disable the shift assist.

I've heard that the COBB tunes have a harder time disabling the feature and that it's still somewhat enabled? If so, this would be a deal breaker for me. I don't see an option to customize the tune with the Stage 1 kit on the COBB website so maybe I missed that. I also saw screenshots from 2016ish? that didn't show the 'shift assist' as an option to disable through the access port so that was a bummer as well.

Here's the Mountune package I'm referring to: https://www.mountuneusa.com/COBB-V3-Accessport-ECU-Flasher-Fiesta-ST-p/ap3-for-001fa1.htm

EDIT: After poking around a bit I can see that in the map notes for the COBB tune there's references to disabling the rev hang here: https://cobbtuning.atlassian.net/wiki/spaces/PRS/pages/96996737/Ford+Fiesta+Map+Notes

So my question is: who has done a better job of completely eliminating the rev hang? COBB or Mountune?

 

[Joker328]

I'm not sure "shift assist" should affect your ability to really open it up. It only really comes into play when you are granny shifting as it keeps the revs from dropping below what is needed for the next higher gear when you clutch in. When you are shifting quickly, they will never drop that low before you shift into the next gear. Your issue seems more like rev hang. It is pretty bad on the stock tune, probably for environmental reasons. Slapping the throttle closed quickly tends to create some serious pollutants so they program it to not do it quite as quickly, resulting in momentary rev hang. I haven't used the CobbOTS tunes in a while, but I seem to remember they had mostly dialed this out. Now, as you mention, it looks like there is a toggle for it, so perhaps they improved it further or just made it optional. I can't speak for Mountune. However, it's worth mentioning that there will always be some amount of rev hang regardless of tune simply due to the heavy dual mass flywheel. You'll never really get rid of it without switching to a lighter flywheel, but that could negatively impact driveability and mileage.

 

[Jason@dizzytuning]

All Cobb maps prior to v500 had rev hang enabled.
On the v500 maps they disabled rev hang, but give you an option in ATR (if you have it) to enable it, if desired.
So you should be able to load the v500 map without issues. But if it’s still there, feel free to shoot me a message and I’ll disable it for you in the map.

 

[92083420938420]

I'm not sure "shift assist" should affect your ability to really open it up. It only really comes into play when you are granny shifting as it keeps the revs from dropping below what is needed for the next higher gear when you clutch in. When you are shifting quickly, they will never drop that low before you shift into the next gear. Your issue seems more like rev hang. It is pretty bad on the stock tune, probably for environmental reasons. Slapping the throttle closed quickly tends to create some serious pollutants so they program it to not do it quite as quickly, resulting in momentary rev hang. I haven't used the CobbOTS tunes in a while, but I seem to remember they had mostly dialed this out. Now, as you mention, it looks like there is a toggle for it, so perhaps they improved it further or just made it optional. I can't speak for Mountune. However, it's worth mentioning that there will always be some amount of rev hang regardless of tune simply due to the heavy dual mass flywheel. You'll never really get rid of it without switching to a lighter flywheel, but that could negatively impact driveability and mileage.

Thanks for the clarification. I've been reading all day today and think I've narrowed it down to 3 issues:

1) Shift assist holds the revs at a floor to avoid missing up-shifts.

2) Revs take a while to start dipping after releasing the throttle for emissions purposes - known as 'rev hang'.

3) Revs fall awfully slow. Unbelievably slow. Undriveably slow actually. No other manual I've owned in history has had such lazy revs. This hugely impacts spirited driving or requires you to burn out your clutch whenever you wanna race someone.

All Cobb maps prior to v500 had rev hang enabled.
On the v500 maps they disabled rev hang, but give you an option in ATR (if you have it) to enable it, if desired.
So you should be able to load the v500 map without issues. But if it’s still there, feel free to shoot me a message and I’ll disable it for you in the map.

That's a very generous offer Jason thanks. Can you confirm if the COBB map can help with issue #3 that I've clarified? I know #1 and #2 are easy to change with tuning but I'm wondering if what I really need is a new flywheel instead of a tune. It's the laziness of the revs that impacts my driving first and foremost so I'd like to tackle my issues top to bottom.

I think fixing #2, 'rev hang', is a great start for a tune but not the whole solution to the problem of spirited shifting being incredibly difficult to pull off in this car without burning out the clutch.

 

[zucky22389]

FWIW- I bought Mountune FB1 pack and chose to disable shift assist on the customization screen. I installed my stage 1 93 octane map and see absolutely zero improvement in rev hang. Is there a separate option in the ap3 I'm missing? Just letting you know I've experienced no improvement over stock with tune.

Sent from my SM-G950U using Tapatalk

 

[Jason@dizzytuning]

Thanks for the clarification. I've been reading all day today and think I've narrowed it down to 3 issues:

1) Shift assist holds the revs at a floor to avoid missing up-shifts.

2) Revs take a while to start dipping after releasing the throttle for emissions purposes - known as 'rev hang'.

3) Revs fall awfully slow. Unbelievably slow. Undriveably slow actually. No other manual I've owned in history has had such lazy revs. This hugely impacts spirited driving or requires you to burn out your clutch whenever you wanna race someone.





That's a very generous offer Jason thanks. Can you confirm if the COBB map can help with issue #3 that I've clarified? I know #1 and #2 are easy to change with tuning but I'm wondering if what I really need is a new flywheel instead of a tune. It's the laziness of the revs that impacts my driving first and foremost so I'd like to tackle my issues top to bottom.

I think fixing #2, 'rev hang', is a great start for a tune but not the whole solution to the problem of spirited shifting being incredibly difficult to pull off in this car without burning out the clutch.

That’s honestly very strange. I’ve owned nothing but manual vehicles in my 18 years of driving, and did not notice any of these things with the Fiesta. I did notice the rev hang when you let off in any gear, but it had zero effect on my driving habits.

Are you saying that when you push in the clutch in any gear, the revs fall very very slow? Can you post a video of this?

 

[zucky22389]

You get used to it. I've owned 5 manuals over 10 years prior to the ST and this is the most unnatural feeling one due to what feels to be electronically controlled rev hangs and delayed falling engine speeds during upshifts. Made it very difficult to drive smoothly at first unless literally holding in the clutch for 2 seconds while drop occurred. Still my biggest quibble with the car but again, you get used to it. And during all my hours of surfing this forum, I have not seen a definitive solution by anyone!

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[SlowDunny]

You get used to it. I've owned 5 manuals over 10 years prior to the ST and this is most unnatural feeling one due to what feels to electronically controlled rev hangs and delayed falling RPM.

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Agreed, I like to go 4th gear to 6th gear when merging on the highway and the rpms do not want to fall as fast as I want to shift to 6th.

I wish I had the v500 maps instead of the v504 just for this to be switch off.

 

[alexwlwsn]

Yeah only time I've ever noticed an issue with the rev hang is when skipping gears. Other than that I'd say the driving experience is pretty normal. Sure, it doesn't act like my Miata with a real throttle cable but it's nowhere near an annoying driving experience.

 

[Jason@dizzytuning]

You get used to it. I've owned 5 manuals over 10 years prior to the ST and this is the most unnatural feeling one due to what feels to be electronically controlled rev hangs and delayed falling engine speeds during upshifts. Made it very difficult to drive smoothly at first unless literally holding in the clutch for 2 seconds while drop occurred. Still my biggest quibble with the car but again, you get used to it. And during all my hours of surfing this forum, I have not seen a definitive solution by anyone!

Sent from my SM-G950U using Tapatalk

Looks like I have work to do!

 

[SirThomas88]

I've also been searching online for a solution for this "rev hang." People on these forums do often get it confused with "shift assist." Where shift assist doesn't really get in the way of spirited driving, the rev hang is definitely a bummer.

It's most noticeable if you release the gas pedal and depress the clutch at the same time, the revs will actually continue to climb slightly for half a second before it begins to drop!

It seems like there really isn't any solution available yet for this. When it comes time to replace my clutch, I'll likely take the opportunity to install a lightweight flywheel to try to negate the terrible rev-hang.

However, it's worth mentioning that there will always be some amount of rev hang regardless of tune simply due to the heavy dual mass flywheel. You'll never really get rid of it without switching to a lighter flywheel, but that could negatively impact driveability and mileage.

Really? Could you elaborate on how it can negatively impact drive-ability and mileage? I'm not familiar with dual-mass flywheels. but my first manual had a light-weight Fidanza flywheel, the only concern I heard of was that it's a little easier to stall out when shifting from neutral to 1st but that never was a concern for me.

I do wonder if the lightweight flywheel could actually make the rev-hang worse and make the tendency for the revs to climb after depressing the clutch even more dramatic!

 

[Joker328]

You hit on #1, which is potential for stalling from a stop, but that is something you can deal with through driver mod (i.e. giving it more gas). #2 is that the dual mass flywheel has springs that dampen some engine vibration so that it doesn't reach the transmission and create lash in the transmission itself. It also absorbs some of the difference in rotation speed between the crank and input shaft when you shift, so while the weight can make the revs fall slower, the springs help reduce the impact of it. #3 is mileage, which could go either way depending on your driving style and vehicle use. The flywheel stores energy so more weight equals more energy stored (this is why revs drop slower with a heavier flywheel). So when you let off the gas while in gear, you decelerate less and you can coast further with a heavier flywheel. If you're doing a lot of highway driving, this is probably a net benefit. However, if you are doing more city driving and on the brakes a lot anyway, the penalty from having to spin up a heavy flywheel could make your mileage worse.

 

[TrickSTer]

My car is almost 3 years old, 75K km (47k miles); stock. I no longer notice any rev hang or shift assist. My driving style, whether spirited or casual, is to shift extremely smoothly, such that others can barely feel the shift (a girl I worked with once was adamant with my cohorts that my car was an automatic; she'd driven with me a lot and she KNEW). I have no problem driving this style with my car.
The only way you should even notice rev hang/shift assist is if you're shifting extremely slowly
I am thinking that rev hang is something the ECU does while it is "learning" your driving style (I did notice it when the car was new).
Just drive it, it won't affect the longevity of your clutch.

Lightweight clutches/torque converters: I was amazed when I reved an AMG E63, to the floor and let off: the engine goes WHUMP and is back to idle as fast as you can say that word!

 

[cxwrench]

You get used to it. I've owned 5 manuals over 10 years prior to the ST and this is the most unnatural feeling one due to what feels to be electronically controlled rev hangs and delayed falling engine speeds during upshifts. Made it very difficult to drive smoothly at first unless literally holding in the clutch for 2 seconds while drop occurred. Still my biggest quibble with the car but again, you get used to it. And during all my hours of surfing this forum, I have not seen a definitive solution by anyone!

Sent from my SM-G950U using Tapatalk

Seriously? I can't stand the 'rev hang' either but there is no way it's any kind of impediment to driving/shifting. I've never ever felt the need to wait for revs to drop to upshift.

Background: Nearly 40 years of manual gearbox experience including racing moto, shifter kart, and autocross.

 

[zucky22389]

Seriously? I can't stand the 'rev hang' either but there is no way it's any kind of impediment to driving/shifting. I've never ever felt the need to wait for revs to drop to upshift.

Background: Nearly 40 years of manual gearbox experience including racing moto, shifter kart, and autocross.

Yes seriously! I was referring to maybe the first week or two of ownership here. This was a new phenomena for me at that time and it felt like the drop took a lifetime and made it difficult to drive smoothly until I got used to it. I came from a silky smooth gearbox from BMW prior to this, so perhaps I was spoiled

 

[92083420938420]

That’s honestly very strange. I’ve owned nothing but manual vehicles in my 18 years of driving, and did not notice any of these things with the Fiesta. I did notice the rev hang when you let off in any gear, but it had zero effect on my driving habits.

Are you saying that when you push in the clutch in any gear, the revs fall very very slow? Can you post a video of this?

I will try to record some videos this week but it takes over 2 seconds to rev match from 1st to 2nd gear at high RPMs. Having owned a Miata, a Genesis Coupe, an Exige, and a WRX, and none of them had this issue. The very heavy flywheel causes the revs to fall at an appallingly slow rate. This combined with the momentary 'rev hang' when getting off the gas is a recipe for disaster in the FiST. It make spirited driving extremely disappointing and actually detrimental to the clutch as it is forced to pick up the slack.

FWIW- I bought Mountune FB1 pack and chose to disable shift assist on the customization screen. I installed my stage 1 93 octane map and see absolutely zero improvement in rev hang. Is there a separate option in the ap3 I'm missing? Just letting you know I've experienced no improvement over stock with tune.

Sent from my SM-G950U using Tapatalk

This is exactly what I was looking for as far as feeback. The issue you're noticing is the flywheel. A tune can remove the shift assist that holds the revs on upshifts and it can probably tune out the momentary pause after letting out the gas where the drive by wire system leaves the throttle open to burn out the rest of the fuel in the cylinders for emissions purposes. But a tune can't make the revs fall physically faster when it's a flywheel issue.

You get used to it. I've owned 5 manuals over 10 years prior to the ST and this is the most unnatural feeling one due to what feels to be electronically controlled rev hangs and delayed falling engine speeds during upshifts. Made it very difficult to drive smoothly at first unless literally holding in the clutch for 2 seconds while drop occurred. Still my biggest quibble with the car but again, you get used to it. And during all my hours of surfing this forum, I have not seen a definitive solution by anyone!

Sent from my SM-G950U using Tapatalk

Completely agree. Mechanically this is the worst manual car I've ever driven for these specific issues. It's just really unsatisfying when you try to do a really fun pull from 1st through 4th and you have 2.5 second gaps between shifts while you wait for the revs to fall. It's a massive buzzkill when driving spiritedly and it can't be overstated.

Agreed, I like to go 4th gear to 6th gear when merging on the highway and the rpms do not want to fall as fast as I want to shift to 6th.

I wish I had the v500 maps instead of the v504 just for this to be switch off.

A tune will probably not fix the issue that's bothering you. I'm leaning very heavily towards flywheel still as the main culprit of delayed shifting and slow revs falling.

Yeah only time I've ever noticed an issue with the rev hang is when skipping gears. Other than that I'd say the driving experience is pretty normal. Sure, it doesn't act like my Miata with a real throttle cable but it's nowhere near an annoying driving experience.

I don't want to rain on your parade because if you enjoy your car that's great but coming from an NC Miata it's worlds different. Either my 2017 flywheel is different than yours, you don't drive your car like a bat out of hell, or you just don't remember your miata's shifting experience because it was too long ago possibly? It's more than annoying - I don't even want to drive the car anymore. In fact it's up for sale right now and I'll probably take a $4000-$6000 loss - if I can even find a buyer.

Seriously? I can't stand the 'rev hang' either but there is no way it's any kind of impediment to driving/shifting. I've never ever felt the need to wait for revs to drop to upshift.

Background: Nearly 40 years of manual gearbox experience including racing moto, shifter kart, and autocross.

Don't wanna knock your driving experience here buddy but in any normal manual car if you up-shift too quickly the clutch will be used to pull down the revs from lets say 3rd to 4th. "Quickly" is 100% defined by how fast the revs fall. Ideally, when you up shift, the time it takes you to move the stick from one gear to the next is exactly how long it takes the revs to fall to rev-match into the next gear. This is not the case in the Fiesta in ANY gear. There's no single gear change in this car that you can do in a timely manner. You're always waiting for the revs to fall. 1st -> 2nd. 2nd -> 3rd. 3rd -> 4th. You always shift the stick faster than the revs can fall. That means you're always waiting for the car's revs to catch up. This is just poor design on Ford's part. And every time you wanna drive fast you have to burn out your clutch or lose momentum waiting for the revs to fall. Anyone who thinks this isn't a huge issue either doesn't have the issue, doesn't understand the issue, or doesn't know what the issue is. I'm not crazy and I'm willing to sell the car at a huge loss because it's so bad.

 

[alexwlwsn]

I don't want to rain on your parade because if you enjoy your car that's great but coming from an NC Miata it's worlds different. Either my 2017 flywheel is different than yours, you don't drive your car like a bat out of hell, or you just don't remember your miata's shifting experience because it was too long ago possibly? It's more than annoying - I don't even want to drive the car anymore. In fact it's up for sale right now and I'll probably take a $4000-$6000 loss - if I can even find a buyer.

LOL well I traded in my Miata on the FiST so I certainly remember driving it. Also, an NC isn't a real Miata

I definitely don't oftentimes drive the car like a bat out of hell, as it's my daily, but when I do hit back roads, I have never thought to myself the rev hang was bothersome. Comparing driving styles is completely useless though. If you don't like the car might as well sell it to someone who will enjoy it.

 

[zucky22389]

[MENTION=8203]92083420938420[/MENTION] - I went for maybe a 30 minute spirited run around Middle TN back roads on Saturday afternoon and the rev hang didn't totally kill the experience. I just pretty much burn the clutch while trying to make shifts as smooth as possible. I get it though man - It definitely did bother me at first when I bought the car. So much so that I called my enthusiast buddies to ask them about it to see what they said. I understand! But perhaps stick with it a bit longer. I haven't done research into this, but I'm curious the difference a lighter flywheel would make.

Cheers

 

[92083420938420]

LOL well I traded in my Miata on the FiST so I certainly remember driving it. Also, an NC isn't a real Miata

I definitely don't oftentimes drive the car like a bat out of hell, as it's my daily, but when I do hit back roads, I have never thought to myself the rev hang was bothersome. Comparing driving styles is completely useless though. If you don't like the car might as well sell it to someone who will enjoy it.

Looks like I'm stuck with it for now - Ford dealers and Ford themselves are giving massive incentives on 2018s before the car is discontinued in America which means used prices are plummeting...

 

[danbfree]

Looks like I'm stuck with it for now - Ford dealers and Ford themselves are giving massive incentives on 2018s before the car is discontinued in America which means used prices are plummeting...

$3000 rebates on '17's, which seem to be in huge numbers of what's available, and $2000 on '18's which literally only adds rear camera... Or, super low interest on either model instead if you qualify.. But ya, mostly '17's getting bigger discounts on top of just the rebate, it's quite easy to get one for $4000 under MSRP... I traded in a Forte5 SX for mine with a very similar motor and the Kia also had more rev hang than I was used to at first, but either the ECU, or you as the driver, learns, but it does get better in time.