Rev hang question

[sms2022]

Someone tell me if this is just in my head.

In normal exhaust mode, the revs hang longer on shifts so I have to shift slower.

in track exhaust mode (wide open) revs drop immediately.

this is not drive mode dependent. Am I imagining this or has anyone else experienced this?

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[JetGray_Mach1]

I have the Mach 1 but I report 0 revhang in any mode. You do have a tune must be tune related.

 

[shogun32]

I guess normal mode has too much back-pressure? But the coyote in general as delivered by Ford has a rev-hang problem to varying degrees. Even with rev-match OFF, the rev-match for upshifts is still active, at least on the Mach1 (grrrr), so that helps to quell rev-hang somewhat.

You owe it to yourself to get a quality tune regardless since Ford factory tune is not very good .

 

[RiotfunK]

I notice rev hang regardless of mode. I always run in sport+ so the throttle is better but the mag ride isn’t solid and the exhaust set to track. I’ll try track later and see. But I always have to wait a sec after depressing the clutch for them to fall to shift smoothly. I hate rev hang and find it instantly noticeable in newer vehicles. Had a civic Si I sold after few thousand miles because it was so bad.
Does rev match on or off make it any better or worse? I’ll have to experiment with the modes more to see if I can kill it as much as I can without a tune.

 

[sms2022]

I have the Mach 1 but I report 0 revhang in any mode. You do have a tune must be tune related.

It’s not tune related the car had horrible rev hang stock. It’s much better now with the tune. I think it’s rev match related. I’ll have to try toggling it off for awhile.

 

[shogun32]

It’s not tune related the car had horrible rev hang stock. It’s much better now with the tune.

yes and no. WHOSE tune and is it any good?
The tune param can be adjusted to kill that rev-hang crap 'stronger'.

I think Ford changed default behavior on rev-match *capable* cars so that on up-shift you can never actually disable it. So if you like to 1->3, or 2->4 you catch the computer out and it takes a moment to command the new lower RPM based on new gear selector gate being tripped.

my '19 GT doesn't do this because it's old school. I think Ford patted themselves on the back by interfering with driver action somewhere around '21 or '22. I guess when your software engineers are sitting at home bored, they invent things to change.

 

[sms2022]

yes and no. WHOSE tune and is it any good?
The tune param can be adjusted to kill that rev-hang crap 'stronger'.

I think Ford changed default behavior on rev-match *capable* cars so that on up-shift you can never actually disable it. So if you like to 1->3, or 2->4 you catch the computer out and it takes a moment to command the new lower RPM based on new gear selector gate being tripped.

my '19 GT doesn't do this because it's old school. I think Ford patted themselves on the back by interfering with driver action somewhere around '21 or '22.

That would make a lot of sense. My tune does kill 90% of the rev hang, 99% of it until the computer relearns my driving habits. If I shift like Steve McQueen while it’s learning it stays with no rev hang for quite awhile.

part of the issue could be rear tire size mismatch with the pcm. I’ll have to relearn it in forscan then reflash my tune and see if that fixes it.

 

[shogun32]

part of the issue could be rear tire size mismatch with the pcm.

just how far off stock 27" dia are you? This could easily be a contributing factor because it's setting the new revs to what it thinks the tire size needs. You'd think it could look at a trans output shaft sensor and do the math that way, but apparently that was an equation too far.

 

[GrayS550]

I can’t stand revhang. It’s so bad in the 100mph range. From 4th to 5th gear high RPM, it slams it into gear. Will an aftermarket clutch fix revhang or is it programmed into the ECU?

 

[shogun32]

is it programmed into the ECU?

Ford programmed it into the ECU. There are some valid reasons (gd EPA) for doing so, but it just pisses off the driver IMO.

extra spinning weight (dual-plate clutch etc) has to be overcome to a point and a lighter clutch rotating assembly can probably help, but it'll be pretty minor. It's all in the GD tuning.

 

[sms2022]

just how far off stock 27" dia are you? This could easily be a contributing factor because it's setting the new revs to what it thinks the tire size needs. You'd think it could look at a trans output shaft sensor and do the math that way, but apparently that was an equation too far.

Stock diameter is 27.7. I’m at 26.2 inches.
so it’s about a 150rpm difference at 70mph in 4th.

 

[ice445]

My car magically ceased its rev hanging behavior one day, it's pretty nice. I have my ture size set accurately though so maybe that helps

 

[sms2022]

Yeah come to think of it I bet it’s the tire size issue. Time to go to work in forscan and see if I can get the pcm to relearn it before reloading my tune.

 

[shogun32]

Stock diameter is 27.7. I’m at 26.2 inches.
so it’s about a 150rpm difference at 70mph in 4th.

hmm, so shouldn't your computer-commanded revs be lower than needed?

In any event, use Forscan to set the value more correctly. Your tune should automatically incorporate the new numbers on bootup.

Report back.

 

[sms2022]

hmm, so shouldn't your computer-commanded revs be lower than needed?

In any event, use Forscan to set the value more correctly. Your tune should automatically incorporate the new numbers on bootup.

Report back.

What it seems to be doing is hunting for the right Rpm. Mostly it rev hangs, sometimes it drops the revs too far. It basically has no clue. But it will sit the revs at a set rpm if I stop mid shift so that’s clearly what it’s doing. I just drove to lunch and verified that.

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