7MT Extreme Rev Hang

[wetdog]

Idle too high?

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[jasonkosi]

After further research..!

First of all: idles at 800-1200. Seems pretty high to me.

Second of all, and this is quite astounding to me: Clutch out in first gear while I’m giving it no gas does not stall the car. In fact the car just starts moving. This means it must be getting some throttle input without me doing anything right?
Anyone else with a MT that can test that? It definitely should stall right??

Well 2 things, one being the gearing is low - 4.46 so you get good torque multiplication. Second being, and I just recently learned this is common on many modern manual vehicles, is the ECU tells the engine to give a little throttle when the clutch begins to catch, even without you pressing the accelerator. If you look at the tach when you let out the clutch in first, the revs will go from idle - 800rpm - to about 1100 as the clutch catches.

And yes, regular idle speed once warm is 800 rpm. I’m guessing that’s just due to being a smaller motor

 

[BroncoAZ]

No such issue on mine.

 

[bronco100]

I wonder if anyone else has watched their tach when pressing clutch in? How long does it take you to go from 5k rpm to 2k? (No gas or brake or anything, just clutch all the way in and hold it there while revs drop)

 

[DesertMike680]

Glad this was brought upo

I wonder if anyone else has watched their tach when pressing clutch in? How long does it take you to go from 5k rpm to 2k? (No gas or brake or anything, just clutch all the way in and hold it there while revs drop)

I'm going to pay more mind to this on my Big Bend, so I'm glad this was brought up. On another note, when you put your foot on the gas and let go, do you hear a loud, "click" once releasing the gas? It kind of sounds like a solenoid opening/closing. I took it to my dealership, he verified the noise but couldnt find where it was coming from. He replaced the BPV but that obviously wasnt the issue. I had a few local, Bronco guys listen to it and they said it sound like a vacuum leak.

Lastly, my clutch pedal is starting to "creak" when released. Like, it needs a little bit of grease.....Stupid.

 

[Brnzbronc]

This is normal, if you press in the clutch the RPMs will rise for you. If you’re an old school manual driver you will have to adjust to how you drive it. Your first instinct is to press the gas and release the clutch at the same time but really you just need to release the clutch out first then momentarily ease into the gas. When I first started driving mine I thought the transmission was super clunky until I realized about the rev matching feature. So when you’re shifting the rpms hang where you left off to smooth the shift transition so it not so jerky.

 

[Bigguyry2000]

This is normal, if you press in the clutch the RPMs will rise for you. If you’re an old school manual driver you will have to adjust to how you drive it. Your first instinct is to press the gas and release the clutch at the same time but really you just need to release the clutch out first then momentarily ease into the gas. When I first started driving mine I thought the transmission was super clunky until I realized about the rev matching feature. So when you’re shifting the rpms hang where you left off to smooth the shift transition so it not so jerky.

My 21 doesn't rev match at all (unless I'm doing it on the downshift). Do you have the ford performance tuner? That supposedly has the option on downshifts.

I've shifted mine without even using the clutch 2nd to 3rd, 3rd to 4th to 5th and 6th. So unless there is a rpm match program that rev matches maybe it only does it when using the clutch. I don't do it often, so don't trip out on me lol. But I've been driving manuals for a long time so its all pretty easy at this point.

OP: have you tried not using the clutch at all and seeing if that effects your rpm hang issue? Or did the dealer get everything sorted out?

 

[BigFootie]

I’ve driven manual transmissions my whole life. I’m not sure I get where there is a problem. You want to match the rpm’s to where the next gear will be. That certainly won’t be 800rpm in 4th gear. In an ideal state, the rpm of the clutch will engage at the same rpm the engine is.

 

[Bigguyry2000]

I’ve driven manual transmissions my whole life. I’m not sure I get where there is a problem. You want to match the rpm’s to where the next gear will be. That certainly won’t be 800rpm in 4th gear. In an ideal state, the rpm of the clutch will engage at the same rpm the engine is.

From his posts, the OP seems to be having an issue where his RPMs aren't falling in order to match the engine speed to the trans input shaft speed.

 

[BigFootie]

From his posts, the OP seems to be having an issue where his RPMs aren't falling in order to match the engine speed to the trans input shaft speed.

Ok, I reread his original post. I’ve only driven a couple of 7MT Broncos as I’m still waiting for mine to get built some year. Both had the 4.46 and one with true 35’s and one with the 32’s. Didn’t notice anything strange but I started out on a 55 Chevy with a three on the tree and mostly only have had manual transmissions. I will say you can definitely side step the clutch in 1st “crawl” and not stall but that’s because of the gearing, not rpm’s. Also, the modern ECU’s will help you from stalling. The people that test drive the Big Bend with 35’s did seem to have trouble starting but never stalled it but it lugged a lot.

 

[kodiakisland]

Rev hang and rev match are not the same thing. It’s EPA programming and very annoying when it happens. Thankfully my Bronco doesn’t.

 

[Brnzbronc]

My 21 doesn't rev match at all (unless I'm doing it on the downshift). Do you have the ford performance tuner? That supposedly has the option on downshifts.

I've shifted mine without even using the clutch 2nd to 3rd, 3rd to 4th to 5th and 6th. So unless there is a rpm match program that rev matches maybe it only does it when using the clutch. I don't do it often, so don't trip out on me lol. But I've been driving manuals for a long time so its all pretty easy at this point.
Yeah mine revs match with every shift, if I hold in the clutch for more then I’m guessing 3 seconds the rpms will drop. Now if you double clutch shift it doesn’t rev match. I don’t have the Ford performance tune yet but I will eventually get it. Maybe it’s different with the models since I have a base it’s not an option to turn off rev matching.. I haven’t really dug into it.
OP: have you tried not using the clutch at all and seeing if that affects your rpm hang issue? Or did the dealer get everything sorted out?

 

[bronco100]

You don't need to reply if you don't know what you're talking about. I'm not referring to rev matching, or shifting without the clutch or 99% of the other things the folks in the replies of this thread are talking about. I'm only inquiring about rev hang. That's it. Thanks

 

[cyberfalco]

I've never heard of this before, huh.

Anyway, yeah my Bronco shift way differently than any other manual I've ever had. I was well into 3000 miles before I got really comfortable with it.

Jumping back into the 2011 JK is an eye opener each time.

 

[cyberfalco]

The only thing I can think of is your throttle position sensor needs to be recalibrated.

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