Rev hang, any ideas?

[pierresmith]

Hi Gents,

I have a 2011 Transit Connect 1.8tdci , been a bit of a project this year, pretty much finished now and took it for a road test a few days ago.
Drives nice except for one thing, when changing up through the gears it seems to have rev hang, when taking foot off the gas to change gear the revs don't drop off as quickly as they should, quite annoying.
I changed the throttle pedal in case it was the potentiometer therein that was the problem, but made no difference.
Just wondering if anyone has experienced this and managed to find the source of the problem?
Grateful for any advice as always, many thanks.
Pete

[metalworker0]

You installed another pump ..i believe you have to learn or code it in ..did you do that.

Otherwise all the answers on the net point to a "clutch switch" if that is fitted..the clutch switch lets PCM know you've dipped the clutch, so it can make small changes to the fueling - something to do with anti-stall.
I don't know if its fitted. All cruise control models have the switch

all the best.mark

[painter4]

Hi Gents,

I have a 2011 Transit Connect 1.8tdci , been a bit of a project this year, pretty much finished now and took it for a road test a few days ago.
Drives nice except for one thing, when changing up through the gears it seems to have rev hang, when taking foot off the gas to change gear the revs don't drop off as quickly as they should, quite annoying.
I changed the throttle pedal in case it was the potentiometer therein that was the problem, but made no difference.
Just wondering if anyone has experienced this and managed to find the source of the problem?
Grateful for any advice as always, many thanks.
Pete

Had the same problem, also 2011 connect... i also swapped the pedal for
A brand new one from ford , luckily it sorted it for me ..

[pierresmith]

Thanks Mark, I have ordered a clutch switch and will try it, I bench tested the old one and it seemed ok but you never know, worth a shot.
I just had a thought ( sometimes my best thinking happens in the bath !) when I had the front end up on jack stands a few weeks ago and started the engine up, the front wheels started turning even though the gearbox was in neutral, so some sort of drive was being transmitted from flywheel into the transmission even though gear not engaged.
Could it be that the reverse is happening, when I drive the vehicle is drive being transmitted from the transmission back to the flywheel and keeping the revs up, preventing them from dropping as quickly as they should?
The engine runs great at idle and when revved it drops quickly - different story when the vehicle is in motion.
Let me know what you think, if there is some logic here then I can see the future - gearbox back out to change the clutch and concentric slave cylinder, I knew I should have done that whilst it was on the bench!!
Cheers,
Pete

[metalworker0]

That's just the oil film dragging the gears, as they are in constant mesh ,..when put in neutral, synchros within the gears are so close to each other, that the oil film drags gears along. you should be able to stop the wheel turning with your hands, probably gets less drag as the oil warms up. almost impossible to explain unless i had a gearbox apart in front of you/

There are plenty of vids on youtube the explain how the sychromesh gear box works but non showing oil drag.

I don't think this well known effect will cause your engine to hang on the revs. unless someone had put thick gear oil in it.

btw ..i did not say go out and buy a clutch switch ..i said look into it and test it.

all the best.mark

[pierresmith]

ok understood, thanks. I might drain the gearbox oil and replace it with some good stuff just in case it's a contributory factor.
I'll let you know when I finally track the issue down, always get there eventually.....

[pierresmith]

Just a quick update.
Took the van for a spin today, and I noticed that if I operated the clutch very quickly - (ie stamping on it pretty much!) - that I had no rev hang.
So I guess my problem is clutch related, ie the flywheel is not disengaging quickly enough when I operate the clutch pedal normally.
I'll try bleeding it again to see if there is any air trapped in the system, if not I suppose it's gearbox back out to fit new clutch and slave cylinder....maybe slave cylinder is not working 100%.
Hey ho, good job I enjoy being on the spanners.........

[metalworker0]

Yeah, let us know what you find .

all the best.mark