328i "rev float" when changing gear?

[clarkey328is]

Hi guys,
I've had my 328i E36 a few months now and I was wondering if anybody had had this problem before;
When I dip the clutch to change gear, the revs just hang there for a couple of seconds. In lower gears it even seems to rev a bit more. I've had a search but nothing comes up.
Cheers in advance,
Alex

[Sam_68]

I don't 'do' BMW's, so apologies if it's FBW throttle or anything, but are you sure it's nothing obvious like a sticky throttle cable?

Obviously if the throttle is 'hanging' (or releasing sluggishly due to cable or pedal drag), then the revs will increase when you depress the clutch, 'cos you're taking the load off the engine.

[rev-erend]

Heavy flywheel ..

[clarkey328is]

It's a cable throttle and it seems to be operating correctly, I suppose a bit of lube wouldn't do any harm. I'll give it a go, thanks.
Reverend- My old 318is also had a very heavy flywheel but I never noticed any rev float. Do you think this is normal for a 328i then?

[Mr2Mike]

Virtually all modern cars seem to do this, certainly anything with electronic throttles that I have driven. Really annoying.

[clarkey328is]

Mr2Mike said:

Virtually all modern cars seem to do this, certainly anything with electronic throttles that I have driven. Really annoying.

It's a 1995 with a cable throttle.

[Gaspode]

I don't know if this is going to be helpful at all, but:

There has been a bit of discussion in Morgan circles about this effect with the Zetec-engined cars. Apparently with Zetec engines the problem is caused by the throttle position sensor not giving a low enough voltage for the ECU to recognise that it's properly shut. The ECU is set to recognise anything below 0.7V as being shut, but the lowest available voltage from the TPS is set by the relationship between TPS body which has got the rheostat in it and the throttle body itself. Often this never gets below 0.8V, hence the ECU failing to shut down the revs properly.

The fix is to carefully drill out the mounting holes on the TPS sensor so it can be twisted slightly to give a lower voltage reading when the throttle is actually shut.

The full documentation on this is in our wiki, here: http://tinyurl.com/2uehg8g

[GPT]

I may be off the mark here but could it be due to the Clutch Delay Valve (CDV) fitted to these cars?

Removing the valve is a popular mod.

[andygtt]

my E36 M3 started doing this about a year ago, checked the thottle linkang and throttle bodies etc and just couldnt work it out, it felt like the ecu had suddenly decided to blip it on dipping the clutch.

I eventually found it was the under dash carpet had dropped slightly and was fouling the top of the clutch when depressed, resucuring it (or ripping it out as mine is a track car) cured it 100%.
It didn't feel like fouling when you drove the car or depressed the clutch just held revs in high gears or slightly raised the revs in low gears for a second or two before dropping to normal.

[y282]

delete CDV anyway, makes a big difference. have you checked for gaps in the intake after the AFM? any splits, etc, unmetered air getting in could be a cause.