My engine revs at about 1000rpm (M44 engine)

[Vince70]

Hi I've got a bit of a problem with both my Z3 and my E36 which both have the M44 twin cam 4 pot engines in that the revs seem to stick at around a 1000 rpm and then a couple of seconds later the revs will drop to about 800 rpm rather than just dropping to 750 rpm straight away.

It's quite frustrating especially when sitting in stop start traffic and I can't find any noticeable air leaks on either car and wondered if anyone had experience of this problem and could give me a few pointers...

[BladeRunner919]

Are you completely stationary? The revs stay a bit higher if the car is in neutral but still moving, and then drop back once the car stops - I assume it's to stop the engine bogging down if you then put it into gear to keep moving.

[Vince70]

Yes I'm completely stationary and I find the real problem is when pulling away as the car is still revving quite high..
But it could be something I'm doing wrong as its the same on both of my cars but I've never had the problem on any other car I've owned..
I was thinking of disconnecting the MAF to see what happens..

[Del]

Mine's always done the same - I've checked, cleaned and changed most things and it's just the same - in fact mine has always fallen back to around 900rpm at idle. Older BMW technicians will confirm that that the M44 engine was known for a "harsh/lumpy idle" and many had a slight timing change automatically done at early main dealer services - a result of which was a slightly higher idle rpm.

[littlefeller]

its connected to the speed sensor, mine does the same, if I roll along in neutral the revs are higher, then they fall once the car has stopped. mine got stuck once and just stayed at 1000rpm even if I wasn't moving, a couple of days later it cleared it self, maybe a sticking valve of some kind in the intake (idle control valve)

[Vince70]

Thanks for the help I did clean up the idle control valve today on the E36 as it seems more of a problem than on the Z3 and it didn't make any difference..
But I noticed the car had a very rough loud sounding exhaust when I got out the car and put my hand over the end of the exhaust and noticed that although the exhaust is relatively newish item it had a couple of holes in both of boxes so I ordered this..
http://www.ebay.co.uk/ulk/itm/181376825994
I ordered the same make one for my Z3 and these exhausts are great quality so I'm hoping it will help with the idle problems..

[littlefeller]

i have fitted one of these this weekend, bargain

[Vince70]

I now have the same make exhausts on both my Z3 and E36 but have to turn the stereo up now to cover the noise as both cars sound like council estate scoobies lol.
But I still have the idle problem with the car revving too high (1100 rpm on average) and have now cleaned out the idle control valve and also I tried disconnecting the MAF but that also didn't make any difference so the next step is to buy a throttle position sensor so it's fingers crossed that sorts out the problem as the car is getting horrible to drive in stop start traffic..

[Southernboy]

Hi Vince
I take it your car is fitted with a bowden cable from the pedal to the throttle ?? That would mean you can make a small adjustment to the cable at the throttle. There should be a screw in attachment / fitting there. If it has such a fitting, you should be able to screw it inwards to release the tension on the bowden cable and that should / may drop the rpm. You might have a look at the cable too. If it is "old" it may be that the return spring at the throttle can no longer pull it back fully. The cable may have one tiny wire which has broken inside the cable housing / sleeve and it's catching at the critical point, or the cable may have one point in it's route where it takes a fairly tight bend and it's possible it might be sticking there. You could detach the cable at the pedal and throttle and manually slide it in and out to feel if it moves freely within the cable sleeve. If it' feels tight, perhaps try dripping some fine oil (WD40 or the like) into the cable sleeve and working it back and forth. Also, check the pedal fitting to the floor of the car... it clips into position with a plastic clip which will wear over time. I replaced my 2.8 pedal some years ago when I found it was worn and sticking albeit erratically. The pedal wasn't returning fully on release, and the motor would revs wouldn't drop until I stuck my foot under the pedal and pulled it back. Damn fiddly to get the pedal out though. You could also try some light grease at the pedal hinge point.
I haven't read through the entire post, so if I'm repeating stuff you've already covered...apologies...

[Vince70]

I took the throttle body off yesterday on the E36 and gave it a good soaking in some carb cleaner and polished the innards with some autosol and also gave the idle control valve another good clean while I was at it..

I also disconnected the throttle cable and ran the engine without it connected and when the car revs up the revs seem to still stick at around 1000 to 1200 rpm but at least I now know it's not that.

I do have a throttle position sensor on order so I'm hoping that will cure the issue and I might have a play with the throttle position screw to see if I can someway sort the problem..

It didn't help yesterday taking the z3 out for a spin as its mechanically the same car and drives so much better...