Idling Problems

Hi all

I am once again bringing up the topic of idling problems on my car which I cannot seem to fix (87 320i BMW with L-Jetronic Managment). I still cannot find this damn Idle Control Valve anywhere. I practically stripped down the whole top of the engine yesterday to no result. Is it possible that the car can some how be set up to run without an ICV? I have found a sort of valve that is under the Intake Manifold that is silver and about 7" long. It has 4 pipes on it which currently have coolant running through 2 of them and air from the 'rubber boot' running through the other 2 and it has no electrical connectors. I have very intrestingly found a long wire with 2 connectors on it just hanging in the engine and I cannot see what they come from. Could they come from a ICV that used to be there? Can anyone give me a couple of places I can try looking for the ICV on the engine?

And having read a couple of other threads, people are talking about a 'Mixture Adjustment Screw" on the body of the Air Flow Meter. The only screw I can find is on the Metal Part of the AFM and it requires an allen key to turn it. Is this the adjustment screw and would it fix my idling problem?

By the way, the problem Iam still having is that the car will idle at about 500RPM when cold and then steadily rise to about 1800RPM when warm. It used to surge at idle from about 600RPM to 850RPM. But this has now been replaced by the annoying sound of a car idling at 1800RPM! I have checked all of the Vacuum tubes and there are no leaks.

I finally bit the bullet and took it to my local BMW dealer who told me, and I quote here "I dont know how you're car is idling"!!! I am correct in assuming these guys built the car? There are no other dealerships called BMW hey???

I am really holding on by my last string here. I have a nice big 20 pound hammer which is going to meet my car engine if I cannot figure this out. Where do you go if the guys that built the car have no idea???

Regards

Beemaboy

There is nothing there except varous pipes that go off in all directions with only one going to the silver valve thing that I mentioned above. I think this design could be attributed to the fact that it is a vacuum engine. This silver valve thing is called an Air Slide Valve and it is the only thing I can thing of that can be controlling the idling, but there is no way to adjust it. The Haynes manual I have goes on about adjusting the idling by a screw on the throttle housing, but I cannot see any screw on there. Does anybody have any idea what they are talking about?

Thanks

I think Madrab is in the right direction! What is your AFM like and how many miles has your car done? Are there any splits in the intake trunking or in the intake system? Sounds like an air leak to me, or am I missing something?
I would try and find the ICV before you adjust the settings, as once you find the ICV or replace/fit it, your idle will be way out again.

I think you may have found you problem BB by the fact that the tests you did have given the desired results. I don't belive the valve is adjustable, just works off the warming coolant. BTW, German and Swedish have an Auxiliary Air slide valve for the pre88 320i for £26 as against £326 which seems a little extravagant?? Tampered with? What, with spraying it with carb cleaner? That's a bit excessive but if it's BMW then I'm not surprised.

The other point about the actual idle, did you look for where the cable connects to the Throttle body, is there a screw adjustment on the cable end for the tick over as there does seem to be on these diagrams? Not sure if you are left or right hand drive? http://www.realoem.com/bmw/partgrp.do?model=1132&mospid= 47257&prod=19870100&hg=35&fg=10

If it does return to 750rpm then I would say that the adjustments are fine and something is getting sticky now and again which causes the higher idle sometimes. Does the tick over return to normal if you pull the accelerator up to normal rest position, if so the cable's at fault. The ECU will have an optimum idle setting but if it is getting wrong info from say the throttle position sensor then it will compensate. You may also have a sticky flow meter, some fault checking to find the culprit required. First thing, IMO would be a new valve though.

Rob

Hi

To address Madrab's point about the price and being tampered with, I was actually talking about the AirFlow Meter not the Air Slide Valve. Someone has removed the black cover ontop of the meter and then resealed it with glue. This is what I meant by tampering.

To also get to what you said about the ECU overcompensating for incorrect readings from a sensor. How hard is it to adjust the Throttle Switch. I looks to me like there is a screw on the bottom of the throttle housing and a small plate for the switch to move back and forth. Must I just move the switch till I get the correct idle when the car is warm? I have checked the accelerator cable and it is not holding the throttle open and if anything there is probably a little too much free play on it which I cannot adjust as the screw is rusted solid. Funny thing about the Air Slide Valve is that it was replaced not 5000miles ago. I cannot imagine that the failure rate is this high? Do they really get gunged up that quickly? I have tried putting a squirt of carb cleaner in the valve and it seems to have dropped the warm idling down to about 1200RPM, which is still high but definately better. Risking serous burns, I managed to get my hands into the engine bay after driving about 20miles to see what the valve looked like (eg:open or closed). It seems to be just slighly open, and by slightly I mean about 3mm. Is this enough to really screw up the warm idling? And I forgot to mention before, it is very hard to start when warm unless I block up the air pipe, after which it starts perfectly.

To get to what Starfury is saying about his 1999 328i. It sounds strange that such a new car would suffer the same sort of problem. You would have thought BMW would have found a full proof fix for this, obvously common problem? 

Thanks

BeemaBoy

Just had the coolant alert on when I started her this morning for about a minute then it went out. (Whilst I was looking up the light in the manual)
Reckons I need  coolant top up with that light on, but am I right in assuming if you need a top up then you must have  a leak somewhere?

Well the 4 or 5 times I started the engine since its not come on so you may be right.
What I'd like is for a BMW specialist to give it the once over as I am a new owner of BMW's and worried that there is something wrong with the car all the time. Dodgy idle from cold but fine when warm, hot days cause problems with central locking but fine after cooled down and on cold days, rattling coming from underneath car at certain RPM even when stationary (think its exhaust heatshield), brakes squeaking like a mofo but only at slow speeds and when pushing medium pressure (light and heavy pressure dont squeek).
But I can't afford to take it to BMW lol.... Any specialist on the forums require some IT technical help and fancy a trade free time?