Idle Problem (yes, i have searched)

[QuickSilver 0]

Hi guys, i've tried SO hard not to post this, but im at my wits end, its a problem ive encounterd before many times, but seeing as I mostly owned carberetted cars, this was easy to fix, imo.

I start my car, and wham, idle speed VERY high, 1500 to 1800 especially in the cold, after a while of driving, it will drop, first to 1500, after a little more to around 1200 where it will stay, ive assumed it drops due to engine heat warming up (duh)

Im thinking that it should be sitting somewhere between 750 - 850 rpm.????

Anyways,

I am asking what to do? ive read the posts regarding this, and you've listed solutions, but im still VERY new to the bmw's, dont have a manual (yet) and dont know my way away the bimmer engine very well, can anyone offer and help or advice and dumb it down for me? Any help would be hugely appreciated, ive only ever really driven one other fuel injected car and it was for a short time and I never needed to do any work on it, im slowly getting to know the bimmer engine but its a slow process lol,

I have a 1987 p/fl 320i m20 motor.

Any help would be hugely appreciated, thanks guys.

Alex.

Edited June 1, 2007 by QuickSilver

[will 169]

Take a photo of your engine from the driver's side focusing on the intake manifold and one from the passenger side focusing under the intake manifold just in front of the starter. I just want to make sure what setup you have before commenting on possibilities.

Will

[QuickSilver 0]

Thanks heaps! Ill take them tomorrow and post them up in the morning, cheers again!

Ok, heres the photos, it was raining while i was taking them so their a bit rushed and dont know if their of any help, i just posted all 4 i took up anyways, if you need any more info please just let me know, any help is great! thanks heaps!

Edited June 2, 2007 by QuickSilver

[QuickSilver 0]

sorry, fotos added, thought id be smart and edit my old post forgetting it wouldnt bump it along.

[Guest Ken]

sorry, fotos added, thought id be smart and edit my old post forgetting it wouldnt bump it along.

Hi - Will's bound to solve this but in the mean time check the areas I've asterisked in red for leaks and/or cracks. I had similar issues with my 323i that had a cracked inlet elbow.

K.

[will 169]

Ok, pic below I have arrowed your idle valve. It is temp controlled by passing water through it and opens and closes an air duct according to temp of the water. It is inclined to stick or fail if the cooling system is not maintained and cheap antifreeze is used. I would suggest removing it and check if the valve is operating correctly. There are 4 pipes to it, 2 from the cooling system and 2 providing a bypass air flow to increase/decrease the idle. Look through the holes which provide the airflow, you will see a piston with a slot in it. When cold it will be wide open. Put the unit in boiling water and see if it closes almost right up. If it doesn't you can try soaking it in a light penetrating oil for a while and then test it again. If this doesnt work, relplace it.

Check the two air pipes to it, one will go under the manifold to the vent at the top of the rocker cover, this pipe often cracks at the rocker cover and leaks air which will speed up the idle. But check both pipes along their length for cracks etc and replace if cracked.

Also check that the water pipes to the idle valve are free and passing water through them, be careful of the one pipe that is attached to the base of the thermostat housing, the connection there is delicate and you will break it off if not careful. It also corrodes under the pipe so watch this too.

From the other side I have arrowed the idle screw in yellow. Once you have sorted the idle valve, set your idling with this screw. Check all the pipes to it for leaks/cracks.

I have also arrowed the breather from the top of the rocker cover in pink, this is the pipe that often cracks and leaks air, check it carefully.

Try these things first and see how you go. The 327 eater was doing exactly what yours is doing and I found it to be a combination of cracked pipes and a faulty idle valve and coolant pipes that were blocked and didn't allow water to flow through the valve.

Will

[QuickSilver 0]

Thanks so much guys i appreciate it so much you have no idea! ill start with checking everything tomorrow! Thanks again!

Alex

[QuickSilver 0]

So AGES later I finally replaced my idle control valve, if u wish I can post up a pic of my old one, it had blue , silcion/rubber type something hanging out both the water ends... weird also it had started corroding and just generally didnt work... replaced that, and I think the car idles smoother but no lower, it still idles a bit high, there is one crack in a hose which I had to re-use because I dont have another, but which i am getting onto, its the vacuum hose that is NOT connecting to the thermostat housing, the crack is where the jubilee clip sits thats why I wasnt too worried about re-using it... ANYWAY... once I replaced the valve adjusted my idle screw, and its as tight as it can go, however the idle is still too high, could this one crack in the hose be the cause of the high idle???

note that for a little while after I installed the new valve the idle dropped to near normal... but then just did the same thing as usual...

it idles cold at 1.8 and warm at 1.1 ... too high in my books.. any ideas??

Cheers.

[gmccormack 0]

I had a similar problem with my old 323. After 300000+kms, wear in the throttle body shaft/bushes had caused an air leak.

Also, does the rod on the start assist diaphram retract once the engine is running?? It should be pulled out of the way by high manifold vacuum, but if it is leaking or its vacuum hose is leaking or disconnected it will keep the throttle plate from closing properly.

[QuickSilver 0]

it moves in an out when the throttle opens and closes, seems to be working fine, hmmm...

[QuickSilver 0]

update: Idle has been fixed, now idles properly, it turned out to be an air leak in the manifold, but thats all fixed and working now, the ONLY thing not perfect, is the cold idle, it doesent have a good cold idle, and I have to warm up the car (not that I mind) before I go, even with this little problem, the idle is WAY better, I dont mind sitting for a minute or so, now the car seems to be performing a little better, smoother and just generally seems healthier lol,

is it the ICV which controls the cold idle?? ie, as I said I just replaced my old one, so could it be the valve?? Cheers.

Alex.

[joel 0]

Repair Manual here, saves you buying one