High idle speed

I have an 85 M325e. It idles at about 1400 rpm when warm. If I drag the clutch, I can get the idle speed down to normal (700rpm or so). I do put the clutch back to the floor after I do this, and the rpm stays at 700 or so. What is going on?

Hey mate, i just did a threat but i had exactly the same problem, mechanic said he didnt know what it was and it shouldnt be a problem


Yeah Right!
My car now revs at 2,000rpm and well over, it used to rev at over 1,400 and kinda jump from say 1,200 to 1,600. I have noticed that there is a unpluged plug and maybe that could be the problem with the ecu not finding a responding engine or something. The problem is i cant find its jack and it must go back to the mechanic

Idle air control valve. It by-passes the throtel in oder to set a preferable idle speed. The throtel itself is fixed and almost never needs adjustment. Try disconecting it.

The valve reseambles a solenoid or a little electric motor that screws into the throtel. It sometimes needs adjutment. There is a pin inside of it that moves to adjust the idle speed thru 2000-600 RPM. That pin just moves around in the hall to adjust how much air is flowing and is controlled by the computer.

When you first start the engine it should rev to maximum RPM usually 2000 or 1500, and then your rpm should drop gradually and smoothly depending on the engine temp. If this doesnt happen its probably stuck or burnt off.

I discontented the idle speed control solinoud. The idle went up to over 2000rpm, plugged it back in and it came down. The weird thing is that the throatle linkage is free, it seems that the troatle closes all the way, I'm going to clean the throatle butterfly, heard this can be a problem. Although as I stated, I just have to let the clutch out enough to drop the rpm to 700rpm, then push it back in and the rpm stays at 700, without touching the pedal. GO FIGURE! I'll let you know what happens.

Thats strange because disengaging the clutch is supposed to bring RPM down. 700 RPM is good for a 6 and sorta low for a 4 banger. Well now we know that the valve works. Thats a good thing. Usualy a dirty throtel body causes low or rough idle. So that might not be the problem. I would rather take out the valve and see its got some grime on it which could cause it act this way.But before you do that go and check for any disconected, craked, missing, missplaced vacuum hoses.That could be a problem as well.

Generaly if you have such wide range RPM problems.
Its either two things since they both let more air into the engine

1 Vacuum leaks of any kind
Things to look at:
bad crank case vent valve (dirty, stuck)

any vacuum hoses deteriorated

Bad vacuum switches ,say a bad carbon canister switch (either vacuum or electrical switch) could cause this. It also might be affected by the clutch possition.

Stuck open EGR valve.


2 A bad idle control valve ( a bad computer sometimes , but not likely)


There are lotsa things to look at. I dont know if anyone here knows about comon things that could cause this to that engine. What I wrote up there are the things that I look at when approaching such sympotms.


Try disconnecting some vacuum hoses at first. Second, try to disconect them and plug the ports with some plugs. And see how the engine responses (if it stalls, or RPM increases/decreases, or no change at all, etc.)

Hi pbhickey,

It's always best to start with the easiest and the most likely of possibilities ... in this case that means the Idle Control Valve ... VERY common on these.

First, if you just unplug it, it will cause the idle to race. And pulling the idle down with the clutch just tricks it temporarily, probably till you touch the throttle again. Try pulling the IC Valve off the car, then shake it back & forth to see if you can hear it rattle, because there's supposed to be a free slider valve on the inside. If you don't hear anything, it's way gunked up. You can try shooting a bunch of Carb Cleaner down in it to see if it will free up, but by the time it gets to this point it's most likely history and you'll need to junk it and get another. New ones are expensive, 175 dollars or so. A used one that's operative will probably run you 30-35 dollars from a dismantler. Double check yours, but the last 3 digits of the part number should be 695 (?). Most all the "eta" motor cars like yours took the same one, I think (325e, 528e).

The valve works in conjuction with a little green electronic box called the Idle Control Unit. It sits inside the car kind of up behind the glovebox. Sometimes just replacing the valve won't work and you need to replace the Control Unit also. They too, can be had used for probably about the same money.

And incidentally, a vacuum leak on one of these will most likely make the idle lower ... too low, if it's running correctly. Try pulling out the oil dipstick an inch or two with the engine running and you'll get an idea of how it works. But don't think you can use this as a way to lower your idle ... push it back in. If you don't and you drive it around that way, you'll suck engine oil up into the whole intake tract and compound your problems.

And of course make sure all the linkages are clean & lubed as well as the throttle butterfly clean & free and that the Air Flow Meter flap is not sticking (be careful with this one, it's kind of delicate).

Also, check www.BMWe30.net (http://www.BMWe30.net) and click on Articles and Tips for a wealth of info!

Good luck!

Paul (pada)
89 325iA
204k and still looks new!

Hello hello hello
Well I do not know if I fixed it but I did get it to idle at 700-800 all the time. What I did is ajust the throttle blade adjustment screw to bring the speed down. This screw was lose and I could turn it with my fingers, not good! I put some locktite on it it seems to have stayed in place. I can unplug the idle speed control and it does race until I reconnect the plug. The only thing I can see that is not right now is the cold speed is the same as the hot speed, which doesn't scare me as it alway starts and ldles fine hot or cold. Thanks for the help everybody. My next big thing is to find a later engine, to uip the horsepower. Peter