gah rough idle again! - BMW Forum

saltshaker185 · 07-02-2006, 09:01 PM

so i was driving the other day and since its been pretty nice weather ive been able to get by with just the windows down and shit for the most part. This day was HOT though and so i roll the shit up and try the ac, put in the clutch as i roll to a stoplight and the car nearly stalls?? the idle is jumping like a mofo! i keep on the gas a little to steady it out at the stoplight but everytime i let off the gas and have it out of gear its jumping again, i was with my dad and he trys the ac, the idle instantly levels out now?? now when i first start up the car the idle is a little rough and jumpy ever since this has happened... and when i turn on the ac, it dives down REAL low and almost stalls everytime! i dont know what it is as i dont hear any leaks anywhere but i dont really know where i would look... and the ivc is clean as i had the jumping idle before and cleaned it and it drove like a dream until now... when the ac is on and its out of gear and the idle is jumping there is a sound from down near the x brace that souds like a chattering flywheel but i dont know why it would be that, also i noticed in the garage the otherday that it looks like the ac compressor was leaking a little bit when i noticed some green liquid on the floor... didnt think much of it and went on... sorry this isnt in proper paragraph form so i know u all are about to bash me for how i right so if you are then dont bother, i just want help with this!

RexKing86 · 07-02-2006, 09:05 PM

maybe the compressor is just f'ed up?

saltshaker185 · 07-02-2006, 09:22 PM

umm it still blows cold and shit??

RexKing86 · 07-02-2006, 10:05 PM

maybe it needs to be lubed up or something... seems like it works, but is just causing to much effort to turn.

saltshaker185 · 07-02-2006, 10:20 PM

where would i stick my lube can?? haha

RexKing86 · 07-02-2006, 10:50 PM

haha, i know not a technicall answer, maybe something seized in there... im just gonna stop writing in this thread and wait for someone who has encountered this or just knows how to fix it! haha

saltshaker185 · 07-02-2006, 11:02 PM

haha its coool.. thanks for the opinion thuogh... looks like your all over the site tonight???

saltshaker185 · 07-03-2006, 01:24 PM

anyone?

paco1076 · 07-03-2006, 02:53 PM

Well, not a specific answer either. I would have to do some more research, but I know some GM cars have a problem with the idle control motor. If it starts to get weak and you use your a/c, it causes a surging problem in the engine. The idle control motor idles up to assist the motor, but doesn't react fast enough to slow itself back down before over idleing. So it all but shuts the engine off when trying to compensate... Let me do some reading in my manual and I will see what I can find out...

Paco

RexKing86 · 07-03-2006, 09:41 PM

Quote:

Originally Posted by saltshaker185

haha its coool.. thanks for the opinion thuogh... looks like your all over the site tonight???

lol, i do what i can... not that you should talk tho!

saltshaker185 · 07-04-2006, 03:51 PM

rex- haha guilty....

paco- any news on what u were takling about??

anyone else- can anyone at all on this forum help me please? haha

paco1076 · 07-05-2006, 07:24 AM

Not yet, been sick. Will try to read up in the next day or so.

paco1076 · 07-05-2006, 12:26 PM

Ok, was able to do a little reading in the Bentley Service Manual today (get a copy if you don't have one). On page 130-20 it talks about how to test your idle speed control valve. From the symptoms that you have told us, it sounds like this could be your problem. Here is a small section from the book:

Idle control valve, testing:

Idle speed is maintained by the ECM through the idle speed control valve. The idle control function compensates for engine load and engine operating conditions. Idle speed is adaptive through the ECM and no idle speed adjustments can be made.

Before testing the valve, confirm that the throttle position sensor is working correctly.

NOTE -
The tests given below are electrical checks only. They do not check the mechanical operation of the valve. If the valve is suspected of causing poor idle, substituting a known good valve is the best way to check for a mechanical fault.

1) With engine running, check that idle speed control valve is buzzing.
2) Turn on A/C or shift car into drive. Idle speed should remain steady or increase slightly.
3) If valve is not buzzing, or if idle decreases in step 2, stop engine and disconnect harness connector from valve. Check resistance of valve across its terminals. See Fig. 30. Test values are listed below.

Idle Speed Control Valve Resistance Values:
- M50/S50 US engine
Terminals 1 & 2 20 +/- 5 ohms
teminals 2 & 3 20 +/- 5 ohms
teminals 1 & 3 40 +/- 5 ohms

I can't seem to get a copy of fig 30 to post. If I can get that worked out I will. It basically says that when you are looking at the valve as it is mounted in the car, terminal 1 is on the right side and terminal 3 is on the left.

Hope this helps!

Paco

saltshaker185 · 07-05-2006, 04:05 PM

thanks paco, yeah ive got like 3 of those manuals, just never was able to find that info in them thanks for pointing that out though... if it still doesnt fix it ill let you know...

Furious · 07-05-2006, 05:06 PM

oddly enough id get this looked into, maybe there is a problem with the cooling system. the auxilury fan helped level out the bouncy idle? maybe your car is running a bit hot for its liking while at idle (no air passing thought the rad) so i guess what i would first look at is the clutch fan..

while the car is running idle and stopped, open the hood, use something that you can stick into the fan blades (use something comparable to your finger, BUT NOT YOUR FINGER, something maybe rubber like a flipflop lollll) now just see if the clutch fan wants to keep spining or if it stops, it should want to continue spinning.
its not uncommon for the clutch fan to fail, however most people dont know it does until its real hot out, because it will still spin in most cases, but it wont spin like its suppose to.

just a thought