Help me stay away from the stealer!!

[scooterkail]

Problem: Upon cold start, engine idle hunts from about 500 rpm to 1200 rpm. It eventually oscillates out of control and dies. This condition persist until the engine reaches 190 degrees. The engine then idles perfect and runs like new. Car's a 1995, 325ic.

Original diagnosis based on reading 100’s of post on several forums was a dirty/sticking or bad ICV. Seems like every BMW ever made has at sometime had idle problems!!

To date I have completed the following:

Parts that have been replaced:
Idle Control Valve
Hose from ICV to air boot
Hose connector/o-ring from ICV to intake
All Vacuum hoses
Intake Manifold gaskets
Cleaned/Checked injectors replaced seals and pintel caps
Mass Air Flow Sensor boot
Breather hose o-ring at valve cover
Fuel Filter
Air Filter
Water pump (died while in shop)
Thermostat (replaced just because)

Sensors and other items checked based on Bentley service manual:
Throttle position sensor - resistance values within spec
Engine coolant temp. - resistance values within spec from 20 to 170 degrees
Intake Air temperature - resistance values within spec from 20 to 170 degrees
Verified wire continuity from ICV,TPS and ECT to DME.
Voltage from DME to TPS and ECT verified
Ignition coils resistance check, ok
Injector resistance check, ok
Swapped out Vanos solenoid, power checked ok


Could it be the DME?? Any other suggestions?
: : I give up!! : :

[///M Power]

Have you checked your O2 sensor?

[drz]

My car has done that for years. I absolutely don't care. I know for sure I need one new o2 sensor and a new catalytic converter, if that is any help.

[scooterkail]

Two other items to add:
The computer does not throw any codes during the rough idle.
The engine runs very very rich during the rough idle.
Replaced o2 sensor about 2500 miles ago.
Don't know how to check the cats!

[///M Power]

Check air filter and other intake components is all I could recommend.

[Furious]

i think it could also be o2 or cat related, it seems that once the catylist and the o2 reach near optimal temperatures they work the way they are suppose to but prior to that its not working as it should

[BMWJNKY]

People please stop shotguning a CAT at your cars, unless it is broken up and clogged inside it has nothing to do with how the car will idle/run.

The surging idle to me sounds like the VANOS unit may be sticking or worn out causing the cam timing to be off. I would run the car for about 15 min with a bottle of Liqui Molly Engine Clean in the oil then do an oil and filter change and see if it runs any better. If that doesn't help I would try and find an independent BMW shop that knows the older cars well. The problem with taking your car to the dealer is about 60-80% of the techs they have working there only know the late model cars since 90% of dealer work is warranty.

[jetpacman]

My 318 E36 was doing exactly the same thing. I've heard a hissing sound for a while and finally shelled out the cash to have it fixed. The exhaust manifold had torn off right where the branches in the exhaust meet the flange. As soon as it was fixed the oscillating rpm went away.

I guess there wasn't proper flow past the O2 sensor which in turn resulted in the wrong values being fed back to the control system resulting in the oscillation of the rpm as the it tried to return to the set point. At least thats what I think in terms of general control systems.