car runs extremely rough when warm

[cpandrewschmidt]

Hi all,
I'm having issues with my car running very rough when it gets up to operating temp. I push on gas and it sputters and wants to stall out. I've tried everything I can think of. Car ran OK before I started doing tune up items:

timing belt, water pump, thermostat, belts, valve cover gasket, oil change, plugs, wires, distributor cap.

Things I've checked:
all hoses tight, fuel pump filter clean, cleaned ICV and checked MAF flaps all clean, swapped out fuel pressure regulator, new coolant temp sensor, new o2 sensor.

I don't throw any codes. Does anyone have anything else they think I could try? Thanks!

Andrew

[ST1G]

cleaned ICV

I've seen this cause more issues than it fixes. Did you adjust the screw at all? What year and model is the car?

Sounds like a vacuum issue, or ICV issue.

[cpandrewschmidt]

1991 325i

I didn't adjust any screws in the ICV. Just cleaned it good and put it back in. Cleaning didn't make the problem any better or worse. Car ran the same after i cleaned it. Probably need to do a smoke test. Strange part is it gets worse after running for 5ish minutes. When cold it runs OK.

[AndrewBird]

ICV won't change how the engine runs when you rev it.

Sounds like a vacuum leak somewhere to me. When cold, the ECU richens the mixture, then as it warms up, it leans it back. A vacuum leak creates a lean condition (more un-metered air = lower A/F ratio), so the extra fuel when cold would help, but get worse as it leaned back.

[e30onBBSs]

I'm not sure if this is possible/ ever has happened but can the cold start valve keep firing?