1988 635CSi Idling issue

Found multiple vacuum leaks on my E24. Replaced the hoses needed to correct the vacuum leaks I found. Now when I start the car it idles surging from around 500 to 1000 rpm. The ICV seemed fine pulled it out to clean it. Just wanted to know if there was anything else that I should look at before putting the ICV back in.

Try cleaning the air passages connected to the IAC, they're prone to buildups and can be restricting airflow.

Cleaned all portions of the Motronic system with Carb cleaner and rechecke dall the vacuum lines for leaks. Found nothing. Moving on to the O2 sensor not sure when it was last replaced any suggestions for testing the O2 sensor.

Originally Posted by BmrChat

Cleaned all portions of the Motronic system with Carb cleaner and rechecke dall the vacuum lines for leaks. Found nothing. Moving on to the O2 sensor not sure when it was last replaced any suggestions for testing the O2 sensor.

If your not confident it's working properly, replace it. It's a maintenance item and could be part of your problem. You may also want to clean the Air Flow Sensor and confirm it's operating correctly. Consider buying a Bentley BMW 5-Series E28 repair manual because E28's and E24's share alot of components and systems and unfortunately, Bentley doesn't publish an E24 version. It has alot of valuable troubleshooting info. You should be able to find one for less than $50. I've seen a few on Craigslist lately for $25.

Thanks for the help.

Went to replace my O2 sensor but the sensor wouldn't budge and i didn't have time to take the whole exhaust off to do the job. I ended up tapping on the sensor a bit and i guess that did the trick now the car runs great.

Originally Posted by BmrChat

Went to replace my O2 sensor but the sensor wouldn't budge and i didn't have time to take the whole exhaust off to do the job. I ended up tapping on the sensor a bit and i guess that did the trick now the car runs great.

If's it's old and suspect, I'd still plan on replacing it. You may get better luck if you try to remove it when the exhaust is hot, but be very careful and protect yourself from burns, etc.

Its going to have to be torched out. I tried everything penetrating fluid with and without the exhaust being hot.

Originally Posted by BmrChat

Its going to have to be torched out. I tried everything penetrating fluid with and without the exhaust being hot.

I beat mine out with a cold chisel, by hitting it in a manner that would help unscrew it. I also cut off everything above the hexagonal bolt part so I could put a heavy duty impact socket and breaker bar on it. It eventually came out.