Expert: Dan Roberts - 9/3/2006

Question
Hello Dan.

I recently purchased a 1989 525i. The car recently turned 200,000 miles, but the previous owner was obsessive about oil changes and took very good care of the car.

The car was running wonderfully until this morning. When I started the engine, the idle was very erratic (500 rpm to 1500 rpm, back down to 500 rpm then up to 2000 rpm). When I pushed on the accelerator, I could hear and feel the engine was "choppy" (for lack of a better word). Again, while revving the engine, the rpms were erratic. I tried taking it for a drive, and the car jerked and bounced. Basically, the car had difficulty accelerating. I couldn't even make it down my street :( It did NOT die on me, but it was very clear I would not be able to go anywhere.

The car has a brand new catalytic converter, new spark plugs, and a new fuel pump. This seems like a fuel/air flow issue? Any thoughts? Your response would be greatly appreciated.

Thank you!
Maria  

Answer
Sounds like you landed a good car. Mileage on that car and motor is not a scary number. Just make sure the timing belt has been done, that is an interference motor. As far as your idle problem it sounds like the idle valve. If you look at the top center of the intake manifold right where the throttle body and air intake tube meet the manifold there is a small tube the branches off the air intake tube and bypasses the throttle body. You will see a large metal solenoid with a 2 wire connector attached to it. The solenoid should be in the shape of a "T". This is the idle valve. While the engine is idling irraticaly tap on it with a ball pein hammer, not very hard but just enough to free the butterfly inside. That should clear up the idle. If it does take it off and clean it with carb/choke cleaned available from any auto parts store. If cleaning it works congrats, if not you need a new one because the solenoid is dead. Good luck.