Questions and Answers

BMW Idle Fluctuates Q. Hi, This is George. Here is the car: 1993 BMW 525i, 2.5 liter, Automatic Transmission. Put new K&N air filter. Put new fuel filter. Put new spark plugs. I read some of the Bentley's manual on the rough idling that I have been seeing. It used to roughly idle on stop lights, went to a mechanic that said he changed the Idle speed control valve but I do not think so since it looks old and scratched.

Lately it has been roughly idling on the Park setting only and not in traffic. After reading the Bentley book, I decided to clean the throttle body. I used a dry cotton cloth, it is a lot better but still idles up and down a little on the "P" setting and sometimes it reaches the idle speed sooner that others and sometimes it does not.

I am still worried if I should have cleaned the throttle body with carburetor cleaner instead and when I can get to the Idle valve that sits under the intake manifold by removing the air intake piping. Could it be the idle speed valve going bad? With A/C it still maintains the right speed even in traffic, it is just at the "P" setting that I see the variation. It used to be the other way around before changing the spark plugs that this guy should have replaced.

I ran into a crook of a mechanic that would not change anything that is hidden.

Any thoughts, please advise.
George

A. I hope you had the fuel hose recall done on your car. From the recall bulletin number 94V066:

Feed fuel hoses can harden and "set" over time, allowing a seepage of fuel at the connection between the hose and the engine fitting. The clamp used to hold the hose to the fitting is unable to compensate for the hardening of the feed fuel hose.Fuel seepage between the feed fuel hose and the engine fitting can result in free fuel in the engine compartment, which could result in a fire when exposed to a source of ignition.

Okay, as far as the idle speed fluctuation, I would check to make sure the right spark plugs were used in the replacement. The only spark plugs that should be used are:

Production Date	Spark Plug
Up to 9/91	NGK BCPR7ER Bosch F03DAR Bosch F04DAR
From 9/91 to 9/92	Bosch F04DAR
From 9/92	NGK BKR6EK Bosch F8LDCR

You got the source of the problem correct, you just didn't go far enough. You can use carburetor cleaner on the ISCV and throttle chamber, in fact it is recommended.

I don't think the ISCV is bad, just gummed up. I would give it that real good cleaning and that should take care of it.

Additional Information provided courtesy of ALLDATA