I'm a bit of a novice but learning fast through necessity and poverty....

I have a 1990 E34 518i.

About three months ago the ECU got flooded, totally immersed in water: I dried it out and, surprise surprise, the engine started working OK again. Since that, no serious driveability problems. I've also cleaned all the injectors, changed all filters and fluids, and ,in fact, the engine is more responsive than previously.

There is one problem however. Every time I switch the engine on, whether it be hot or cold, the idle speed drops to about 400 revs and then stabilises at around 800. Once I start driving the idle is pretty steady, if somewhat low. This is not a great problem, only pulling away when first starting up the engine is a bit jumpy.

Now, I am aware that this may be due to the ECU having been damaged but,while the car is still totally driveable, I am reluctant to replace it. I have been told that I should try cleaning the idle control valve but am not sure how to locate this nor the best way to clean it.

Any ideas/suggestions would be gratefully received.