Another High Idle thread...sorry.

[agood]

I just replaced the head gasket on my 90 300SEL, and now the idle is way too high. When 1st started it runs above 3000 RPMs. If I pull the wires off the ICV, the idle drops to about 1500. But never goes below that...if I plug the ICV back in...nothing changes, it stays at 1500, but if I turn off the car, it goes back to 3000 again until I unplug the ICV.
I have been over the intake with a fine tooth comb, and since I just did the head gasket, I know it pretty well.
The car idled fine before the head gasket, just was pumping water into the oil. Oh well, at least the oil is dry now.

Any suggestions will be greatly appreciated, I have search all over and can't find a solution.

[slk230red]

Did you replace the vacuum hoses on both sides going to and from the ICV? If you used the old ones, are they still flexible and securely connected?

[agood]

I did reuse the old ones, but they are flexible and connected. I sprayed them with carb cleaner to see if the idle would change....and it didn't . I would think if there was a leak at the ICV, then the idle would not change when I disconnect the electrical connection on the ICV.

[slk230red]

Did you go back over your throttle linkage to verify that it is at idle?

I had just the opposite problem when I replaced my head gasket, oil in water. When I finished I had a low idle problem. I found the problem by checking the DTC codes and it pointed to the Air Flow Sensor Potentiometer. It turned out that I had inadvertently reversed the Air Flow Sensor Potentiometer plug and the Throttle Position plug. They are identical and next to each other. So after swapping them back to the correct components, the idle returned to normal.

Good luck finding your problem.