Slow return to idle after cleaning throttle body

[Gareth Randall]

My 2003 Ford Escape 2.0L (UK model, actually badged as the Maverick over here) has had a sticky throttle pedal since I got it, and simple diagnosis made it clear that it was the plate inside the throttle body that was causing the problem. I finally got around to cleaning the throttle body today. I did it the proper way, by removing it from the engine.

The stickiness is gone, but now I’ve got a much slower return to idle. If I blip the throttle at idle, it will take nearly three seconds to normalize. I didn’t touch the IAC motor at all during the operation, it’s not attached to the throttle body, but the TPS is. I’m getting no fault codes.

I think I read somewhere that after cleaning a gunked-up throttle body, you might need to reset the engine ECU so that it can relearn the idle parameters from the newly-cleaned TB. Does that sound like it might be a possibility?

Also, once I’d cleaned off the deposits that had built up in the throttle body, I noticed that the plate doesn’t form a perfect seal – you can see a tiny crack of light between the part of the plate that pivots upwards, and the bore. Is this actually normal for throttle bodies? It doesn’t seem to be affecting the idle speed (once it’s normalized).

Topic

[Dave Tidman]

You need to do a relearn. See if this helps:

http://ricksfreeautorepairadvice.com/ford-throttle-body-relearn-procedure/

[Gareth Randall]

Thanks for that, but unfortunately it’s for the electronic throttle bodies and mine is mechanical.

[none]

Ford’s IAC valves themselves are pretty reliable pattern failure parts. They get sticky too and about the only thing you can usually do with them is replace them. It’s possible that you’ve had one problem masking another all this time.

**EDIT**

The down and dirty method to test them is to simply tap on them with a screw driver. In your case, you’ve got the luck of having a mechanical throttle so you can snap the throttle under the hood a few times. Look for that slow idle return and tap the IAC. If you can hear idle dropping faster or idle reacting at all to the taps, you’ve isolated a bad IAC.

Give it a shot, see what happens, and keep us posted.

[Author]

Replies