I have been tracing down a low idle on an 89, 740 wagon 189k+-. This is the 2.4 jettronic ignition by Bosh. The dealer diagnosed the AMM, which it was'ent (I got a nice new one and a valuable lesson). I cleaned the throttle body twice now, put a new flame trap on, old one wasent bad.

I took the IAC off, it was pretty clean, but the trap door only opens about 1/8" or only a 1/4 of the possible 1/2" opening.

I put it back on the car and observed during cranking. It closes tight for the start, and then opens that 1/8". I could not force it further with a screw driver, and this version (two wire plug) is not servicable unlike the prior years.

Should it open all the way up?

Thanks for the tips.

Eric

Eric,

I'm pretty certain I've never had the opportunity to play with a 2-wire IAC, so with that disclaimer and a grain or two of salt, I'll offer this: something broke off and lodged in the brush and commutator end of the valve preventing it from turning further.

I'd expect it to rotate 270 degrees, opening fully. Doesn't make sense to me for it to be designed any other way. By not opening fully it would certainly restrict your ECU from normalizing your idle rpm.

If I'm wrong I will eat my words and learn something, hopefully not at your expense, but if you can loosen a clamp, and maybe use a screwdriver to carefully admit a bit of additional air toward the manifold, an increased rpm might convince us both.

Seems I recall one rest position of the 3-wire IAC is past the closed point and about 1/8" open, but against the spring on the two-wire unit it should open fully. Pretty vague recollection here-- I hope for some more responses.
--
Art Benstein near Baltimore

I am in the process of figuring out why my car idles poorly and has low power.

I am going to replace the IAC with a pull. Is the valve in there supposed to close on it's own, when I turn it with a screw driver, it just holds the position I set it to.

Can I use WD-40 in there to clean it??

Thanks!