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IMRC Testing on 98 Windstar


psb962
10-23-2004, 03:49 PM
I have codes showing one IMRC stuck open, and the other stuck closed, plus a code for lean running on one side.

My mechanic identified the IMRCs, and I have checking their operation to see whether one or both (or neither) are bad.

I did the vacuum check by connecting a hose and sucking; the front one doesnt hold vacuum well. The linkage moves freely, but I cant suck hard enough to get it to do it by itself. I'll assume that IMRC is bad. The back one opens and closes no problem when I suck to create a vacuum. The linkage is freely moving. Looks good so far.

When I start the engine and leave it at idle the front (bad) moves the linkage most of the way but not all the way. Still bad then. The back opens the linkage all the way; still looking good.

Now the problem; when I slowly raise the revs, the back (good?) IMRC closes at about 1500-2000 rpm, which is allegedly way too low. When I go back to idle it doesnt open again until idle. Question: is my back IMRC operating correctly, or do I have a vacuum, or solenoid issue to explore as well?

Thanks, Peter

12Ounce
10-23-2004, 04:19 PM
You might try removing and plugging the vacuum hose to the known "bad" (leaking) actuator and see if that arrangement changes the way the "good" one works.

psb962
10-23-2004, 05:12 PM
Good suggestion. i removed the 'bad' actuator's hose and plugged it, then started the engine and ran up the revs. I saw no change in the open/close performance of the (good) actuator.

If anyone has the time, please let me know what a serviceable Windstar IMRC behaves like when you rev it up.

12Ounce
10-23-2004, 06:22 PM
I don't know what the exact sequencing is on your model.

In my non-expert opinion, the whole split port input thing is a sham and useless on a minivan application....but the PCM must be made happy or you get those codes. I'd just replace the bad actuator and see if that makes all well.

wiswind
10-23-2004, 07:20 PM
Another thing to check....is how freely the defective side moves.

Just an off chance....that it might be hanging up or has a higher resistance to movement than it should....I have read posts on here about issues with bushings in the linkage....

Another, less likely is an issue with buildup in the intake manifold interfering with the movement of the plates.

From what I have read.....they should open up at about 2900 rpm.
This is an aproximate value...as they are controlled by the intake manifold vacuum.

I agree with what you have already been told.....Worry about getting them both working......then see what happens from there.....

psb962
10-23-2004, 09:31 PM
Both linkages move fully and freely by hand, against the spring resistance. I'm sure the linkages arent the problem.

Looks like I'll get my mechanic to replace the bad one, and run it to see if the codes disappear. If they do, great. If they dont, I'll get him to compare the opening of the remaining old actuator against the new. If there is a significant difference, and the codes still point to an error with that bank, I'll replace that one too.

As these piddling little actuators are $223+ tax EACH, if you can think of something else I need to check first, please enlighten me.....

12Ounce
10-23-2004, 09:35 PM
Some other posters have found aftermarket IMRC actuators on some internet location for about half that.

psb962
10-24-2004, 06:49 PM
I tested the vacuum to the IMRC and found that the vacuum goes to zero at between 1000 - 2000 rpm, and doesnt come back until revs drop to idle. Is this right, or do I have a faulty solenoid?

psb962
11-12-2004, 07:33 PM
Fixed! I bought a front IMRC from FiveStarFord for way less than $223 MSRP, had it fitted, codes cleared, and test drove it. I made sure to really give it some throttle to make sure the IMRCs would cycle under load.

No codes! So whatever my IMRCs are doing, it seems to work fine. Thanks all.

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