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Different IMRC problem


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I am having trouble diagnosing

 

my IMRC problem. About 10 seconds after start the secondaries are opening. They close with the engine off. With the key in the

 

run position and the engine off they stay closed. I tried to look at the open/close signal coming from the computer. I don’t

 

see one. Is it an open collector output from the computer? If the computer knows the box is open will it send the signal

 

anyway? Right now my suspicion is the IMRC box is malfunctioning and opening on its own. All the mechanical aspects are clean

 

and operate smooth and free. Thanks in advance!

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I would like to

 

"see" the computer try and open this thing at ~4000 rpm. This way I am sure its the IMRC box. I would hate to spent

 

$100 on the wrong part. You are pretty sure its the IMRC box itself? Ever seen this particular symptom? I don't like

 

swapping parts without troubleshooting.

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I would like to "see" the computer try and open this thing at

 

~4000 rpm. This way I am sure its the IMRC box. I would hate to spent $100 on the wrong part. You are pretty sure its the

 

IMRC box itself? Ever seen this particular symptom? I don't  like swapping parts without troubleshooting.

 

/>

 

Over the years the circuit

 

board wears from heat and use. There is a Black/Red stripe wire that the PCM grounds to open the IMRC. You can unplug the IMRC

 

connector while the engine is running (while it is holding it open) and check for ground (using a multimeter) on that wire to

 

see if it's the computer or IMRC itself.No ground on that wire, not the computer/wiring.... If Ground, you have other

 

issues.

 

-Dom

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OK, here is what I found:

 

/>

>The black/red wire is not shorted to grd B) .

 

>key on engine off the bk/rd wire

 

has 12V on it.

 

>key on engine on the bk/rd wire is 0V.

 

>At no time does the bk/rd wire ever go to

 

ground.

 

I tried to "see" some kind of transition at the bk/rd wire crossing the ~4000 RPM point. The

 

voltage never switched and the continuity to ground never switched. Help :blink:

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