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Old 09-19-2017, 02:46 AM   #1
zedjr10
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Is my IACV Faulty?

I got a 92 ex coupe. When i disconnect my IACV while car is warm the idle doesn't drop like it is supposed to. It will drop to about 650 rpms when i turn on my AC. Is my IACV faulty. In the DIY it doesn't mention to even turn on your AC. It should drop as soon as you disconnect it. I have checked if it was dirty and it wasn't(was cleaned 8 months ago). I am doing this in an attempt to set my baseline idle. According to the DIY for doing this my idle should drop to 600 rpms. It doesn't drop at all really. Maybe tops 30rpms. So am wondering if it is faulty. Anyone?

[edit]I thought about this a little last night and i think that the plunger must be stuck open a bit and hence why it never adjusts when it is unplugged or plugged back in. Maybe when i cleaned it some deposits got to where it won't fully close. What yall think?[edit]

Last edited by zedjr10; 09-19-2017 at 06:15 PM.
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Old 09-21-2017, 06:04 PM   #2
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Anyone? Anyone?
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Old 10-02-2017, 08:29 PM   #3
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Old 10-02-2017, 11:02 PM   #4
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With the engine warm and the IACV disconnected, the engine speed should be 550 +/- 50 rpm. Can you adjust the idle down to 550? With the IACV connector installed, does the engine idle correctly at 700 rpm (with no load), about 770 rpm (with electrical load)?

Note: The first big tick mark above zero on the tach is 500 rpm.
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Old 10-03-2017, 06:17 AM   #5
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Quote:
Originally Posted by fleetw00d View Post
With the engine warm and the IACV disconnected, the engine speed should be 550 +/- 50 rpm. Can you adjust the idle down to 550? With the IACV connector installed, does the engine idle correctly at 700 rpm (with no load), about 770 rpm (with electrical load)?

Note: The first big tick mark above zero on the tach is 500 rpm.
My idle screw goes down no farther and no i can't get idle to 550. It only drops to 650 when i disconnect iacv and turn on ac. I have checked for vacuum leaks and can't find any. It normally idles at 800 to 820. I do have a replacement IACV from junkyard. My first concern is my IACV might be faulty as idle doesn't drop at all when disconnected. Only when disconnected and then i turn on AC. I was also thinking the plunger on iacv might be slightly open or maybe it has alot of gunk in those small coolant lines. Otherwise the iacv seems to work fine under normal operation. It just got cold and now it is harder to start when it sits overnight. Like 8 or 9 cranks versus 3 before. Any thoughts?
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Old 10-03-2017, 11:06 PM   #6
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How dirty is the throttle body plate? Gunk could be keeping it open a little at full closed. If it looks really dirty, it is probably worth the price of a gasket and o-ring (for the idle screw) to remove it and clean the plate and all passages. Don't expect a JY part to work any better than the one on the car (particularly if it has similar miles). Clean it out real well. Did you use a new gasket when installing it?

If you've removed any of the other valves from the plenum, did you use new gaskets when reinstalling them?

Is there slack in the accelerator cable when the throttle plate is closed all the way? It is supposed to have about .4 inches of slack when the accelerator is released.
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Old 10-04-2017, 02:57 AM   #7
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Quote:
Originally Posted by fleetw00d View Post
How dirty is the throttle body plate? Gunk could be keeping it open a little at full closed. If it looks really dirty, it is probably worth the price of a gasket and o-ring (for the idle screw) to remove it and clean the plate and all passages. Don't expect a JY part to work any better than the one on the car (particularly if it has similar miles). Clean it out real well. Did you use a new gasket when installing it?

If you've removed any of the other valves from the plenum, did you use new gaskets when reinstalling them?

Is there slack in the accelerator cable when the throttle plate is closed all the way? It is supposed to have about .4 inches of slack when the accelerator is released.
I reused gaskets as they were still pliable but old. I checked for leaks there but none. I will have to order an idle screw o-ring. Didn't see one when i took it out and i also checked for leaks there. The throttle body plate is pretty clean. I did use 2 new gaskets when reinstalling plenum some months ago. I have never disassembled the tb. Just cleaned it while attached. If for some reason my fuel mixture was really rich would my iacv act differently cause of that? I have a rich mixture now i believe, it is possibly a bad tstat or my new o2 sensor isn't working(was ngk brand).
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