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Iac valve issue

Old 10-29-2016, 11:14 PM
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Default Iac valve issue

Hey, I'm new here I have an 2002 jeep grand cherokee Laredo 4.0l with a few bolt ons I have a new 62mm throttle body, 4 hole fuel injectors, and
k&n cold air intake. Recently after the jeep warms up.and the idle air control valve closes and the jeep idles down I can give it gas and the iac opens back up and the jeep revs up with very little gas. I replaced both the iac ,throttle position sensor, and crank sensor. When I reset the battery the jeep runs fine for a week or less and than acts up again. Also runs back to normal after unplugging the iac and plugging it back in.. I'm stumped any help would be awesome. Thank you
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Old 10-31-2016, 12:40 PM
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My 88 had similar IAC problems. Mine would stick on occasion and I couldnt get it to Idle less than 3.5K
Took out the IAC and cleaned it well with some brake cleaner and I havent had any issues since. I heard from a buddy of mine that if you turn your key to "ON" then back to the "Lock" 3 times the IAC resets. Never got around to trying the reset thing so Im not sure if it works, but its worth a shot
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Old 10-31-2016, 01:15 PM
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Thank you for your response it's all new parts including the throttle body so it's all clean.
I'll try the reset today thank u again
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Old 10-31-2016, 01:17 PM
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. I don't think the iac value is the problem. I ohm all three iac values and they all read 52. Here is another way to explain what's happening everytime i give it Gas the iac opens up full and let's alot of air in, causing the idle and power to increase.when I let off the Gas it stays reved up till the iac closes. When I unplug the battery to reset the computer it'll run ok for a few days. Found unplugging the iac for a short time and plugging it back in would also bring it back to normal for a bit.
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Old 10-31-2016, 02:36 PM
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Did all this happen before you put on the new throttle body? I'm thinking it might be something to do with the mixture calibration with the larger throttle body or a MAP sensor malfunction. Something is not allowing the manifold vacuum to return to an idle setting quickly enough for the IAC to recognize a closed throttle. I can't understand why the IAC is opening with the throttle plate. It's only function is to bleed air to establish an idle speed setting.
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Old 10-31-2016, 02:49 PM
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It happend before the new throttle body but not as often. I'm thinking it cold be the coolent temp senor or something telling the pcm the engine is still not up to idling temp. Not sure tho. I have a scanner and the map psi is ill have to check again but I think I recall 5 at idle thank u for your help
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Old 11-01-2016, 06:03 PM
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Originally Posted by azxjtrooper View Post
My 88 had similar IAC problems. Mine would stick on occasion and I couldnt get it to Idle less than 3.5K
Took out the IAC and cleaned it well with some brake cleaner and I havent had any issues since. I heard from a buddy of mine that if you turn your key to "ON" then back to the "Lock" 3 times the IAC resets. Never got around to trying the reset thing so Im not sure if it works, but its worth a shot
I did the reset thing u suggested and it seemed to work jeep ran good today would be awesome if it's fixed haha seems to easy tho. To good to be true. But thank u!
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Old 11-02-2016, 07:44 PM
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It acts almost like the wires are crossed or there's an electrical defect in the harness or a connector/crimp? Next time it happens, and from the sound of things it will, break-out the voltmeter and noodle-around the wiring/schematics. Good luck and remember to let us know...
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Old 11-02-2016, 08:16 PM
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Originally Posted by Cherryokee View Post
It acts almost like the wires are crossed or there's an electrical defect in the harness or a connector/crimp? Next time it happens, and from the sound of things it will, break-out the voltmeter and noodle-around the wiring/schematics. Good luck and remember to let us know...
OK I'll let you guys know it's day 2 and has been running good
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