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Low idle when AC is turned off

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Old 04-17-2018, 03:32 PM
yag
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Low idle when AC is turned off

I know this topic has been done to death but I seriously need help. Ever sense I've owned my 04 g coupe mt it idles consistently at 200rpm when the AC is turned off. With the AC on it idles perfectly at 750rpm. It doesn't throw a check engine light. I know the tachometer can't be off because the car gets very shaky like it's going to stall. I've already done the following to try to fix this:
-Reset ECU
-Clean TB/new TB
-Clean MAF/new MAF
-Check hoses, intake and plenum for leaks
-Accelerator Pedal Released Position Learning
-Throttle Valve Closed Position Learning
-Idle Air Volume Learning
If anyone has any suggestions I would love to hear them.
 
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Old 04-17-2018, 04:34 PM
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Do the idle air volume again, did you make sure the engine was up to operating temp when you did it and that the AC was turned OFF ?
 
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Old 04-17-2018, 04:48 PM
yag
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I have done the idle relearn 10-15 times at least. Each time the radio, ac, and headlights are turned off and the car is up to operating temp but the idle stays the same. I will try again later today though.
 
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Old 04-17-2018, 04:51 PM
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And just to verify the reset DOES work yes? You see the light flashing the correct pattern and there doesn't appear to be anything about it that makes you think it DIDNT work correct?
 
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Old 04-17-2018, 04:56 PM
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Yessir check engine light flashes then turns solid then I'd start up the car and wait 20 seconds only to find it drops right back down to 200rpm. I've gone through those instructions a million times now I know it all by heart.
 
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Old 04-17-2018, 05:14 PM
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What happens when you unplug the MAF while the engine is running?

I suspect you have a faulty ECU but you will need Nissan to diagnose that one.
 
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Old 04-20-2018, 05:48 AM
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As cleric suggested you need to take it to a Nissan/Infiniti dealer to diagnose the issue. Definitely update the thread when you find out what the issue is to help others who might run into this problem.
 
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Old 04-20-2018, 12:19 PM
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When I unplugged the maf the car kept running but the idle would jump around 700-1000 rpm. I'll let y'all know if I solve this. My only issue with taking it to the dealership is I have a few breather mods. Cai 75mm tb and plenum spacer. They'll probably blame the idle on that. I know for a fact these arent causing the poor idle because when it was bone stock it idled the exact same if not worse. When I first brought the car to the dealership for an inspection they tried to scam me and they said nothing of the poor idle so I don't trust them. I plan on getting an uprev tune shouldn't that solve the issue sense you can input the idle levels manually?
 
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Old 04-20-2018, 01:24 PM
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If it is an ECU problem then it will just lead to other problems later with the tune. Getting a diagnostic from Nissan will cost $150 or so but then you'll know where the problem lies. Their chain of events for troubleshooting starts with Consult-II recalibration and if it can't pass that or gives wrong values they would be able to immediately declare the ECU was the culprit.

EDIT: I just remembered something, you MUST be in park/neutral with an AT or with the gear shift in the neutral position for the 6MT. If you were in gear with the 6MT it can actually screw up the idle air recalibration for some dumb reason. Same with the AC controller, it needs to be turned OFF not just the AC compressor off.
 
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Old 04-21-2018, 09:57 PM
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Turns out I'm just a dumbass and was reading the tachomoter wrong. As far as the shaky idle is concerned I was told its not anything I should be concerned about. Thanks for the help
 
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Old 04-22-2018, 02:43 AM
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Yeah, gotta understand that the very first line on the taco-meter is 500rpm. The next 250 is actually 750.
 
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