bad iacv cause hard start
06-25-2012, 06:25 PM
#1
bad iacv cause hard start
Ive done everything a maxima owner could do fuses relays ignition switch stater plugs few coils fuel pump filter knock sensor cam sen both crank sensors maf grounds ...onlything seem to work is if i adjust itall the way out and play with it working it in to start..sometimes it will be fine some days back to adjusting it..ive took it apart cleaned it out put it back together does same thing...its runs great when running no idling problems but its unplugged and sti runs fine with it unplugged but i has to be adjusted in order for it to even hit if i dont it will flood back fire...so idk
06-26-2012, 05:29 AM
#5
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The car will run with the IACV disconnected. Technically the only thing you should see is a low idle speed. The process of setting the default idle speed involves disconnection the TPS which disables the IACV. That's how you set the throttle body default idle which is vital for proper operation of the idle control valve.
A hard start shouldn't be caused by a defective IACV. The throttle body cold idle circuit opens the throttle plate to allow for the additional air needed for a cold start. A warm engine should also easily start with a defective IACV, only issue would be an improper idle speed and lack of idle speed control when an addition load is put on the engine.
A hard start shouldn't be caused by a defective IACV. The throttle body cold idle circuit opens the throttle plate to allow for the additional air needed for a cold start. A warm engine should also easily start with a defective IACV, only issue would be an improper idle speed and lack of idle speed control when an addition load is put on the engine.
06-26-2012, 08:37 AM
#6
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Join Date: Sep 2009
Location: Worcester, MA
Posts: 4,011
Ive done everything a maxima owner could do fuses relays ignition switch stater plugs few coils fuel pump filter knock sensor cam sen both crank sensors maf grounds ...onlything seem to work is if i adjust itall the way out and play with it working it in to start..sometimes it will be fine some days back to adjusting it..ive took it apart cleaned it out put it back together does same thing...its runs great when running no idling problems but its unplugged and sti runs fine with it unplugged but i has to be adjusted in order for it to even hit if i dont it will flood back fire...so idk
THe Idle air control valve is a step motor that opens per the inputs from the TPS, VSS, and ECU. while idling it allows a small amount of air to bypass the throttle body plate thus allowing u to idle at a much lower rpm than cracking opening the throttle plate.
If the throttle plate is adjusted to be mostly open, then there is no need to bypass air via the IACV. Only problem is, u are burning more gas since now your idle is higher than normal.
The TPS could be messed up too. The test for the TPS is a voltage test.
Last edited by cashoit; 06-26-2012 at 08:44 AM.
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