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Thread: What is the ideal iac percentage?

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2015-07-12 03:46:42
What is the ideal iac percentage?
I am looking at my iac percentage and it shows 95% during idle and on throttle. My car is having trouble to stay idle when I let off the throttle and sudden complete stop . People think I want to race at the stop light just because I have to rev just to keep the engine running.. I read somewhere that iacv percentage should be around 50%.

2015-07-12 12:14:29
Ideal is maybe a bad description but it should be lower, IIRC mines is around 28%, it depends on how well adjusted the throttle plate is, how much wear is in the throttle body. The adjustment of the Idle Screw. Have you done a base idle/timing setting? Anyway 95% is very wrong. I suspect IACV needs cleaning or is failed/failing. A clog in the IACV feed line, A kink maybe. Most issues can be identified and solved by a simple look-see.
2015-07-12 12:54:19
I think 50% is going to be a way better place than 95% for sure. But as yoshoto said, maybe even lower is ideal.
It's possible your idle screw has been screwed too far in at one point, but adjusting that is always a last resort.
Check everything else first.
2015-07-12 13:33:15
For the B13, it should be 20% with engine fully warmed up and idle at 750rpm. This gives the ECU some "head room" to maintain idle speed when loads (A/C, electrical) are applied and to increase idle speed during warmup.
2015-07-12 23:44:14
I already disassemble and clean the iacv. Should I Turn the screws to lower the idle rpm. My idle is 1000 rpm fully warm, that's what the nismotronicSA do in the calibration set up... Do I need to lower the base target idle rpm. What else do I need to check? I am going to do base idle timing first , I really don't know what it will do.
2015-07-13 01:21:46
I turn the screw counterclockwise all the way up and got 10% duty. Run much better now, not dying as much but still die sometimes.. Thanks everyone and nismotronic.
2015-07-13 13:12:56
Have you tested the IACV coil with an ohmmeter?

Also with the IACV unbolted from the mani you can see the plunger move when the ignition is turned on.

The screw shouldn't be all the way out but set to give "base idle" rpm at correct mechanical base idle timing.

Is the AAC valve functioning as well? When u turn on AC or turn the steering(assuming u have PS)?
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