Author Topic: IAC setup  (Read 47 times)

Offline DZGunner

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IAC setup
« on: November 17, 2020, 03:38:13 am »
I'm very new to much of this stuff so this is all a learning experience for me, just bare that in mind please. So I have an ISV that has a limp home mode in its full resting position. I used the IAC lock to determine that 31% PWM would hold it in its closed position past the safe mode. I enter that value as the MIN PWM, and left max at 100%. With the key in the on position, but not cranking or running. the ISV duty cycle shows the 31% i entered as the min. (good) and when cranking or idling, it will show either the input cranking PWM or what ever PWM for that given temp according to the reference table. (good) However when I actually drive the car, i see that the ISV duty cycle goes all the way to 0% when im just cruising. Shouldn't it only be going to 31%? sinse i set that as its min duty cycle? What would cause it to do this?
 
So again, I'm very new to this, but how steady exactly should an idle be with a properly set up ISV. Are we talking like rock solid 850 RPM + or - 5 RPM? or is it pretty normal for a car with this setup to fluctuate between lets say 830 RPM and 880 RPM?

I've been messing with the ISV with the IAC lock to see what sort of impact i can have on the engine, and it seems like after a certain amount of opening, it has no influence on the idle speed.

I know i should prob ask this next question in a different thread, but whats the proper sequence of adjustments to get the idle at cold starts to actually respond to input. I ask this because basically my cold starts (-4c - 10c) are very rough, and the car idles very very low, i force the ISV open and it seems to not help. I've also used the ign lock to raise the advance to like 25 degrees to help get the car just to start. I guess i just dont understand what exactly i should be changing first, so that i dont have to keep changing other things (like the VE table)

If you guys like i could upload a vems log of the car starting (cold) all the way to driving. If you think a shorter log might be better or two separate logs let me know. Thanks in advance.

Offline DZGunner

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Re: IAC setup
« Reply #1 on: November 18, 2020, 01:10:47 am »
So i adjusted the factory screw on the ISV to get rid of the safe mode all together, sinse VEMS doesn't seem to care what i set at the min PWM. The car runs a lot better.