High searching Idle

[jss06c6]

Oh, and I don't have any issues with stalling. Used to, but tuned that out. No trouble any more.

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[jss06c6]

Originally Posted by mike100

These throttle bodies and the pcv vent bypass too much air an it is hard to get a positive IAC number. I was able to get a value of 10-20 on the iac counts after I restricted the diameter of the pcv hose to the manifold. To make up for the pcv flow at high rpm where it needs the full tube, I tee'd off to a mini filter atmospheric vent.

Mike,

What do we gain trying to hit IAC of 10? If the car idles butter smooth and doesn't stall coming to a stop, what is the "win" with IAC sitting at 10? Just don't understand why we should chase this and suffer top end starvation like you describe.

Steve

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[XfireZ51]

Originally Posted by jss06c6

Hans,

Yes, ideally this is the case. I run my idle at 700 rpm. If I move up to 850, IAC will be at 10-15. When I set minimum with the IAC pintle fully closed, I set it to 600 RPM. Then reset the TPS to 0.55 volts. Plugged the IAC back in and it settled in and slowly walked back to 0. Can't get the idle any lower with the IAC disengaged. If I moved my idle speed up, no problem holding 10.

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How are you setting the Min Air? Let’s review to make sure its correct.
The objective of Min Air is to require a small amount of IAC enough so that it has margin to intervene and prevent a stall but not so much as to override what should be mechanically done by TB opening.
IOW, u set the idle speed somewhat below the desired idle so that the IAC actually controls idle speed, but with few counts, ie 10-15.
BTW, I have situations where my IAC drops over time. There are modifiers in the cal that pull IAC counts based on MAT. I try to set Min Air with the motor hot and with fans ON.

[jss06c6]

Dominic,

I set the minimum air by locking the pintle in the full open position (ignition run with IAC unplugged). Starting the car.. setting TB to 625-650 rpm. Reset TPS to 0.55 volts. Shutting it down. Pulling negative battery cable. Wait 5 minutes. Reconnect IAC harness. Reconnect battery. Start engine. Observed IAC at 140 upon start. Slowly worked it's way down and within 2-3 minutes it was back at 0. Engine idling at 725-750, as commanded. Hot engine during setup.

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[XfireZ51]

Originally Posted by jss06c6

Dominic,

I set the minimum air by locking the pintle in the full open position (ignition run with IAC unplugged). Starting the car.. setting TB to 625-650 rpm. Reset TPS to 0.55 volts. Shutting it down. Pulling negative battery cable. Wait 5 minutes. Reconnect IAC harness. Reconnect battery. Start engine. Observed IAC at 140 upon start. Slowly worked it's way down and within 2-3 minutes it was back at 0. Engine idling at 725-750, as commanded. Hot engine during setup.

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Just to be clear, you put the ECM in ALDL/Diag mode, turn ignition to ON before
disconnecting IAC motor, turn ignition OFF, then disconnect ALDL, then re-START the motor. I let it idle until fans kick in, then adjust TB.
Have u modified the IAC tables at all?
The stock calibration has an idle of about 650. I’d be interested in hearing what someone w a stock motor has for IAC counts at idle. I know the commanded counts are not 0.

[jss06c6]

Yes regarding ALDL set to diagnostic mode.

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[jss06c6]

Need to look at IAC tables. I haven't changed them. Not sure if Marc's tune changed them, but doubt it.

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[XfireZ51]

Originally Posted by jss06c6

Need to look at IAC tables. I haven't changed them. Not sure if Marc's tune changed them, but doubt it.

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I don’t think he plays w them. I just refreshed my memory re: stock cal, and it commands an IAC count of 30 at 0 mph with an idle of 650rpm.

[jss06c6]

Let me look at mine..

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[jss06c6]

Only two tables in my XDF..