Closing in on a problem

[EagleMark]

If the IAC count is 12 when vehicle is totally warmed up after a highway drive while stopped in drive? Perfect! Litte higher IAC count when neutral...

If idle is higher/lower RPM then desired? Change it in chip.

[lionelhutz]

But in neutral with no engine load wouldn't the rpm rise unless the IAC motor closed more, not opened more???

At any rate, I would try closing the throttle blades more and see what happens.

[EagleMark]

But in neutral with no engine load wouldn't the rpm rise unless the IAC motor closed more, not opened more??? .

Your right, lower IAC... never let go to 0 IAC counts though.

[1great40]

Lionel, I'm not having a problem with a high idle speed, the idle is too low. Right now the IAC numbers are around 12 in park and a little higher in drive. From what I have observed, I want to have the largest quantity of the idle air coming by the throttle plate and a minimum admitted through the IAC without the IAC ever going to zero. When the throttle on a TBI engine is closed too much, it will still idle by virtue of the IAC admitting air but that air then has to mix with a dribble if fuel dripping past a closed throttle plate, not the best scenario for getting good vaporization. The more fuel spray that gets by the throttle plates, the better it mixes with the air.
So, the minimum air setting seems to be just fine, the ECM commands a high idle when the engine starts, the engine also goes to the correct speed when in 10K mode. As of now I'm pretty confident that the IAC is working, the ECM is working and the last piece of the puzzle is to use TunerPro to see what the actual values for idle speed are in the PROM. The stock PROM seems to make the engine idle at 600 RPM. The Prom that I'm using now that EagleMark made for me is supposed to have the idle set to 725 but with this PROM, the engine idles at about 550. First chance I get, I'm going to fire up the truck and look at the values. I understand there are many idle speed values for different conditions so, I'm at the beginning of another learning curve. Hopefully, this will be as simple as getting the PROM re-programmed but if the values are correct and the speed is still not right, I don't know where to look next!

[EagleMark]

Idle RPM is not accurate on this ECM, so at this point it needs to read higher. I need to send another chip with an additional 100 RPM. But until I get home I don't know of anoter way.

[1great40]

EagleMark, do you need me to mail the other chip to you?

[EagleMark]

Problem is I have been in hospital and rehabilitation since I did your chip and have no way to burn and mail another. But have someone who will, just need to contact him.