Hi Guys,

I'm still learning the art of PROM programming. I did a data log (attached CSV but renamed to TXT for upload) and noticed some knock retard I need to deal with. But what also caught my attention is the IAC counts seem to be 0 until about 1200rpm. I did some searches and it seems like there are a lot of opinions on what the idle counts should be.

Can anyone clarify what the IAC counts should be?

The datalog is in closed loop from a stop to about 55mph.

If anyone notices anything else I need to research, please let me know

Thanks!

 

Mine are a zero counts as well. Idle speed is commanded in .bin at say 700 rpms. IAC moves to maintain that speed. If you are at 725rpms it cannot reduce speed as it is already zero steps. Might be better at say 10 steps to allow that. Either the TSS is backed out or a vacuum leak...

 

Yup! Your idle is 713 RPM and above. What is it programmed to be in the bin file?

If it is below that (713) you will not see and IAC counts. If it is above 713 RPM then you would have an issue like vacuum leak.

I like a little IAC counts as the ECM is working to control idle. Like 10 to 30 at idle. How to set this is a minumum air setting on the throttle blades.

 

Thanks for the replies guys! I will look at what the idle is set at in the chip tonight and let you know. I do know that, in order to get my car to idle ok with my cam, I had to open the throttle stop to about 900rpm. It idles better this way but I still have about a 250rpm surge.

So if the chip isn't set to idle at 900rpm, will doing that make it idle better?

 

I found a recent data log and the desired idle is 750rpm.

 

Well if desired idle is set to 750 in the .bin then any time you are below 750 RPM you should get some IAC counts trying to raise it to 750 RPM.

Other things have to be met to get the desired idle to work. Not positive about your ECM but like full warm up tempreture is one, may be others... HTH!

 

CAM? Well that needs to be addressed.
Condsider idleing OL. Flatten all cells around your idle cell, make the same. If your mask allows lock SA Idle.

 

What's weird is, in my log above, the RPM is less than 750 (idling in drive) but the IAC counts are still 0?

 

Ronny, what is the advantage of adjusting the idle in Open Loop instead of Closed Loop?

Thanks!

 

OK you are commanded 750 in D. And you idle 713 per Eagle right. Steps are 0. You are right does not add up. Maybe tach is off? Maybe IAC is dirty?

Idle OL allows a richer commanded A/F AND no involvement of CL NBo2 sensor feedback, especially with cam reversion if a larger than stock cam.