IAC vs Coolant actual settings

[Darrell Tuxworth]

OK. Here's the deal.
13 deg C and IAC is at 120 counts when engine starts and runs. It does drop a few counts....like 3 after 1 minute of running.
Voltage 14.3

PROM setting
6 deg C counts 90
16 deg C counts 85
Park setting 100 counts.

So why does the ECM not do what the PROM is telling it to do? This scenario plays all the way through until the engine reaches FULL operating temp... the engine rarely idles down to the programmed 650 rpm setting which starts at 55 deg C?

The IAC sometimes hold the RPM at 2-300 more rpm at an idle than what the PROM is set at even after driving for hours.
I have changed IAC motors to no avail.

Darrell

[Bill usn-1]

I looked at your last bin you sent and the log.
The IAC park was 145 but you didn't log from initial start up and you didn't log flag data, only error codes.

I have had many bins that don't specifically follow the IAC table.
You would have to get into the hack to see what takes priority in tables.
Is it AFR at idle, rpm, timing, IAC/temp...etc.
I used to try the 454 bins as a base line but they didn't have any fast idle in the morning. Rather then take the time to figure it all out I simply went back to the 5.7 bin and adjusted the AE.

Back in the day...years ago, I would set the park to 100 which seemed to help the warm start time. It closes off some of the big vaccum leak and I think it kept the intake from drying out went the motor was turned off.
So it took less motor turns to start.

[Darrell Tuxworth]

Bill.
The last file I sent you has likely been greatly played with so you can't use it for reference any longer.
I figured it was something buried deep in the chip that I didn't have access to. I don't have the info to know how to interpret the hack. Are you using the ASDU file for your base these days? I can't remember what I was using as my base but if you have one that has been working well I would like to try it.
Yes I would change all of the tables and such but am more interested in what I can't adjust in the chip.
Thanks
Darrell

[Bill usn-1]

I've tried others thinking the older bins may work better on our older designed engines. I just tried the ADYR which was for a 5.7 man but it really had some bad issues. So I think I will stick with the ASDU or a bin I personally read from a chip and not one downloaded.
Send me your engine/system specs.

[EagleMark]

What engine? Stock? What thermastat? What ECM and chip? Where is coolant tempreture sensor located?

[Darrell Tuxworth]

What engine? Stock? 345 9.0 :1, bored .030. Isky 252/256 cam dual exhaust stock exhaust manifolds
What thermastat? RS 180
What ECM and chip? 7747 custom chip...as stated I don't remember what the base was
Where is coolant tempreture sensor located? In the intake in a port on the drivers side next to the throttle bracket.

[Darrell Tuxworth]

I moved all my engines pertinents over to a ASDU bin. All I have done thus far is a start up and run up to operating temp. No change in the IAC counts...at least it still isn't hitting the "IAC vs Coolant temp" tables number yet it might be different from what the old chip (before the ASDU I just put in) was in there ...All I can tell yet is the engine seemed to start a little quicker...maybe.
Gonna be a while before I get it out and drive it tho.
Darrell

[EagleMark]

What is your coolant temperature in WinALDL or scantool?

Reason I ask is I have never had this problem and there are plenty of IH engines out there that have been converted to EFI. But most if not all use the plugged hole in thermastat housing. This plugged hole is the perfect spot for a CTS as it measures tempreture in coolant bypass.

[Darrell Tuxworth]

Mark.
The temps I was giving are the temps the ECM is reading. I have the mechanical temp gauge sensor in the thermostat housing...Since this is the one I use for everyday driving and once the engine is up to temp the two areas are within a few degrees of each other I would guess.....I have watched both and they seem to stay relative.
So your saying that the IAC counts match what is programmed into the IAC vs Coolant temp tables exactly? Have you verified this?
Darrell

[EagleMark]

Have I verified this? No... I am trying to on the bench. Now that you have a known chip (ASDU) I may be able to.

From experience I know that issues like this have been tied to CTS location on many vehicles. An IH known perfect location is the thermostat housing plug. If you look at a SBC the CTS is in same area (function).

I will read the information you had given and convert to Fahrenheit to see what warmed up temp you are reading... if you have a WinALDL data log you can look down the column and see what it is doing while warming up to operating temps.