Trouble with idle speed in park

**RobertISaar** · 04-11-2012

it almost sounds like the ECM is purposely commanding that high of an idle speed.

don't suppose $42 outputs the commanded idle speed in the datastream, or at least someone knows the RAM location of it?

**EagleMark** · 04-11-2012

51 IAC counts is a little high but should work. It also indicates IAC is controlling idle and not a vacuum leak controlling idle. But a vacuum leak realy messes up MAP reading and adds fuel and messes up O2 reading and well vacuum leaks are not good.

Change all IAC paremeters back to stock for now.

When you do the IAC reset and IAC is all the way closed you pull IAC plug and set idle to 100 below commanded Closed Loop Idle if your bin is a closed loop idle bin and motor is well warmed up and in CL. Look for the Idle speed here "IAC - Desired C/L Idle Speed"

Do you have a Park/Neutral switch? Do you have a VSS? Did you clear codes after the reset and after setting timing? Do you have any codes after having no codes and driving around a bit? Is motor stock? If not what is vacuum at idle? Steady reading?

**srobertsfsj** · 04-11-2012

Do you have a Park/Neutral switch? Yes
Do you have a VSS? Yes
Did you clear codes after the reset and after setting timing? Yes
Do you have any codes after having no codes and driving around a bit? No
Is motor stock? Stock AMC360
If not what is vacuum at idle? 17
Steady reading? yes

I reset the IAC again, and i noticed that the IAC makes kind of a grinding noise when its reseting, is this normal? Also, I noticed that now my IAC is at 72 at idle.

**EagleMark** · 04-11-2012

Yes the IAC will make noise when it is forced in by crossing A and B on ALDL.

Find the idle in bin for warmed up temp or change to what you want. Leave a little high when cold, let it get higher when hot, but keep the area around idle the same. Now you have say 700 RPM set there. Warm up motor totally and even take for a ride. At idle are you closed loop? Yes, turn off motor, cross A and B turn key on, no start, and IAC will set closed before you can get to it and unplug connector, go back turn key off. Start vehicle and set idle to 600 after it has gone closed loop again, even rev motor up a little and let idle settle in closed loop, there is usually a timer when first started. Turn motor off, plug in IAC, clear codes restart and tell us what happens now. What RPM does idle go to when it enters closed loop? What are IAC counts?