[Gmecm] Idle Speed

[Steve Ravet]

> -----Original Message-----
> From: gmecm-bounces at diy-efi.org 
> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of jryan at caminofx.org
> Sent: Tuesday, December 12, 2006 8:02 AM
> To: gmecm at diy-efi.org
> Subject: [Gmecm] Idle Speed
> 
> I have a new GM long-block 350 with a throttle body from a 
> Camaro and an Edelbrock 3704 intake manifold.  The ECM is a 
> 1228746, and I am using an ANLU PROM from an '89 9C1 Caprice.
> 
> All in all, the combination runs well, but I am curious about 
> something.
> 
> I went through the minimum idle speed procedure when the 
> weather was relatively cold (in the 40s F daytime).  I got it 
> to idle slow but smooth, around the speed set in the ECM 
> constants table in the PROM, about 560 RPM or so.
> 
> Lately, the weather has warmed up some (to the mid-70s F 
> daytime), and the engine seems to idle faster.  It was idling 
> at around 800 RPM when I shut off the engine after getting 
> home from work yesterday, and when I parked at work this morning.
> 
> Watching the temperature gauge in the dashboard, it seems 
> like, to a point, it idles faster as the engine temperature 
> increases.  I don't see any values in the PROM that would do 
> this, but I may have overlooked something.  Is this normal, 
> or should I look for something wrong?
> 
> For what it's worth, the Camaro throttle body does not have 
> an adjustable TPS.  It just screws on.  You can't move it.
> 
> On Saturday, I hooked up my laptop with WinALDL while it was 
> idling relatively fast, and it showed about 20 IAC counts, so 
> it would appear there isn't an uncontrolled vacuum leak.
> 
> Is this a sign of something wrong, something I can tune out 
> with a laptop or a scantool, or just the way it's programmed?
> 

You should be able to see the "commanded" or "desired" idle, which is
where the ECM is trying to keep the idle.  It changes IAC to get to
there.  What is commanded at the different idles?

There is a lot to idle.  On the gmecm page, look for the "papers by list
members" section and read the idle paper, also possibly the PID paper.

--steve