[Gmecm] creepy idle

[Steve Ravet]

________________________________

	From: gmecm-bounces at diy-efi.org
[mailto:gmecm-bounces at diy-efi.org] On Behalf Of Andrew Gibson
	Sent: Thursday, January 26, 2006 2:54 PM
	To: gmecm at diy-efi.org
	Subject: [Gmecm] creepy idle
	
	
	Steve it sounds like a load issue. Since it idles like it should
in neutral but not drive, even with the bad prndl switch, you need to be
looking at the precived engine load aka MAP, a/c input, etc. Anything
that would make the ecm want to go higher on the idle. This alone
shouldn't be an issue though. 
	 

Thanks for the reply, since I posted I have checked the MAP.  It reads
100kpa key on engine off so should be fine.  It reads 45 kpa idling in
neutral, and around 65 kpa idling in gear, before the IAC starts opening
up.  PN switch is the only thing left at this point, I'll get it working
and report back.  A/C request is reported correctly on the scan tool.

	 
	With an auto trans the IAC shouldn't be over 50 at 750 rpm.
Check the stall speed on your torque converter. It may have balloned and
reduced the stall speed thereby making it impossible to attain 737 rpm
in drive or any gear for that matter.
	 

I can rev it higher with the throttle, it's just the IAC can't seem to
flow enough air to get it over 725 when the computer wants 737.  I treat
this truck very gently (289K miles total, 159K on the engine) so there
better not be any ballooned TCs!
 
thanks for the suggestions, I'll write back when I know more.  For now I
shift into neutral at stop lights.
 
--steve
 
 

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