What would cause "desired idle" to be 1200 RPM's??

M

MNSy2899

New member
Intermittent high idle. When I put it in neutral when rolling up to a stoplight, the RPM's go up to about 1500, then settle back down to about 900. As soon as I put it back in drive the engine loads up on the tranny and wants to move w/o giving it any gas. On Diacom when this happens it shows the desired idle to be 1200 RPM's. Where do I look for the cause of this problem? Vac leak? Electrical? Bad ECM? IAC?

Thanks for any help,

Adam
Sy 2899
 
S

sy2185

New member
also check your drive/ neutral sensor (can't remember where-shifter or trans, pretty sure it's in the shifter/center console area) it varies the idle if the ecm thinks it's in gear or not. Mine was misaligned and it gave me a low idle in drive and 1200-1500 in neutral/park. Have also seen low N idle and let off the brakes in D w/ no throttle and you'll soon be doing 10-15mph. Just a thought.
Jeremy
 
T

typhoonzz

Got Boost?
smeagol said:
FWIW, if you see desired idle of 1250 on Diacom, it is in ALDL MODE
Click to expand...
Mr Green is correct
I did the same thing and felt like an ass till I figured it out :)
Before you link, go to mode and set as normal, not aldl. Idle will be correct then...
 
Ian Turgeon

Ian Turgeon

Cascading Inspiration
ALDL mode, no good.. did that myself.. conciderably harder to stop the truck when its trying to idle at 1200 rpm.

freaked me out at first.
 
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