LS motor high idle

GubNi

GubNi

8 lug disc brakes?
Joined
Mar 20, 2005
Location
Jonesborough, TN
My buggy has an LS 6.0 motor. It has been running good for a few years. I swapped in a new transmission and now idle is 1500 and goes to 2000 sometimes. I don't think there is any chance the trans is the problem. I suspect I knocked something loose during the process or maybe something went bad while it has been sitting during the last year or so. I have checked a few things and I have not seen the problem. I tried to scan but it says unable to communicate with ECU. I suspect the scan problem is related to the tune somehow.

Any ideas on what I can check? I'm in Harlan for the weekend.
 
It's probably the idle air control motor. It's on the throttle body and they usually get gummed up with carbon/oil/dirt and start to stick. Pull it off, clean out the bore it sits in, clean the IAC itself, push the plunger in and pull it out, and slap it back together. Should keep it going for a while. Mine did that a few years ago and I just cleaned it.
 
Could def be IAC as mentioned. Also, if this just started immediately after trans swap, check to see if you busted or cracked off any of the vacuum nipples on the back of the intake manifold. Check for pinched wires as well in the bellhousing area, that can cause all sorts of weird stuff. If MAF, MAP or TPS are unplugged you can have a high idle.
 
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