EFI idle question.
Elite HDF Member
Joined: Nov 2005
Posts: 3,654
Likes: 362
From: Mansfield Texas
That is a base idle screw, your idle is controlled by the Idle Air Control Motor on top of the throttle body. That screw is to create a base idle speed that the idle drops to before the IAC takes over, screwing in will raise the idle and cause the IAC to want to close more till the PCM sees the correct idle speed, and screwing it out will lower the idle causing the IAC to open more to compensate. This can cause a unstable idle or stalling problem. There is a correct procedure for adjusting it.
Elite HDF Member
Joined: Nov 2005
Posts: 3,654
Likes: 362
From: Mansfield Texas
Yes a low idle will starve the top end of oil, the oil light pressure won't always come on at a low idle because it is measuring pressure at the bottom end.
Road Master
Joined: Oct 2010
Posts: 958
Likes: 0
From: Hartford, WI
Your Idle Air Control is a "controlled air leak" that will change the base idle. If you try to open it up more, it won't work. The ECM will command an idle speed and the IAC will open or close to achieve it. If you push it out of adjustment, what will happen is that the ECM can no longer compensate and you can have unstable idle.
Why do you want it higher? I'd see a dealership before you screw it up.
Why do you want it higher? I'd see a dealership before you screw it up.
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Road Master
Joined: Sep 2011
Posts: 764
Likes: 1
From: N. Texas
I don't want it higher. I want it lower. Since I've added a free flow AC & free flowing exhaust, it seems the motor is breathing too easy & making the idle too high. It has zero lope to it. It's more of a constant purr, even @ idle. If Barry would meet me Sunday I could figure out if it's high or not!!!
Road Master
Joined: Oct 2010
Posts: 958
Likes: 0
From: Hartford, WI
I don't want it higher. I want it lower. Since I've added a free flow AC & free flowing exhaust, it seems the motor is breathing too easy & making the idle too high. It has zero lope to it. It's more of a constant purr, even @ idle. If Barry would meet me Sunday I could figure out if it's high or not!!!
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Road Master
Joined: Sep 2011
Posts: 764
Likes: 1
From: N. Texas
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Road Master
Joined: Oct 2010
Posts: 958
Likes: 0
From: Hartford, WI
I guess you either live with it or dump this and get a tuner like SEPST or PowerVision that CAN do everything. I am going with SEPST because the wife bought it for me or I might have gone eith PowerVision for that total adjustment ability.
Elite HDF Member
Joined: Nov 2005
Posts: 3,654
Likes: 362
From: Mansfield Texas
Maybe its not changing the idle speed but while adjusting the fuel mixture...makes it idle smoother????? just a thought.