5.7L TBI stalling and low idle help

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DiGiTaL D

Newbie
Joined
Dec 21, 2015
Messages
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Location
Greenwood, IN
Connect a scan tool, look at commanded idle speed vs. actual idle speed. Perhaps the IAC or the IAC wire harness is defective.

How old is the O2 sensor?
I am back with some data.

When the engine is cold, the O₂ cross count starts low and runs up to approximately 250. It then rolls back over to a low value, say 14 or 16, and runs back up to around 250 again.

Commanded idle speed does not appear in the available live data.

With A/C not requested (off) idle speed hangs around 650 RPM. With A/C requested (on) idle speed hangs around 700 RPM but I did see it go as high as 725 RPM.

When A/C is requested, idle air motor position is approximately 47.

When A/C is not requested, idle air motor position is approximately 24.

I did notice that once the engine warms up, the O₂ cross count slows way, way down.

When it is in the process of stalling out (A/C on, in gear, stationary turning steering wheel thus loading the power steering pump and drive belt system) the idle air motor position advanced rapidly from 40 to 91 at the approximate point of stall, then topped out at 140 after the engine actually stopped.
 
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