'747 IAC idle reset

[rr]

Just in from r&r research:

After adjusting the throttle blade screw to open the blades more,
the ecm needs to be restarted in order to bring the idle down.

While the engine is running, and the screw is turned in, the ecm
will not adjust the IAC lower. The ignition needs to be turned
off for a minimum of four to five seconds (count from 1000-1
to 1000-ten), and the engine retarted. This will cause an idle reset.

On the other side, while the engine is running, if the screw is
turned out (lowering the idle), the ecm will adjust the IAC higher
to bring the idle back within spec.

I could not get the idle to reset after exceeding 45 mph. It was
only with an ecm restart. (did not need a battery disconnect).

So, with the engine off, crank the screw in a couple of turns,
and start the engine. Wait a minute for the choke terms to
decay out, and set the throttle blade screw to the desired IAC
counts. (of course do this with a warm engine).

BobR.


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