[Gmecm] Idle problem

[charles at taildragger.info]

Are you guys using a tach to see the RPM, or the ALDL data?  Maybe the
ALDL data actually says 750?  I'm far from an expert, but there are things
that could mess up the perceived RPM by the computer, like # cylinders.

> On Monday 22 August 2005 12:03, Programmer wrote:
>> Those IAC numbers are not indicating a vacuum leak.
>> Check the "P/N" signal to the computer. If it's getting an 'ingear'
>> signal
>> when you're actually in park, you'll have a high idle. Another problem
>> is a
>> false VSS signal (from RFI or EMI) down the signal line to the computer
>> (if
>> it thinks you're on the move, the IAC counts will rise). Drop your
>> commanded RPM values...750 doesn't really equal 750...
>
> How is it that 750!=750? ... I have this problem too: I just did a swap
> from a
> carb to a 7747 ECM + TBI on a Ford 302, and the set the idles to about
> 850RPM
> (a bit bigger than stock cam), and I get about 1200 RPM no matter what I
> do
> too. The IAC speeds the thing up whenever I do something to lower it.
>
> I'm sure the P/N switch signal is in "N", and the ALDL data doesen't show
> any
> VSS pulses.
>
> The closed loop also kicks in at a temp much-much higher (about 85?C) than
> what the calibration says (35?C). Why these discrepancies?
>
> --
> Tomas J. Sokorai Sch.
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