P4 ECM #1227748 questions

[Nick McAlpin]

first, thanks to everyone who replied to my question, i appreciate it! 
 it's amazing the stuff i've learned in the past day or three.

second, specific question - is there an .ECU file available for ECM 
1227748?  I coudln't find one on the FTP site.

third, I subscribed to the alldata web site to view the TSB's for the 
car, and there have been four issues fixed via 5 different PROM's 
including a high idle RPM issue.  I was able to order the 
appropriate updated PROM, and hopefully it fixes it.  will let the list 
know in a few days when I get it.

if not, and if I can get an ECU for the 1227748, then i'll probably 
invest in the hardware to reduce the # of steps the IAC is stepped 
out (oh, say, cut it in half!!!).  I used EEPROM's in college only a 
few years ago, I should be able to burn EPROMS now...(how's that 
for overconfident!)

Finally, I will try the trick of lowering the minimum idle rpm back to 
where it was and even then some.

thanks again, everyone.

nick

> The ECMs of that generation don't command a specific fast idle speed.
> Instead, they simply open the IAC x counts beyond the learned idle
> position.  Not x% more air flow, not x% pintle movement, not x% more
> steps, but simply x steps.  This means that the amount of additional air
> depends on the normal idle IAC position.  Going from position 10 to 40
> is probably a much bigger change than going from 110 to 140.
> 
> Try adjusting your minimum idle speed down.  This should force the ECM
> to open the IAC more during normal idle.  Hopefully that'll result in a
> lower fast idle.
> 
> BTW, the ECM will keep the idle slightly high while the VSS registers
> movement.  Only when the car stops moving does the idle go down to the
> target rpm.

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