IAC Counts

[Walter Sherwin]

GM changed the fuel pressure spec for the 94-98 L19 TBI engine only, from
9-13psig to 26-32psig.  I'm pretty sure the other TBI engines did not
change, although the same concept applies.

Where would I find your "Tune-Up" notes?  I would love to read them.  Your
fuel pressure setup is variable .............. Have you altered the injector
constant, and the EGR mass tables to match?  Or did you leave as was?  Just
curious.

Bye.


-----Original Message-----
From: Bruce Plecan <nacelp at bright.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Sunday, October 11, 1998 4:23 PM
Subject: Re: IAC Counts


>
>-----Original Message-----
>From: Walter Sherwin <wsherwin at idirect.com>
>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>Date: Sunday, October 11, 1998 6:17 PM
>Subject: Re: IAC Counts
>
>
>>Your comments about the interaction of IAC counts, injector positioning,
>and
>>fuel spray pattern with a TBI were great!  I have also twiddled with these
>>parameters and have found the same results.  How many IAC counts do you
aim
>>for (warm 5-8 ?)?
>
>0,Zero. If when the rad fan kicks on, or some other draw 5-8.
>
>   I have also found that the Rochester TBI injectors
>>respond positively to more fuel pressure.
>
>Yep,  in the tune-up notes, I mention using two fuel pressure
>regulators.  One being vacuumed referenced to the engine, and
>the second one to clip it at a specific psi.  Also, does wonders
>for deccleration (clean+responsive).
>
>  The reward is slightly better
>>"shattering" of the fuel and a steeper, more regularly defined cone which
>>helps to reduce part throttle mixture maldistribution (especially with the
>>big 454 blades which tend to "paddle" the fuel towards the rear
cylinders).
>>Of course, the injector constant has to be changed to match the new flow
>>resulting from the increased pressure differential.  Starting in 94, GM
>also
>>moved in this direction, with a target system pressure of 26-32psig.
>
>That is news to me.  Or is this for the CFI system?.
>
>Cheers
>Bruce
>>
>>