IAC Counts

Walter Sherwin wsherwin at idirect.com
Mon Oct 12 16:15:01 GMT 1998


Thanks.


-----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 10:27 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: Monday, October 12, 1998 12:10 AM
>Subject: Re: IAC Counts
>
>
>>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.
>
>At the bottom of the DIY_EFI page is a referral to 332 go over there,
>and at incoming click on that, and you'll be at the ftp site.  Look
>for a couple files about tune-up doc/txt.  My PC is acting up, so I
>can't get to my notes here.  If ya have troubles maybe some one
>would post the exact address.
>
>Your
>>fuel pressure setup is variable .............. Have you altered the
>injector
>>constant, and the EGR mass tables to match?
>
>I just recently found some related info to that end, and haven't played
>with it yet.
>
>  Or did you leave as was?  Just
>>curious.
>
>So far as is.
>Bruce
>
>>
>>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
>>>>
>>>>
>>
>>




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