[Gmecm] Re: TBI 350

[Jared Ryan]

The more I think about it, the more I wonder if this engine would really benefit from the vacuum-controlled regulator.  The issue seems to be that if I raise the pressure enough that it doesn't ping on acceleration, it doesn't idle very well at all.  The vacuum-controlled regulator would seem to address that very issue.

Here is what I don't understand: is there some minimum duty cycle of the injectors?  If I raise the fuel pressure, I increase the amount of fuel that comes out of each injector in each pulse.  Why, then, does the ECM just not pulse the injectors less often, to lean out the mixture at idle?  It's this part of the programming that I don't understand.  I thought, when I put the adjustable regulator on, that the ECM would just compensate and everything would be right.

I do need to say that even though the idle is horrible right now, it starts *very* fast, especially when cold.  With the old stock non-adjustable regulator, it took a few seconds of cranking to get it to start, especially when cold.  With the JET adjustable regulator at its minimum pressure, it starts very quickly, as fast as a carburetor-equipped engine with choke set exactly right.

I have ordered a fuel pressure gauge with Schraeder-valve adapter and paid for next-day-air shipping, so hopefully by Saturday I will be able to report exactly what the fuel pressure is at idle and at wide-open throttle.

I will look at the Lindertech material you mentioned and try to learn more while I wait for the pressure gauge.

 - Jared Ryan [jryan at caminofx.org]

On Wed, 12 Jul 2006 20:02:22 -0700 (PDT), Andrew Gibson <andrewsharyn at yahoo.com> wrote:
> Jared personally I am a great fan of the vacuum controlled regulator. Just
> because it provides enleanment on decel and enrichment on accel much
> better controlled than your fuel tables can. Newer cars with bigger tables
> can easily run returnless or fixed pressure.
> 
>   Here's my reccomendation. Pull off your fuel pressure regulator, put a
> new diaphram in it (they're cheap) extract the pressure control bolt out
> and put one in you can adjust. Then bump your pressure up a little and it
> will increase all the way across the board without totally screwing up all
> the research you have done for your current chip.
> 
>   If you go to lindertech dot com in the archives they have a 1bbl tbi
> build that they did this to. Your tbi will be similar, but with 2 barrels
> :)
> 
>   Keep tinkering it's better than sitting around drinking booze with
> friends bragging about how much horsepower your brother's roomate's
> nephew's Honda makes!
> 
> 
> ---------------------------------
> Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls.  Great
> rates starting at 1?/min.
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/gmecm
> Main WWW page: http://www.diy-efi.org/gmecm
-- 
 - Jared Ryan [jryan at caminofx.org]