Whit,
The hi performance PCM (computer) has a new fuel map associated with it, the
net result is that the injector pulse width is increased wherever the
software designer
figured he or she needed additional fuel. I really don't know where the
transducer is but if you hook up a scan tool, one of the options that you
can check is the
fuel pressure. I haven't been able to find it in the engine compartment, so
I would suspect it is somewhere near the fuel tank or incorporated in the
fuel pump
assembly. The Vortech supercharger kit includes an additional in-line fuel
pump and a FMU that changes the fuel system into a semi return system and
the FMU
just restricts the return line to boost fuel pressure. On my truck, we check
fuel/air ratio in the exhaust path before the Cat. (expensive equipment
required and
generally used in conjunction with a dyno). If you really feel that you are
not getting enough fuel (need to verify this on a dyno), you could explore
the avenue of
higher fuel pressure or step up to a larger injector even yet. Remember
though, in cruse and idle (operating temperature), the O2 sensor in
conjunction with the
computer is controlling your fuel/air ratio. Only at WOT do the fixed fuel
maps come into play.
> -----Original Message-----
> From: Whit [SMTP:bigdog@netdog.com]
> Sent: Wednesday, October 14, 1998 5:43 PM
> To: dakota-truck@buffnet.net
> Subject: Re: DML: RE: Fuel Pressure Regulators
>
> At 04:44 PM 10/14/98 -0700, you wrote:
> >Whit,
> >I don't know if anyone makes an adjustable fuel pressure regulator for
> the
> >Magnum, but I would think that it would almost be a moot point. The
> >regulator is built
> >into the fuel pump assembly, and additionally, there is a transducer that
> >sends signals to the engine controller on what the fuel pressure is and
> the
> >controller
> >adjusts the injector pulse width accordingly. If you wanted to increase
> the
> >pressure, you would need to run an in-line fuel pump downstream of the
> >transducer. If
> >you chose to go this route, you could run just about any aftermarket
> >regulator in conjunction with the in-line pump...
>
> I'll buy that. So tell me this, what does a hi performance PCM do with
> this function. I assume it takes those same pressure readings and
> correlates a longer pulse width thus pushing in more fuel?
>
> Here's the deal. I have additional volume (both stroke and bore) in my
> cylinders and I have larger injectors as well. The result is that I am
> not
> getting enough fuel into the cylinders (I have not checked this but will
> as
> soon as I figure out how to). It sounds as though I could use an inline
> pump to boost the pressure (hence the volume of fuel) and trick the
> computer by putting it after the transducer. BTW, where is the
> transducer?
> Probably not the ideal way to solve this but it seems cheaper than
> reprogramming the PCM whenever I make modifications. Thanks.
>
> Whit
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