Jason,
Aftermarket ignitions used on our trucks generally trigger off of the
voltage supplied to the coil. So the ignition just follows the instructions
of the computer. The Crane unit I use, timing sags approx. 1/2 degree over
the RPM range. The only way to compensate for this is by changing the
ignition Map in the computer.......
Frank
> -----Original Message-----
> From: Jason&Sarah [SMTP:Jpm699@email.msn.com]
> Sent: Friday, May 21, 1999 8:34 AM
> To: dakota-truck@buffnet.net
> Subject: DML: Re: RE: Re: MP PCM - How do they do it?
>
> For those of us running an MSD setup can the PCM really make a difference
> to
> the Ignition curve if the MSD is doing all the work? With modified
> engines
> can the PCM really do much good?
>
> Jason
>
>
>
>
> Mark,
>
> The ignition curve is changed and re-shaped, advance starts sooner.
> But the fuel map is untouched. This is true for all computers from 96
> through current.
>
> > -----Original Message-----
> > From: Mark Kuzia [SMTP:flyboy01@worldnet.att.net]
> > Sent: Thursday, May 20, 1999 7:28 PM
> > To: dakota-truck@buffnet.net
> > Subject: DML: Re: MP PCM - How do they do it?
> >
> > Jon,
> >
> > From what I understand by talking to programmers, they actually change
> the
> > shape of the curve and fuel flow. The stock computer limits timing
> advance
> > under 3000 rpm, over that they throw the timing back in, but only for
> the
> > next 2000, then they pull a little out again at 5000. The fuel curve is
> > overly rich which limits heat and detonation problem as well as reducing
> > horsepower. These problems seem to be worse in the 97+ engines.
> >
> > Aftermarket computer lean the fuel curve for more power and give plenty
> of
> > advance under 2400 rpms. They also give the sensors a wider set of
> > parameters for operation with higher lift cams. the 15 to 30 horsepower
> > gains depend on the level of modification, the more modified, the less
> > power
> > gained. !5 to 20 hp seems more accurate for modified trucks.
> >
> > Mark
> >
> >
> > -----Original Message-----
> > From: Jon Steiger <stei0302@cs.fredonia.edu>
> > To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
> > Date: Thursday, May 20, 1999 6:08 PM
> > Subject: DML: MP PCM - How do they do it?
> >
> >
> >
> > I believe this has been discussed to some extent in past (I have even
> > answered variations of this question), but I'm wondering if anyone out
> > there knows exactly what MP does to put the "performance" in their
> > "performance computers"?
> >
> > Here's the stuff I do know:
> >
> > The WOT fuel maps are richer.
> > The timing is advanced. (I think I have heard 4 degrees?)
> >
> > Of course, the rev limiter and speed governer are altered as well,
> but
> > they don't have any direct effect on the power output of the engine like
> > timing would.
> >
> >
> > Is the (supposed) 30hp gain from the computer merely from advancing
> > the
> > timing and a richer mixture at WOT, or is there more? As far as the
> > timing
> > goes, is it advanced X degress across the board, or did they actually
> > alter
> > the shape of the timing curve?
> >
> > Here is the reason I ask... I have been doing a lot of aftermarket
> > ignition research lately (trying to hash out a plan for a nitrous
> system),
> > and in my travels, I came across the Holley Pro Strip Annihilator. This
> > ignition actually lets you program your own timing curve. Here is a
> > snippet from their web site:
> >
> > >>>>>>>>>>>>>>>>
> > Fully Programmable Timing Computer - Program a 32 point
> > timing curve from zero to 50° (in 1° increments) from 500 RPM
> > to 16,000 RPM (in 500 RPM increments). Max. timing span is 34°.
> > Timing is accurate to within ±1/4° from idle to 16,000 RPM.
> > <<<<<<<<<<<<<<<<
> >
> > You can probably figure out where I'm going with this... If most of
> the
> > performance is merely from the timing, could you just slap this ignition
> > on
> > there and program in a similar curve? (With this method, you could even
> > program in a custom curve to meet your unique requirements; you wouldn't
> > be
> > stuck with the MP one.) Get a set of high flow injectors and now you've
> > got a richer WOT, just like the MP PCM...
> >
> > What do you think? Is it that simple, or is there more? I was
> thinking
> > that if this would work, it might be an option for you '97+ folks that
> are
> > waiting for computers.
> >
> > The one big drawback to this method is that, even *if* it does work,
> > this
> > particular ignition is in the $500 neighborhood. (Jegs has it listed
> for
> > $559.99) Figure another $200 or so for the high flow injectors (for the
> > WOT fuel increase), and you're looking at almost $800 to simulate a $250
> > computer, but I guess if you're desperate enough... :-)
> >
> > Any thoughts on this? Feasable, or is my brain running a few volts
> shy
> > of stoch? :-)
> >
> >
> > -Jon-
> >
> > .--- stei0302@cs.fredonia.edu ------------------------------------.
> > | Affiliations: DoD, EAA, MP Race Team, NMA, SPA, USUA. RP-SEL |
> > | '96 Dodge Dakota v8 SLT CC (14.58@93.55), '96 Kolb FireFly 447 |
> > `----------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
> >
> >
>
>
>
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