Jon,
One thing I like is there are hundreds of ways to accomplish the same
goals, it just takes understanding. Since you have me thinking about
this, I might as
well start working on it. Bill made a post earlier on the subject and he
said that there was a test (larger TB on a V-10), with a loss of low end
torque. I really want
to avoid this. I'll take one of the stock TB's and flow it at different
throttle plate settings. Once done, modify the TB and shaft to accept
the larger plates and
flow it again noting the differences in throttle position to get equal
flow rates. Hopefully I'll be able to re-clock the TPS (more than likely
a new throttle shaft, offset
engagement into the TPS) so that we get the same output voltage at equal
flow rates except for WOT. This should cure the loss of low end torque,
and will
only leave WOT. If it turns out that WOT is not rich enough to
accommodate the additional air, then it will be time for a custom chip
to handle the air. I'll start
playing.
Frank
> -----Original Message-----
> From: Jon Steiger [SMTP:stei0302@cs.fredonia.edu]
> Sent: Wednesday, August 19, 1998 12:34 AM
> To: dakota-truck@buffnet.net
> Subject: RE: DML: RE: Throttle bodies again.. (was: 98 R/T power
> mod's que stions)
>
> >Jon,
> >A lot of info here. You are right the TPS just measures throttle
> >position (generally a voltage from 1 to 4 or 5 volts, closed to
> open).
> >If you open up the
> >throttle bores, you are allowing additional air to flow to the engine
> >and the TPS is generally used to determine how far your foot is in
> it.
> >If you are in closed-loop,
> >(the engine is looking at the sensors and pulling values from the
> fuel
> >and ignition maps, you could end up with a lean condition or worse
> yet,
> >the values between
> >the sensors may be so mis-matched that you get a "Check Engine"
> light.
> >This is all based on the strategy the Powertrain programmers have
> >programmed into
> >the computer (and it is classified). The values in the "look up"
> tables
> >are all based the total powertrain package. The programmers generally
> >don't take into account
> >and individual installing a TB that flows 30% more air then the
> >original. They do take into account temperature and altitude
> variations.
>
>
> Hmmm... Do you think the temperature and altitude compensation
> would
> be enough to make up for the extra air? That is, feeding the PCM a
> lower
> than actual intake temperature and/or a higher than actual pressure
> (is this the MAP sensor?), would, I assume, trick the PCM into
> supplying
> more fuel for the supposedly denser air?
>
>
> >My goal would be to provide
> >additional fuel for the additional air, throughout the entire RPM and
> >power range, not just a WOT.
>
> Yep, that sounds like a good idea. Assuming the already slightly
> rich
> condition at WOT is enough to compensate for the extra air, I would
> think
> that the rest of the powerband is all you'd have to worry about.
> (Except
> for idle; I don't think that would present a problem.) However, if
> the
> WOT condition isn't rich enough, providing extra fuel when the
> computer
> stops looking at the sensors and goes to the lookup tables might prove
> interesting. :-)
>
> > By looking at the exhaust before the
> Cat, I
> >can tell if I have a
> >lean condition.
>
> You may already have a method of doing this; if so, just ignore me.
> :-)
> I just wanted to mention that a good way to do this might be to simply
>
> monitor the output signal of the upstream O2 sensor. Its range is 0-1
> volt.
> If I remember correctly, the more oxygen in the exhaust, the lower the
>
> voltage, so 0 would be 100% oxygen, and 1 would be no oxygen (I
> think).
> Using the existing sensor would save having to cut into the exhaust,
> anyway...
>
> > I wanted to take the easy way out (find someone who
> has
> >already performed the work and just copy the TB mods at a lot less
> >cost),
>
> Heh heh heh! Don't we all! Its definitely worth a shot. :-)
>
> >but I haven't
> >found anyone who has done the dyno work. In regards to some type of
> >microprocessor, I suspect that something as simple as a resistor or
> >re-clock on the TPS
> >would be good enough if there is indeed a problem.
>
> Yep, you're probably right. I tend to think in terms of
> microprocessors
> since my thing is coding and I don't have a lot of knowledge or
> experience
> with circuits and electronics. Usually, when I suggest a
> microprocessor to
> solve a problem, there is a simple circuit which will do the same.
> :-) If
> a processor was required though, they're fairly easy to program and
> relatively
> cheap. ($3-$5 each, with maybe $1.50 extra for the parts to make 'em
> work
> like a clock input and a capacitor) I haven't actually used one of
> 'em in
> an automotive application yet though, but I hear RF and EM
> interference
> can be a problem if you don't shield them right.
>
> > Again I am looking
>
> >for driveability and power, I don't want to loose anything. Once I
> get
> >all of this resolved
> >in my mind and I sure the mods can pass emissions tests, I wouldn't
> mind
> >doing the work for other people. It is really a simple 15 minute
> task.
>
>
> Ahhh, to have access to all of those great tools! :-) I did some
> mild porting with a dremel tool. I'll be interested to hear how you
> make
> out. If the computer is happy with it and its good for some extra
> power,
> I'd certainly be interested in getting mine done.
>
>
> -Jon-
>
> .--- stei0302@cs.fredonia.edu ------------------------------------.
> | Affiliations: DoD, EAA, MP Race Team, NMA, SPA, USUA. RP-SEL |
> | '96 Dodge Dakota v8 SLT CC (14.85@90.72), '96 Kolb FireFly 447 |
> `----------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
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