>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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