-----Original Message-----
From: Dak99RT@aol.com <Dak99RT@aol.com>
To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
Date: Sunday, April 18, 1999 6:06 PM
Subject: Re: DML: Re: IAT sensor
>In a message dated 4/18/99 6:13:01 PM Eastern Daylight Time,
>tomm@datarecall.net writes:
>
>> The guy told me of another cool mod-ever wonder why your truck runs so
>> good in the morning?(when cold). I always assumed it was because our
trucks
>> just liked the colder air. According to this gentleman, it's because of
the
>> water temp sensor-being cold on startup! He said to wire up a
switch(like a
>> double pull one- I think) can put an additional sensor in the washer
fluid
>> bottle and switch to that one when racing. Kinda like a N2O switch-he
>swears
>> it really helps, even more than the IAT mod.
>
>
>I would think that would just be the same as having a 160 degree
>thermostat... it would make the truck stay on open loop. No? Running real
>rich. Wouldn't that make for an incomplete burn and less compression thus
>less horse power?
> I would think the reason you run better when the motor is cold is
>that the computer is in open loop... thus it is running off the computers
>fuel tables that don't change. They have them set this way so the motor
will
>never run dangerously lean until it is warm enough to go into closed loop
>where the O2 sensor takes over. So when the motor is cold it breaths colder
>air with its higher oxygen content, it better matches the open loop's rich
>fuel table. This makes for a better air/fuel ratio... more oxygen, more
fuel,
>more power hmmm sounds like a tiny nitrous oxide system : ).
> Also on the IAT sensor... you can find a rheostat that will have a
>variable ohm load. Once you find the magical impedance you can just read
the
>rheostats impedance and go out and buy the correct resistor. Instead of
using
>trial and error with a bunch of resistors. I'd be interested if it works as
I
>have never heard of that one before.
> I owned an 11 second 87 Turbo Buick that used basically the same
>motor as the 89 Turbo Trans Am. I had never heard of that screw you are
>talking about on the MAP sensor that can vary the fuel curve but, it is
>possible.
>Charles
>
I'm not going to pretend to have the knowledge some of you do on this
computer stuff, but I've just been told that it does indeed work. Reasons
are up for debate. In theory, a richer mixture wards off detonation while
sacrificing power. My guess is that all the mods are starving the motor for
more fuel and the rich condition on startup assists in remedeying this.
However, I do remember my buddies trucks also running better on startup when
they were completely stock so go figure.
In any event, this is an area that REALLY needs to be explored; esp.
by some of you guys with good electrical experience. Lets face it, our
trucks are not "mass air " so we have a lot of hurdles to overcome with the
speed density system. More mods=more problems. A lot of you guys are already
exper. "pinging" due to advanced timing and fuel shortages. Anything we can
do to increase the inj. pulse width the better. I'd have gotten started
already, but my motor is STILL in the machine shop! I know there is a lot of
smart cookies reading this who could make it happen; or we could wait and
see if Jules will give us any of his "secret" tips-- anyone in need of a
$2000 throttle body??
Tom(11s dak)
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