Re: TB mods ?'s for flyboy01

From: Mark Kuzia (flyboy01@worldnet.att.net)
Date: Wed Jan 13 1999 - 18:29:39 EST


Sorry if I got that one wrong (O2 sensor), this info was from a friend that
works at a local speed shop. I never had a problem on my 5.2L, he claims
that he did with his 5.9L. Correct me if I'm wrong, but I read in Mopar's
"Magnum Engines" book that the OBD-II system works in both open and closed
loop modes at different times. I also heard that 5.9L's had a lean problem
on the #5 cyl when the exhaust flows too freely and the solution was to get
more air into the engine which forced the injectors to fire for a longer
time (is this correct or am I wrong?). I'm still learning, if anyone can set
me straight, its O.K. Please comment if anyone understands what we are
debating.

On the Idle set screw, I removed a little too much material and had a very
high idle. The only way to correct it was to remove the cap. THIS STEP DOES
NOT HAVE TO BE DONE IF YOU ARE CAREFUL! I was not. Besides, smog checks are
a good reason to have a spare TBI.

The bore and the blades are 50mm, but the bore closes up to about 48mm near
the center (progressive bore). V-6 t-bodys are 46mm. I tried to keep the
bore the same at the butterflies.

Mark
 http://home.att.net/~flyboy01/

-----Original Message-----
From: mike.burgess@akamail.com <mike.burgess@akamail.com>
To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
Date: Wednesday, January 13, 1999 11:55 AM
Subject: DML: TB mods ?'s for flyboy01

>I went to your WWW page, http://home.att.net/~flyboy01
>and looked at all the cool stuff you have there, but I have a ? about one
statement
>on your main page about the O2 sensor:
> 3. Don't do the exhaust yet, the stock system flows plenty of air for
now.
> Port your throttle body. Get more air into the engine first before doing
> exhaust mods, this keeps your engine from getting a lean signal for the
> O/2 sensors. The throttle body made the biggest difference in overall
> power from the engine.
>I don't understand what you are trying to say here. The O2 sensor (when in
>run/hot/closed loop mode) trys to keep the "ideal" ratio. This shouldl be
under
>computer control all the time, and that's why we are able to make mods
>(within the limits of the computers range, and the injectors capacity.) I
would
>think that since the stock injectors are at about max flow at WOT, adding
more air
>WOULD make it leaner, once the injectors are at their limits.
> Also on your TB mod page, here in Kalifornia, the AQMD checks the seal on
>the idle screw, if it's gone, you fail smog, and loose the $ cap on
repairs.
> If after the mods, there is more air getting past the 46mm butterfly, at
the
>50mm bore (6mm of air gap), I would think that the butterflys would need to
>be replaced with 50mm., not adjusting the idle screw.
>
> Hmm, how is this handled with Bruces stage ll (which I have on
order),
>Bruce, is it really a drop-in, or does the idle screw need to be tweaked?
>
> Anyway, I'm open to all sorts of ideas, I just need to understand them.
>I'm still mesing with a Jacobs inig system, and opening up my spark gap,
>I should have been getting better mileage, but I don't seem to see it. Just
>did a road trip to AZ this weekend, held it back to about 68MPH both ways,
>and my mileage was only 17.6MPG That's about what I got at 75mph.
>
> Anyone got the console with the mileage computer in it, would you do a
>run on your next road trip, a couple of miles at 55, 60, 65, 70, 75, 80
mph,
>and try to get a charting of where the MPG peaks at?
>I have 318, 4p auto w/od, 3:55 rear axle 2,000 RPM's at about 68 MPH
> Mike
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