Re: hello everybody (throttle) ques. for 4.7 daks

From: Bob Tom (tigers@bserv.com)
Date: Thu Mar 01 2001 - 10:43:43 EST


At 06:33 AM 3/1/01 -0600, you wrote:

>Arnoldo Silva wrote:
> > thanks shane considering what you just said how can i fix the problem. and
> > get more power at full throttle diff t-stat or what.

>Man I wish I knew the answer to that. I really would like to continue this
>thread. A redneck method might be to limit the travel of your TPS to just
>under
>what the PCM considers WOT. Thats one of the things I want to try at the
>dragstrip.
>
>Bob (from Canada) - didn't you do some testing at the dragstrip re: this very
>phenomenon? Did you come to any conclusions or have any interesting
>results/tricks/ideas? Thanks in advance, Shane

Hi Shane, Arnoldo.

I was thinking of the 'redneck' method but for different reasons. One
was that scanner readouts done on track runs (strictly WOT) showed that
I was running extremely rich. Not have wide band O2s setup (very expensive)
nor a dyno with that type of diagnosing capability up here, I suspected that it
was richer than the approx. 12.5 range at which max. power is produced.
A phone call to Zimmer in CA kind of confirmed this suspicion but even he
could not give me an approx. afr from the pulse width voltages that I gave him.
He just said that it was pretty rich. As far as I can tell from my web
searches,
my afr is probably around 12.0:1 at WOT.

As far as the phenomenon with the throttle, I think that it is because,
when the PCM senses a quick/sudden full throttle condition from a sudden,
drastic
change in TPS signal, it makes a momentary enrichment in the afr as a safety
precaution and, possibly, retards the timing a bit as well. Once the PCM
figures what's going on, the MAP signal plays a larger part and the TPS
signal plays a lesser in the pulse width adjustments. At least from what
I've read, that seems to be the common strategy that is adopted. I know
from my dyno runs, no matter which PCM I used, a blip (drop) in rwhp and
torque for a split sec. happened at 4300 rpm.

As far as solutions, I think that you either have to have the PCM reprogrammed
or test and tune, if you have the necessary equipment and some knowledge,
by manipulating the TPS and the MAP signals.

As for reprogramming, all delays would have to be removed and timing
advanced a bit with enrichment lowered a bit in the WOT tables. There goes
the safety factor:-) Question for me was: would I spend the $500 U.S.
(currently over $750 CDN) without knowing what the approx. gain, if any, would
be in the 1/4. For a retiree, the answer was obvious.

Hope this enlightens or provides food for thought. Keep the threads coming.

Reading with interest.
Bob



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