Suggestions for Adjusting WOT fuel?

[Bruce Plecan]

----- Original Message -----
From: Roger Heflin <rah at horizon.hit.net>
To: <diy_efi at esl.eng.ohio-state.edu>
Sent: Wednesday, April 07, 1999 12:19 PM
Subject: Re: Suggestions for Adjusting WOT fuel?

Couple things,
  Knock is real, no two ways about it.  May be a false indication due to
poor electronics, but to accurately tell if you have knock, means pulling
plugs, unless you have an ionization detection unit running.  Even saying
you don't hear it means just that there is no audible knock.
  You can always run first gear leaner then the rest.  With the additional
gear multiplication of the tranny you can't develope AS much heat as when in
the higher gears.   Heat meaning engine load.  Any one who has put too much
gear in a stock motored car can tell ya about how lame they can get..
  Once tuned you can use the O2 as a rough indicator of all's well.  But,
that still should be supported by reading the plugs...........
  You can (any one really) can screw up the tune up to not generate audible
knock, and kick the rings out of it...  With the better exhuast valves, that
fuse is no longer around.  Again, IMHO.
  EGT doesn't tell you anything about the level of tune that your dealing
with.  Just how close you are to the thermal limits of you engine.  Meaning
you can have a rocket at 1550dF or a pig at 1550dF.  Depending on the depth
of your wallet sets the limit of EGT temp, and experimenting at what the
limit is for your engine.
  The trick to tune-up is actually measuring what your doing in performance.
Yes, Doc, I know it's time for my meds now
Bruce

> > Roger,
> > It's all going to depend on your O2 sensor as to what voltage is safe
for
> > you...
> > I was talking with someone last night that had 3 different O2 sensors
(new)
> > that all read different but within about a 100mv range of each other for
> > the same conditions...
> > Is it safe to assume that when you get lean enough to do damage the
engine
> > will knock? if not you'll need an Exhaust temp guage.
> I don't think I will knock, I have a pretty big cam, and it has never
> knocked before (well nothing identifible as real knock, just false
> knock).  I guess if I want to be safe on the knock I cna mix some 100
> unleaded with my gas, and then it won't knock.  The way I determine it
> was false knock was I ran 1/4 with normal gas, and a 1/4 with 50% 100,
> so there was no way it should have knocked, and it still knocked at
> exactly the same points.
> That was what I was worried about.  I have two identical (well as
> close to identical as possible with electronic sensors) bosch sensors,
> and reducing fuel was not changing the O2 values, and it was speeding
> the car up (it should start not speeding up anymore when I start
> getting close to 12.5:1).  What kind of ratio are we talking about to
> be too lean ?  Any ideal what ratio is bad?  Would stoch (14.7:1)
> cause problems?
> Where would someone buy a EGT sensor?  I figured I might in the
> future, get a pic with a A/D, and program it to sample the A/D's and
> also program it to read out the GM computer, and button that up into 1
> serial data stream (probably 19,200 baud) and send that to a laptop
> for futher processing.
> Roger