Re: odd problem

[rdh@sli.com (Robert D. Houk)]

   ...
   As soon as I fixed the switch, the car developed a huge
   loss of power at high revs only (>5000rpm). It can't even make it to
   the red line in 2nd gear, until I lift the gas pedal slightly to open
   the switch, then vroom, normal accelaration, until I floor it again.
   The problem is accompanied by a surging effect, reminiscent of a misfire.
   ...
   I believe the main purpose of the switch is to allow the computer to
   enrich the mixture at full throttle. Anyone know why? Car seems to go
   fine without it.

Generally, running "a little rich" results in more power, and also helps
cool the head/valves a little (and less likely detonation as well). Pro-
perly adjusted and operating, it makes a significant difference ("improv-
ment") in the engine performance.

If your engines runs well sans enrichment, you might well be running way
rich to begin with. On mine, WOT translates to 70-78% fixed open-loop
duty cycle on the FreqValve, rather than the "normal" 40-60% range. If
your engine (more properly, the Fuel Injection Distributor) is running
way rich, requiring the computer to lean it way down in order to run
"normally", then running open-loop enrichment would be way way too rich
and your engine would run like ***t (and probably foul plugs in short
order).

The easy way to check is to hook up a duty-cycle meter (e.g., SunPro 7678
or the like) to the FreqValve. The ideal reading would be 50% -- this
says the FI is spot-on and the computer doesn't have to diddle the base
mixture at all. Typically, you'll see readings varying several percent in
the 40-60% regime. Anything below 40% says the FI is running rich, and
below 30% you're running way rich and the computer is really having to
struggle to maintain proper mixture (and thus WOT open-loop of 70% would
be a disaster).

Or it could be about a hundred other little gremlins conspiring to make
your day...

					-RDH