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[alfa] '82 GTV-6 rev limiter: still there
I finally got around to modifying my spare ECU in an attempt to get
rid of the 6400RPM rev limiter. Believing what I'd read on
http://home.swipnet.se/joakim_adolfson/lotus/html/injection-text.html
(and on the now-defunct site that seemingly inspired it), I lessened
the resistance of R106 to effectively zero by shorting R106 with a
piece of wire. The result was a car that wouldn't start, seemingly
for a complete lack of fuel. I thought maybe I'd damaged something,
but sure enough, when I removed said short, it started normally. So
I suspected that perhaps it needed a non-zero value of R106 to start.
I don't remember the exact numbers, but the pair of parallel
resistors that originally made up R106 had an equivalent resistance
of something like 135k ohms, and I happened to have a similar
resistor lying around, so I soldered it in there and got an
equivalent resistance of around 70k ohms. The car still started
normally. I reconfigured my shift light to illuminate at 6600 RPM
(the tach isn't terribly accurate anymore) to be sure of whether or
not I'd eliminated the limiter. When I drove the car today, I revved
it out, and the shift light didn't illuminate before the limiter cut
in. So what's the deal? Is the L-Jet web site wrong? If so, why
didn't halving the value of R106 screw something else up (fuel/air
gauge read the same as always after the modification)? Is it
logarithmic or something such that halving the resistance only moved
the limiter 1000RPM or something? I've been told that '81-83 cars
have a second limiter in the ignition ECU, at 6800RPM--is it possible
that that limiter is also at 6400RPM like the fuel ECU's limiter that
I thought I'd eliminated?
Joe Elliott
'82 GTV-6
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