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What size throttle body do you use (diameter or type),
Chris?
What I would speculate (and this is all it is) is
that when you throttle down suddenly - the engine manifold pressure drops
rapidly - IF your manifold pressure sensing hoses to the EC2 are too small or
there is too much damping of the manifold pressure signal for other
reasons, then your engine could be down operating at lower manifold pressure
while your fuel injector is still calculating fuel for the higher manifold
pressure it is still seeing. So your engine could be running overly rich
for a period of time.
Throttling down slowly gives the manifold pressure read by
the EC2 to adjust to the engine manifold pressure as it is slowly reduced and
you avoid the mismatch due to manifold pressure differences.
There could also be some mismatch between your fuel
map and operational needs. But, again these are just guesses based on the
limited amount of data.
The easiest way I know to check the manifold pressure
sensing possibility is to try putting on larger manifold hoses running to
the EC2/3 or removing any damping cans or such..
Ed
Sent: Tuesday, February 21, 2012 10:53 AM
Subject: [FlyRotary] Throttle Back Bobble
When I throttle back on my otherwise smooth
running 13b turbo, I tend to get a bobble
(miss?) as the engine spins down. I don't seem to have it if I throttle
back very slowly and smoothly, but fast moderate (usual manner) or quick
throttle back produces it. I have noticed this
on Lycoming's if throttled back quickly,
but obviously not an issue that I have noted in a regular car
engine.
Just curious if others have had this occur and if so why.
The list has been especially quite lately so come on folks, here your chance
to shine before I start calling DAR's ;-)
Chris
Houston
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