Strange power drop off
06-20-2015, 07:41 PM
#1
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Strange power drop off Just got my automatic in and frost tune. Cars doing the same thing it did with 6 speed. When I go WOT, it feels like it's down 150hp, then it will all of a sudden start pulling hard like it should. Feels like nitrous engaging. Then after the shift, it will lay down again, then pull hard again. I know I need to get a wide band on it. I don't know if air fuel would cause that tho. Could it be sensing knock and retarding timing? I'm so tired of fighting this issue. Help!!! Haha
06-22-2015, 02:02 PM
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Serious knock retard, though, would be. LO table use
is not going to come and go abruptly however; it's
interpolated-to based on the slow moving Knock
Learn Factor.
A transient lean condition is one way to get into a big
knock-retard divot. False knock is another (esp if you
have a noisy valvetrain or exhaust banging that rings
the heads and gets picked up).
is not going to come and go abruptly however; it's
interpolated-to based on the slow moving Knock
Learn Factor.
A transient lean condition is one way to get into a big
knock-retard divot. False knock is another (esp if you
have a noisy valvetrain or exhaust banging that rings
the heads and gets picked up).
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06-23-2015, 10:32 PM
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I would begin with scanning to see whether this is it.
Log all of the spark advance and retard modifiers that
roll up to the main advance, see who's bugging.
On the 4th gen F-bodies the knock attack rate is higher
than I like (mucho KR for just one blip, worse with many)
and the decay rate too low (hangs around for too long).
This makes it hard to really even see what's going on
after the first hit, makes spark histograms kind of
useless for fine-tweaking the advance map. I halve the
attack and double the decay. You will still have KR when
you need it, just not the excess so much.
Now I would not entirely rule out a converter issue
without driving the vehicle. My converter has a brief
"who, me?" when I mat it, and then decides to pull.
Could be yours is more of the same. Converter that
isn't slipping, isn't multiplying torque and maybe this
is what you feel. Might look at the TCC slip RPM and
the trans delivered torque, see if slip follows torque
or takes some time to come around maybe. No idea
why this behavior exists, only observe it on mine and
not bothered enough to dig deeper.
Log all of the spark advance and retard modifiers that
roll up to the main advance, see who's bugging.
On the 4th gen F-bodies the knock attack rate is higher
than I like (mucho KR for just one blip, worse with many)
and the decay rate too low (hangs around for too long).
This makes it hard to really even see what's going on
after the first hit, makes spark histograms kind of
useless for fine-tweaking the advance map. I halve the
attack and double the decay. You will still have KR when
you need it, just not the excess so much.
Now I would not entirely rule out a converter issue
without driving the vehicle. My converter has a brief
"who, me?" when I mat it, and then decides to pull.
Could be yours is more of the same. Converter that
isn't slipping, isn't multiplying torque and maybe this
is what you feel. Might look at the TCC slip RPM and
the trans delivered torque, see if slip follows torque
or takes some time to come around maybe. No idea
why this behavior exists, only observe it on mine and
not bothered enough to dig deeper.
