Car goes lean, at slight "tip in". HP SD tune
08-11-2006, 12:16 AM
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Car goes lean, at slight "tip in". HP SD tune Car goes very lean and bogs bad, only at slight tip in. No matter what rpm. After that it is fine. Any help guys. 9:1 compression 347ci.
Thanks
Bill
Thanks
Bill
08-11-2006, 08:41 AM
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Check for PE delays and enablers. I think some cars came with a delay into PE. Also on modified cars, I like to drop the TPS% PE enabler so that PE comes on sooner.
08-11-2006, 08:59 AM
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Suspect you have a lean dip on the air surge
being followed by a ping burst and knock
retard. Knock retard will persist for a good
while at stock settings. If the speed density
tune is dead-on there is not much you can
do to cover the transient leanness. But you
can use burst knock to settle down the ping
until the mixture is back on plane, or you can
bring in PE early, or you can make the VE a
bit fatter than "ideal" to give you some mixture
margin, or you can take some base timing out
that maybe you don't need in low to mid throttle
regions except for "responsiveness".
Follow the chain of events in the logs (maybe
easier to see all laid out in Excel, than all the
pretty squiggles; depends on your style of
understanding things).
being followed by a ping burst and knock
retard. Knock retard will persist for a good
while at stock settings. If the speed density
tune is dead-on there is not much you can
do to cover the transient leanness. But you
can use burst knock to settle down the ping
until the mixture is back on plane, or you can
bring in PE early, or you can make the VE a
bit fatter than "ideal" to give you some mixture
margin, or you can take some base timing out
that maybe you don't need in low to mid throttle
regions except for "responsiveness".
Follow the chain of events in the logs (maybe
easier to see all laid out in Excel, than all the
pretty squiggles; depends on your style of
understanding things).
08-16-2006, 08:48 AM
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Originally Posted by Bill @ Hi-Flo Turbo
Car goes very lean and bogs bad, only at slight tip in. No matter what rpm. After that it is fine. Any help guys. 9:1 compression 347ci.
Don't use the narrow-bands to do this, and don't be lazy and use the auto-tune function. Getting every cell to run at stoich is NOT the best idea and will leave you lean under load.
Using PE to cover increases in load during normal driving is also NOT the best idea.
08-16-2006, 11:38 AM
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What fuel pump are you running? It could be as simple as a pressure drop. I would hook up a fuel psi gauge at the rail 1st and monitor that. If then you rule out the mechanical side, follow Jimmy's suggested line of thinking.
