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A couple basic EFI questions

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Old May 7, 2009 | 11:09 AM
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Default A couple basic EFI questions

Had my turbo motor tuned afr 11.5 +or - a few tenths. Take the car back (same dyno and WB) after a intake and cam change (a little higher lift, very close to stock duration) first dyno pull it went 14.0 AFR aborted run, added more fuel to bring it back to 11.5. when the car went 14.0 afr the weather was about 15 degrees warmer.

My question is this proof that the car is making more power because it's requiring more fuel? I can't use the dyno numbers because the car is a stalled auto and the numbers are all over the place.

Tell me if this is correct, with the intake and cam change the pcm will adjust to keep the afr correct during idle and cruise but during full throttle it uses a different set of parameters or goes open loop? I'm a EFI newb, after the cam and intake without the new tune it ran fine during idle and cruise.
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Old May 7, 2009 | 01:02 PM
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Do you still have a MAF on this setup? Yes the car will, to a point, trim the fueling to get you to the stoich area in closed loop which is idle and part throttle. It sounds like your getting a decent amout more air getting into your setup and it's leaning out your setup.

On WOT runs you go into open loop and the MAF will take over along with your PE table. If you don't have a MAF it uses your VE table value for that cell and the PE multipliers.
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Old May 7, 2009 | 01:47 PM
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Yes it still has a MAF, so at wot the pcm doesn't see the extra air and adjust fuel in simple terms?

Also if my combination is requiring more fue to keep the same afrl after the changes than would it be safe to assume it's making more horsepower?
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Old May 7, 2009 | 07:50 PM
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