Thread: VF570 installed
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      12-15-2012, 09:38 AM   #83
Beedub
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Drives: 2007 Z4 M roadster vt2-500
Join Date: Sep 2007
Location: UK

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Quote:
Originally Posted by pokeybritches View Post
Nothing was defective, and this was an OBDII car... albeit a 1999. The engine was brand new.

Maybe it comes from my aviation days, but I never rely on computers to automatically tell me whether or not something is wrong. They fail, often with catastrophic results. I like having multiple methods of determining the state of operation. The last thing I would do is assume the car is fine just because there's no OBDII code thrown.

"Too lean" has a different meaning once you add FI. The car may not be programmed from the factory to throw a code until the AFR reaches a certain value, but detonation can occur prior to that due to the extra heat introduced by the supercharger. Optimum FI AFR's, and what the car thinks it should see when naturally aspirated, differ. I'm admittedly new to the FI world, but I do know that nearly every tuner wants an AFR around 11.5 at WOT. I don't think anyone wants to see 14.7 at 8000 rpm on a FI car.

I know that ESS said the VT550 would require a fuel pump upgrade, and the dyno that was posted showed the car running progressively leaner as it approached redline. I've seen firsthand what happens when the fuel pump is unable to provide adequate fuel, and there was no OBDII code thrown. I haven't seen any proof that the Z4M is capable of a claimed 570 hp without a fuel pump upgrade. Rated M is the first on this forum to do this, and with that comes risk. I'd pay attention to what that graph is telling me. Right now AFR's are leaner as the rpm climbs (right where detonation would be most catastrophic), and I wouldn't assume everything is good to go because the tail pipe sensor was sniffing the exhaust after the secondary cats had done their thing. I'd take the conservative route and not rev over 6500 rpm until you confirm that the fuel system is up to the task. After all, it is an increase of 60% over stock.
honestly????? i think ALL Tuned cars with Fi wether stage 1 or 3 or whatever should be running an upgraded pump.
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