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Discussion Starter #1
hello everyone i am new to the forum
my name is nick and i am from greece
i have a 2002 coupe manual m3
i notice than the powerband of my car was like a Vtec honda not smooth but very poor accelaration till 5500rpm
after i dyno the car i see that when the car hit 4000 rpm the afr goes 15 and come back to normal 13-12 at 5500rpm and pull hard
the car has stuck long term negative fuel trim at -14
i have check and change so far
maf
o2 sensors
tps
fuel pressure regulator
dme
fuel pump
vanos
air leaks
i post the dyno if i find how the forum works :lmao:
 

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If you're making 344 HP you are either FI or have an extreme NA tune. If the DME is not shooting out problem codes then you need to work with your FI shop or DME tuner to fix your AFR.
 

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Discussion Starter #3
the car has racing cats eisenmann exhaust and a bmc air filter in the factory box! i had a tune on the dme but i reprogram the ecu with the stock file to see if the tune was the problem but it's doing the same thing ! dont look the number on the dyno and its hp not whp to have fi just look the curb to see the problem!
 

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So at WOT the car seems to work fine, but under that, not so much (lean condition). Have you checked injectors? That's the only thing I can see that you haven't listed as replaced. I'd suspect a leaky injector or two, but when the pressure gets high enough the fuel flow skips past the leak. Guessing from afar here, but that's what you asked.

The pump would fail at higher pressure and be fine at low, while the injectors are just the opposite.

GL

maw
 

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Yep...definitely midrange lean condition.

That's some 344 whp!

Seeing as a stock S54 is 333 net at the crank from the factory.

But I agree...pull the injectors and have them cleaned or replace them with higher flow injectors and retune.
 
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