E46Fanatics - View Single Post - 325i engine with 330i engine?
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Old 01-17-2013, 10:02 AM   #67
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Join Date: Aug 2012
Location: Texas
Posts: 162
My Ride: 2003 BMW 330i
Originally Posted by TerraPhantm View Post
You are almost certainly running lean. Get the 330 injectors and 330 MAF.

330 tune is programmed with larger injectors in mind. So it fires them at durations intended for that specific size. If you were to install smaller injectors, it'll still open the injectors for the same duration. Net result is less fuel. The restriction of your current intake setup is not enough to account for the reduced fuel.

Further more, the 325 and 330 MAF almost definitely don't have the same calibration. So the DME thinks its getting X kg/h, while in reality it's getting Y.

Basically your engine has no idea how much air and fuel it's getting. As you can imagine, those are very important parameters to running an engine. It can correct based on lambda values, but that'll be less than optimal. Also the lambda is ignored at WOT -- so your car can be downright dangerous to drive at full load.
ok i wont WOT it, so leave the normal intake on? i have a buddy that blew his 330 and got a whole engine for his and he has all the stuff i can grab the maf, injectors and intake.
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