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E34 (1989 - 1995)

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Old 01-26-2013, 11:26 AM
Microtesties Microtesties is offline
Unregistered User
Location: Concord, NH
Join Date: Oct 2012
Posts: 101
Mein Auto: 1990 BMW 525i
M20 fuel system upgrades

Hello everyone! So as some of you may know I've been trying to bring my 1990 525i back to its former glory and beyond. I finally have gotten her running just about back to normal, and I'm trying to swap in some performance parts where things need replacing, rather than stock. Currently the car is completely stock except for a 2.7' MAF in place of the AFM.

My fuel pressure regulator was letting a bit of gas into the vacuum line, so I replaced it with the cheapest "OE" part I could find. Come to find out the new regulator is actually not within spec, varying between 38 and 47 psi (should be 40-47). So since the Bosch one is around $100 at the cheapest, I plan on getting the adjustable regulator from IE for $165. I've also been thinking (future) about upgrading from the tiny 1-hole 14lb injectors. Anyway, enough background info.

-What size injector should I be looking at? (I was thinking 4-hole 17 or 19lb)

-Will my O2 sensor be able to cut injector timing enough to keep it from running rich?

-Can I lower fuel pressure to avoid running too rich?

Thanks in advance for your support!

MAF - https://www.millerperformancecars.co...&category_id=6
Regulator - http://www.iemotorsport.com/bmw/E28-...e30adjreg.html
Injectors - http://www.ebay.com/itm/BMW-E36-M3-3...00874888800%26
Year: 1990
Model: 525i
Transmission: 5 speed
Mileage: 250k
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