Author Topic: my supercharged M42... issues (Read 10319 times)

B318M42W · « **Reply #15 on:** October 09, 2010, 06:09:35 PM »

Got some progress!! I got her to "idle" properly when the AFR is in the correct range.

I know a lot of you are wondering why the engine even started with 40# injectors in the first place. Barrie from midnight tuning help enlighten me: I have the LC-1 WBO2 kit installed and apperantly it can somewhat trick the ecu into dumping less fuel.

This sparked the idea of vacuum leaks. unmetered air entering the engine along with extra fuel would result in a better AFR, higher rpm (idle) and a wondering idle. Soapy water revealed massive quantities of air leaks. took it apart and back together with an extra care to avoid any leaks, fixing any holes in the fabbed manifolds. No air leaks this time. The result: a really rich start, to the point it won't idle unless i play with the fuel pump (on/off), when turned off, the AFR gets leaner, engine runs smoother, nice idle when AFR is around 12-15:1 then idle goes to hell when fuel pump is just momentarily on and AFR goes back to 9:1. will post a video shortly.

So now i'm starting more and more to think that i wasn't so crazy to try and see what would happen with stock fuel system. pretty sure i would of gotten a nice steady idle if it wasn't for the massive vacuum leaks. No boost at idle, -20"Hg PSIG

conclusion: check for vacuum leaks before doing anything, even if you're positive there ain't any.

bmwconnect · « **Reply #16 on:** October 10, 2010, 01:18:03 PM »

Yes this is true the LC1 can simulate a narrow band signal when correctly programmed and wired up witch will allow fuel to be pulled but the computer can only pull so much so the car will still run very rich foul plugs quickly and thin oil out... standalone or tune is the only way to solve the problem

bmwconnect · « **Reply #17 on:** October 14, 2010, 12:38:32 AM »

Thanks for making the long trip!! cool setup and car runs mint with your new tune!!
have fun!!

B318M42W · « **Reply #18 on:** October 14, 2010, 12:47:59 AM »

It was well worth it! The car drives great, smooth idle and hard pull all along the rpm range. this guy knows how to tune a car! Really great to work with too. Lots of support before and after the tune also, wich is a really good thing. I highly recommend using his services for any tune.

thanks again!