[WraithX]

Need some search help here. I can't (for the life of me) find the post that Tephra made regarding one of the Cylinders being annoying at super high WHP, and how he wished there was some way to get individual widebands to measure and tune each cyl's AFR.

I'm looking at doing some more shit with the VMC I have access to, and I was trying to think of some way to modify the fuel system so there's consistent fuel pressure to each of the cylinders regardless of their position on the rail, to eliminate issues.

 

[HappyMint]

It's cylinder #4 that I'm sure he was referring to. There are multiple failures linked to a lean condition in cylinder #4. Most theories generally indicate that the intake mani flows more to cylinder #4, though there hasn't been any real conclusive testing regarding this theory, and as far as I know, there are no benchmarks showing flow of the stock intake mani. There are benchmark flow #'s for MAPs rev 3 intake mani though. I haven't heard that there may be less pressure on the fuel rail for cylinder #4 but it's an interesting proposition. There still isn't anything preventing anyone from monitoring the AFRs in the exhaust mani for each cylinder outside of some custom fab and some $$$.

I'm not sure if there have been cylinder #4 failures linked to a lean condition with an aftermarket fuel rail or not, but I suspect there may have been.

 

[WraithX]

I mean it seems entirely plausible. 4CYL would get the most air pressure and the least fuel pressure (I know air and fluid dynamics are different, but the same theory would probably apply for both.) The combination of the two could lead to the lean condition, and the regulation of the fuel pressure could help compensate for the increase in airflow.

 

[Golden]

HappyMint, MAP did flow testing of the manifold. Look on their Rev 3 Intake manifold porting page:
http://www.maperformance.com/maperf...nifold-mitsubishi-evo-x-map_evox-im_rev3.html

Note that #4 is does not flow the least. #1 and #3 have an 8% difference.