Engine running lean. what's causing it?
 

https://www.evolutionm.net/forums/sh...d.php?t=135775

that's the dyno graph with the a/f.

I have Turbo back exhaust without cat, (3'') that has 2 resonators built into it.

MBC, 21 psi daily.

stock everything else. stock ecu, never been flashed... except for the dealership flash to get rid of the p0300 misfire bs.

Now, I'm running that lean, what could be the problem?

injectors, fuel pump, spark plugs, ignition coils? what the hell is causing this?

I have 40,000 miles on stock plugs so far. Those iridium stock plugs are good for 60,000 miles. anyway...

I did get a dealership flash, but I was suspecting they didn't know what the hell they're doing, since they were refering to the manual.

anyhelp would be great.

If you have another dyno sheet before the dealer flashed your car, that would definitely help. But I figured you might not. It is definitely way lean, it is way to aggressive especially if you drive your car on a daily basis. Be careful with the type of gas you put in there until you get reflashed and/or add higher cc fuel injectors and fuel pump. Also if you have an AFC or some other type of fuel control tool, try adding fuel across the whole RPM band until you get someone to reflash it.

In regards to the spark plugs or anything related to the ignition causing how lean you currently are, it is not likely. If your ignition system was failing (spark plugs, coils/wires) you would know it. It would be missing all over the place. Also the Evos ignition set up has only been known to run into problems when running more than 25+ psi or you are using/used the Greddy E-Manage. Which has been known to burn stock Evo coils. Plus the run would NOT be that smooth on the dyno graph you posted up. If anything, it would show up rich since there is no spark to ignite the combustion cycle.

what octane gas are you running?

also, fuel pump is more then likely maxed out too

93 octane, bp gas. Never had problems with it, my tuner said it's not the gas.

Only thing I could think of is that damn dealer flash.

I don't know if they could load an eclipse map on there or do something to slow the fuel down or something...

if the maf sensor was damaged, i would know. (graph would be all over the place.)

so I just don't get this crap at all.

what does your timing look like? do u have a log of it by chance?

While way too lean, that A/F graph is smooth as it can be. Did anyone else besides Mistu ever flash it?

huh? So you're running stock tuning but on 21lbs? Or did you have a flash, and then the dealer flashed over it?

I must be missing something here.... because 21# and the lower restriction on exhaust is going to lean yah out...