Exhaust fumes smell different...why?

[TheTSiGuy]

I've noticed that my exhaust fumes dont smell normal at all.

Why is this? is it possible to smell running lean?

Its not rich, i dont think. I have 550s, a walbro fuel pump, and a 2g maf as far as fuel stuff goes. My AFC isnt really tuned, so its hi throttle position is set to zero across the board, and about negative five on the low throttle.

Any ideas why this may be? what makes the exhaust fumes smell different?

 

[FearceDSM]

I would think that you are running rich with that setup w/ the afc settings. 550 injectors run 22% more fuel than 450's, so in order for you to be back to stock fuel delivery, you would have to lean the afc out more than zero at hi and -5 at low.

 

[TheTSiGuy]

ah, but remember, i am running the 2g maf, which flows 20% more air. So it cancels out the 550's

So if im running rich, it'd be ever so slightly.

Any other ideas? i think i'd know what running rich smells like, right? like a snowmobile or something dumping fuel?

 

[FearceDSM]

I guess that could describe running rich. Also, your exhaust sounds slightly deeper. Which pump are you running to be specific? Is it rewired? Do you have an aftermarker AFPR? I have read around about 1g owners having issues using the 2g MAS. Do a search. Maybe your situation isn't uncommon. Good luck and keep this thread updated