Originally Posted by suterp
Any theories about why the newmission mod would hurt performance in the city? Seems like more cool airflow would be a good thing but I hesitate to cut open my airbox when some are reporting no gains or worse.
I wish I could say I knew, but unfortunately I don't. I only have two thoughts on it-
A. The direction of the forced airflow causing turbulence in/at the filter. By this I mean that, at low speeds, the air is causing turbulence directly in front of the MAF sensor, causing confusing inputs for fuel injection. I have contemplated building a shroud to divert the air around the filter as opposed to directly at it to see if this is it/helps, but haven't because BUSY/LAZY. I think that this is only causing the low speed issues because at some unknown (by me) speed there is enough air being forced into the intake to overcome the engines air intake requirement, in turn creating a mild boosted (in the box) condition in which the air is readily introduced past the MAF sensor smoothly. In my head, this explains the loss at lower speed and increase at higher speed.
B. It isn't uncommon for vehicles to see an mpg reduction after the installation of an aftermarket intake due to the car being programmed based on a stock intake. The additional fuel has difficulty exiting a stock exhaust, and all of the dynos on OEM exhaust have shown that the exhaust is very near max flow capacity straight from the factory. This is why the majority of mpg seekers go straight to the exhaust, as gains are almost always seen immediately on them, even with a stock intake.
This is really all I can think of based on my knowledge/experience base...