Big pump blues. Too much fuel = knock Options

[awd4kicks]

It feels rich when I'm riding in it, but after your experiment I would tend to think the opposite.

The Blaha is supposed to make the ECU think the incoming air is very cold, but this is really to avoid over running the MAF and causing fuel cut. The MAF is going to read a certain amount of air no matter what, and with the Blaha your actually sucking in a ton more unmetered air the ECU doesn't know about which should really lean it out. For instance if you didn't have the flapper door on the Blaha it wouldn't idle for crap when it's cold, but when you block some of the air the car runs better with the reduced air and fatter mixture.

This sounds like a good spot for Nate to go engineer on us...