Originally Posted By: Steve S
Originally Posted By: BuickGN
Originally Posted By: Kestas
That's my argument as well. With fuel injected engines and O2 sensor feedback regulating the air/fuel mixture, a dirty air filter only affects top end performance. If you don't need that "edge", there's nothing wrong with getting your full money's worth from the filter.
Agreed. I don't put nearly as much weight behind airfilter changes as I once did. As long as the media stays in good shape, I don't have a problem running it for a long time. I use WOT once a month maybe and this particular car has more media area than it needs so it would have to be pretty dirty to affect wide open performance. I like how many people will post the 2-5mpg jump going from a clean stock filter to a drop in K&N.
What really should be the question at this point is how far can the ECM compensate for the change in the air flow restriction?
That's the thing, there is no change in air flow restriction to compensate for. For the most part the throttle-body determines the restriction and the intake tract pre-throttle body might as well be invisible. Under some circumstances like WOT and a dirty filter there may be some restriction but it's no different than a partially closed throttle. In a MAF car it shows less airflow. In a speed density car it shows up as more manifold vacuum.
There's the very small and I mean small chance that the car puts a lot of weight on the TPS position, much more common on speed density cars and you may have a slightly richer mix the first time you go WOT if you were to swap a clean filter for a dirty filter assuming it poses a restriction. However the 02 naturally takes care of this as the filter ages with short and long term fuel trims. For most cars, even if there was no 02 feedback it would not cause a rich condition.
Originally Posted By: BuickGN
Originally Posted By: Kestas
That's my argument as well. With fuel injected engines and O2 sensor feedback regulating the air/fuel mixture, a dirty air filter only affects top end performance. If you don't need that "edge", there's nothing wrong with getting your full money's worth from the filter.
Agreed. I don't put nearly as much weight behind airfilter changes as I once did. As long as the media stays in good shape, I don't have a problem running it for a long time. I use WOT once a month maybe and this particular car has more media area than it needs so it would have to be pretty dirty to affect wide open performance. I like how many people will post the 2-5mpg jump going from a clean stock filter to a drop in K&N.
What really should be the question at this point is how far can the ECM compensate for the change in the air flow restriction?
That's the thing, there is no change in air flow restriction to compensate for. For the most part the throttle-body determines the restriction and the intake tract pre-throttle body might as well be invisible. Under some circumstances like WOT and a dirty filter there may be some restriction but it's no different than a partially closed throttle. In a MAF car it shows less airflow. In a speed density car it shows up as more manifold vacuum.
There's the very small and I mean small chance that the car puts a lot of weight on the TPS position, much more common on speed density cars and you may have a slightly richer mix the first time you go WOT if you were to swap a clean filter for a dirty filter assuming it poses a restriction. However the 02 naturally takes care of this as the filter ages with short and long term fuel trims. For most cars, even if there was no 02 feedback it would not cause a rich condition.
