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skins

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skins Grand Master

skins

Posted
Posted

So Clean Air Filters Don’t Help Fuel Mileage?

While cruising the wide world of web recently, I landed on a .gov website with an interesting article that I thought had some interesting results. The premise of the article is that the US Department of Energy wanted to know how vehicle maintenance effected fuel mileage, specifically dirty air filters. So they did an experiment with 4 cars:

  • 2003 Toyota Camry 2.4L
  • 2007 Buick Lucerne 3.8L
  • 2006 Dodge Charger 5.7L
  • 1972 Pontiac Grandville 455ci (aww yea)

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blk94r33 Mentor

blk94r33

Posted
Posted

It may not have improved fuel economy, but everything else was hampered...

How were they comparing fuel economy, constant speed on a dyno? Engine power would be down across the board, and the drivers would compensate on a normal road by applying more throttle to reach their desired usual acceleration...

A clogged air filter might not directly influence fuel economy under these conditions, but who's vehicle will be in tip-top near new shape, with just a clogged air filter? Take into account a vehicle that doesn't get it's regular maintenance, worn spark plugs, out 1 degree timing, blocked fuel filter, 5psi down in one tyre, brake caliper with sticky slides, then watch the numbers drop...

I'll stick to changing my air filter regularly... thumbsup.gif

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mad082 Grand Master

mad082

Posted
Posted

there is 2 major reasons why a dirty air filter that is restircting airflow won't really affect fuel economy (at low load or constant speed).

1: the oxygen sensor

2: if a filter is restricting airflow then the AFM will be registering less airflow and therefor injecting less fuel, however you may see higher load values from the TPS to accomodate the extra throttle required to get the same speed or acceleration. in theory this would add in more fuel, but the oxygen sensor then over rules this. the best way to look at it is that the engine requires a certain amount of air to maintain a fixed speed. as long as the load value is low enough to keep it in closed loop mode then you will always use pretty much the same amount of fuel.

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