View Poll Results: Change or Not
Voters: 31. You may not vote on this poll
Are my cabin and engine filters dirty enough to change (ODO @ 15204 )?
Learn to read, boss- section 3.3 of the article you're using to prove me wrong. Fuel economy with a severely clogged air filter went down ~8% on FTP cycle testing, or ~16% on HFET testing. I'd consider that a reduction in fuel economy. As I said, this was a severe case, but again, that's what I've been saying all along. Thanks for playing, and good night 
Mark W.
Mark W.
Member
Joined: Aug 2009
Posts: 3,661
From: Georgia
Learn to read, boss- section 3.3 of the article you're using to prove me wrong. Fuel economy with a severely clogged air filter went down ~8% on FTP cycle testing, or ~16% on HFET testing. I'd consider that a reduction in fuel economy. As I said, this was a severe case, but again, that's what I've been saying all along. Thanks for playing, and good night Mark W.
Mark W.On fuel injected cars (i.e. Fits) the difference when the filter is clogged (not merely dirty) is insignificant.
Here, let me help:
Originally Posted by Oak Ridge National Labs
3.3.1 1972 Pontiac Grandville
While the filter restriction tested was severe enough to exceed 7.5 kPa at WOT, it is conceivable that some consumers never experience WOT and could allow their filters to become even more severely clogged (page 19).
The filter restriction in the Severely Clogged Air Filter Test 3 configuration (black column, Fig.3.17) was so severe that the driver had to consciously drive the vehicle in a manner that would not increase the throttle fast enough to cause a rich misfire condition during the HFET cycle. Once rich misfire was encountered, the vehicle was not able to maintain speed, and therefore, the test was invalid (page 20).
For Severely Clogged Air Filter Test 1, the HFET fuel economy decreased another 2.7% from the initial clogged air filter test (a 5.2% decrease from the new filter case). The progression from the initial clogged filter test and the Severely Clogged Filter Test 1 were on the same day, so no FTP data are available.
For Severely Clogged Air Filter Test 2, the restriction level was increased further to obtain a greater Outlet DP resulting in an additional loss of fuel economy. Fuel economy under the FTP decreased more than 5% from the initial clogged air filter test results and about 7.5% from the results for the new air filter. The HFET data for Severely Clogged Air Filter Test 2 showed a fuel economy decrease of about 3% from that in Filter Test 1 and more than 8% from that of the new air filter (page 22)
3.3.2 2007 Buick Lucerne
After observing the effect of continuously increased restrictions on the fuel economy of the 1972 Pontiac, the authors decided that a greater level of restriction should also be investigated on one of the newer vehicles. Thus the 2007 Buick Lucerne was retested to explore the effects of a more severely clogged air filter on its fuel economy (page 23).
The Lucerne was only tested over the double HFET cycle for these severely clogged filter simulation tests. The effects of the simulated severely clogged filter on the Lucerne’s fuel economy were not significant—less than 2%. These values are within the range for the series of tests that were conducted during the initial testing (page 23)
While the filter restriction tested was severe enough to exceed 7.5 kPa at WOT, it is conceivable that some consumers never experience WOT and could allow their filters to become even more severely clogged (page 19).
The filter restriction in the Severely Clogged Air Filter Test 3 configuration (black column, Fig.3.17) was so severe that the driver had to consciously drive the vehicle in a manner that would not increase the throttle fast enough to cause a rich misfire condition during the HFET cycle. Once rich misfire was encountered, the vehicle was not able to maintain speed, and therefore, the test was invalid (page 20).
For Severely Clogged Air Filter Test 1, the HFET fuel economy decreased another 2.7% from the initial clogged air filter test (a 5.2% decrease from the new filter case). The progression from the initial clogged filter test and the Severely Clogged Filter Test 1 were on the same day, so no FTP data are available.
For Severely Clogged Air Filter Test 2, the restriction level was increased further to obtain a greater Outlet DP resulting in an additional loss of fuel economy. Fuel economy under the FTP decreased more than 5% from the initial clogged air filter test results and about 7.5% from the results for the new air filter. The HFET data for Severely Clogged Air Filter Test 2 showed a fuel economy decrease of about 3% from that in Filter Test 1 and more than 8% from that of the new air filter (page 22)
3.3.2 2007 Buick Lucerne
After observing the effect of continuously increased restrictions on the fuel economy of the 1972 Pontiac, the authors decided that a greater level of restriction should also be investigated on one of the newer vehicles. Thus the 2007 Buick Lucerne was retested to explore the effects of a more severely clogged air filter on its fuel economy (page 23).
The Lucerne was only tested over the double HFET cycle for these severely clogged filter simulation tests. The effects of the simulated severely clogged filter on the Lucerne’s fuel economy were not significant—less than 2%. These values are within the range for the series of tests that were conducted during the initial testing (page 23)
Member
Joined: May 2011
Posts: 293
From: On the road...
I think that the OP's air filter is still fine (yeah, a little dirty on the surface but nothing terrible) but the cabin filter is shot. I believe the manual does state to replace the cabin filter more often than what the MM recommends if you drive in industrial areas/cities...
Please never breed. My point: in extreme cases, a clogged air filter can impact fuel economy. Section 3.3 of your article says just that. How is that not clear enough? Ask mommy to draw you a picture. Stop pasting webspace and tossing this thread- Mark W.
Member
Joined: Aug 2009
Posts: 3,661
From: Georgia
Now for a refresher:
A dirty filter absolutely WILL reduce fuel economy. If the engine is struggling to pull in sufficient air, it will increase load, and therefore, fuel consumption. Granted, they have to be much dirtier than the OP's before that will become an issue, but the point stands. However, to add to your point:
A *somewhat* dirty engine air filter (such as the OP's) will not reduce fuel economy Mark W.
A *somewhat* dirty engine air filter (such as the OP's) will not reduce fuel economy
Mark W.no, it won't. Read the link. Modern fuel injection meters fuel according to air flow for the correct ratio.
Even carbureted cars do, but not as perfectly, through analog venturi action. Less air-flow resulted in less fuel delivered through the ports. Prior reports to the 2009 study vastly overstated the benefits of changing air filters on these cars.
Engines don't "struggle" to pull in air. Air is allowed to enter unless restricted by a throttle. At idle it's almost fully restricted. All a dirty air filter does is add to the restriction. The only impact is to top end (WOT) power when the throttle is fully open, but some restriction is still provided by the air filter (and whatever else is in front of the throttle).
It amazes me how professed gear-heads can be so wrong on a simple mechanical aspect.
Even carbureted cars do, but not as perfectly, through analog venturi action. Less air-flow resulted in less fuel delivered through the ports. Prior reports to the 2009 study vastly overstated the benefits of changing air filters on these cars.
Engines don't "struggle" to pull in air. Air is allowed to enter unless restricted by a throttle. At idle it's almost fully restricted. All a dirty air filter does is add to the restriction. The only impact is to top end (WOT) power when the throttle is fully open, but some restriction is still provided by the air filter (and whatever else is in front of the throttle).
It amazes me how professed gear-heads can be so wrong on a simple mechanical aspect.
Member
Joined: May 2010
Posts: 3,417
From: Capital Distric New York
A year and a half and a decrease in air flow to the cabin is what told me when to replace the HEPA cabin filter. 30Kmiles told me when to replace the air filter. They both occurred at the same time.
Member
Joined: Dec 2008
Posts: 76
From: Sacramento, CA
You can change the filters as often as you like, as long as you have the money. The engine filter looks white on the inside of the filter, I recently changed mine at 25K just because. The cabin filter, I like to change every 10K, you have to breathe that stuff in.
I chunked my cabin filter and replaced it with oiled K&N pre filter foam.. between the dust and pollen around here I would go broke replacing filters. A dirty cabin filter will prevent good airflow and cause your A/C to freeze up on hot humid days and we have a lot of them here... It is surprising how cold your car will get without a cabin filter .... My wife noticed an improvement in fuel mileage and throttle response when the air filter on her Forester was changed at 13000 miles.. I always put extra oil on my K&N type Spectra filter when the weather is very dry and dusty... I spray it and let it dry and repeat the process after driving it a few days or even a few months... With the dry conditions and wild fires that came within 300 yds of my property in September I could feel a bit of grit in my engine oil so I can tell that I need to oil the filter more often between cleaning it or get a foam sock to cover it when conditions are as extreme as they were this summer... I think that anytime you are in doubt, change it out.... I apply that theory to most all of the expendable items that require replacement as part of the maintenance required to keep things working well.
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