Sweet, this is why I installed a gauge on my air box. It has 12k on it or so and it has not even ratcheted up one notch.
Dirty Air Filter= Almost No Effect on Fuel Economy
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What are you using for a gauge?
Originally Posted By: Onmo'Eegusee
Sweet, this is why I installed a gauge on my air box. It has 12k on it or so and it has not even ratcheted up one notch.
You mean since we had that discussion... not all that long ago... you've cranked on 12K. Gad Zukes, man! You should stop driving long enough to at least take a shower and have an occasional conjugal visit.
BTW, was that a sarcastic "sweet," as in "Sweet, I just went to a lot of unnecessary trouble." Or, " Sweet, I just learned something?"
Sweet, this is why I installed a gauge on my air box. It has 12k on it or so and it has not even ratcheted up one notch.
You mean since we had that discussion... not all that long ago... you've cranked on 12K. Gad Zukes, man! You should stop driving long enough to at least take a shower and have an occasional conjugal visit.
BTW, was that a sarcastic "sweet," as in "Sweet, I just went to a lot of unnecessary trouble." Or, " Sweet, I just learned something?"
I'm not gonna "check" my filter any more than necessary to determine how long I'm comfortable running it. The more times you disturb the AF the greater the chance of injesting dirt. Apprx 20k works for me. I never remove the AF unless I have a new replacement on hand. I don't "knock out" dirt 'cause you may loosen the dirt up and injest more dirt if you reuse a dirty filter.
Originally Posted By: Jim Allen
Originally Posted By: Onmo'Eegusee
Sweet, this is why I installed a gauge on my air box. It has 12k on it or so and it has not even ratcheted up one notch.
You mean since we had that discussion... not all that long ago... you've cranked on 12K. Gad Zukes, man! You should stop driving long enough to at least take a shower and have an occasional conjugal visit.
BTW, was that a sarcastic "sweet," as in "Sweet, I just went to a lot of unnecessary trouble." Or, " Sweet, I just learned something?"
Nonono, the filter has 12k since it was last replaced. I think it had a new one in it when I bought it, since it was whiter than me at the time.. My actual mileage is somewhere around 11k a year. At this rate, I wont have to put another filter in this particular air box. I plan on installing the Marauder Air box and MAF after I do the exhaust..
"I just learned something." I pretty much suspected what they documented here was true already, knowing how vehicle computer control systems work, but its nice to have a paper.
This is what I am using.
Originally Posted By: Onmo'Eegusee
Sweet, this is why I installed a gauge on my air box. It has 12k on it or so and it has not even ratcheted up one notch.
You mean since we had that discussion... not all that long ago... you've cranked on 12K. Gad Zukes, man! You should stop driving long enough to at least take a shower and have an occasional conjugal visit.
BTW, was that a sarcastic "sweet," as in "Sweet, I just went to a lot of unnecessary trouble." Or, " Sweet, I just learned something?"
Nonono, the filter has 12k since it was last replaced. I think it had a new one in it when I bought it, since it was whiter than me at the time.. My actual mileage is somewhere around 11k a year. At this rate, I wont have to put another filter in this particular air box. I plan on installing the Marauder Air box and MAF after I do the exhaust..
"I just learned something." I pretty much suspected what they documented here was true already, knowing how vehicle computer control systems work, but its nice to have a paper.
This is what I am using.
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That looks pretty similar to what's on the new chevy trucks.
I havent seen any on chevys with the new body style. Maybe I was not paying attention.
It is closer to what ford puts on the PSD air intake, but I purchased mine new..
It is closer to what ford puts on the PSD air intake, but I purchased mine new..
Interesting study. Despite the fuel economy not being impacted, I did notice the following statement...
"Acceleration performance on all vehicles was improved with a clean air filter."
So, it would seem that having a dirty air filter does have some impact the vehicle's performance.
"Acceleration performance on all vehicles was improved with a clean air filter."
So, it would seem that having a dirty air filter does have some impact the vehicle's performance.
Originally Posted By: sjlee
Interesting study. Despite the fuel economy not being impacted, I did notice the following statement...
"Acceleration performance on all vehicles was improved with a clean air filter."
So, it would seem that having a dirty air filter does have some impact the vehicle's performance.
At low throttle and RPM, a clogged air filter isn't really a restriction.
Once you open the taps, not only is there lower peak flow, but there is also a big discrepancy between throttle position and air flow. AFAIK, the ECU will read that as higher load, and tend to richen the mixture or retard the ignition timing a bit to be safe. Hence, lower performance.
Interesting study. Despite the fuel economy not being impacted, I did notice the following statement...
"Acceleration performance on all vehicles was improved with a clean air filter."
So, it would seem that having a dirty air filter does have some impact the vehicle's performance.
At low throttle and RPM, a clogged air filter isn't really a restriction.
Once you open the taps, not only is there lower peak flow, but there is also a big discrepancy between throttle position and air flow. AFAIK, the ECU will read that as higher load, and tend to richen the mixture or retard the ignition timing a bit to be safe. Hence, lower performance.
Originally Posted By: d00df00d
Originally Posted By: sjlee
Interesting study. Despite the fuel economy not being impacted, I did notice the following statement...
"Acceleration performance on all vehicles was improved with a clean air filter."
So, it would seem that having a dirty air filter does have some impact the vehicle's performance.
At low throttle and RPM, a clogged air filter isn't really a restriction.
Once you open the taps, not only is there lower peak flow, but there is also a big discrepancy between throttle position and air flow. AFAIK, the ECU will read that as higher load, and tend to richen the mixture or retard the ignition timing a bit to be safe. Hence, lower performance.
Throttle position has little to do in the equation.
On a mass air car, it reads less air with a dirty filter. No compensation required.
On a speed density car it sees more intake manifold vacuum for a given throttle position with a dirty filter. Little to no compensation needed.
The only thing you lose is power.
To the OP, thanks for the link. I've been preaching this for years, especially on the Acura board and they think I'm crazy.
Originally Posted By: sjlee
Interesting study. Despite the fuel economy not being impacted, I did notice the following statement...
"Acceleration performance on all vehicles was improved with a clean air filter."
So, it would seem that having a dirty air filter does have some impact the vehicle's performance.
At low throttle and RPM, a clogged air filter isn't really a restriction.
Once you open the taps, not only is there lower peak flow, but there is also a big discrepancy between throttle position and air flow. AFAIK, the ECU will read that as higher load, and tend to richen the mixture or retard the ignition timing a bit to be safe. Hence, lower performance.
Throttle position has little to do in the equation.
On a mass air car, it reads less air with a dirty filter. No compensation required.
On a speed density car it sees more intake manifold vacuum for a given throttle position with a dirty filter. Little to no compensation needed.
The only thing you lose is power.
To the OP, thanks for the link. I've been preaching this for years, especially on the Acura board and they think I'm crazy.
To let the computer know what % reactor power you are requesting, of course.
When my air filter is clogged(usually at the 12 month interval), I need to rev the engine more, shift later, downshift earlier.... and end up with worse fuel economy.
New airfilter and suddenly engine feels free and MPG increases.
I'm looking for reasonable MPG and HP. If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
New airfilter and suddenly engine feels free and MPG increases.
I'm looking for reasonable MPG and HP. If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
Originally Posted By: unDummy
If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
Not much, if the OP's link is accurate. Your ECU looks at available airflow, mixes a reasonable amount of fuel to maintain decent combustion, and thumbs its nose at the guy mashing down on the accelerator.
If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
Not much, if the OP's link is accurate. Your ECU looks at available airflow, mixes a reasonable amount of fuel to maintain decent combustion, and thumbs its nose at the guy mashing down on the accelerator.
The only change point would be when you hit about 70% throttle, it goes into enrichment mode and ignores the O2, and goes to hardcoded fuel table, although its still metering air. In another EPA article on higher ethanol, some cars appeared to apply the O2 fuel trim correction to the WOT fuel table. Another way of fixing this is wide band O2s which some makers are starting to use.
Originally Posted By: unDummy
When my air filter is clogged(usually at the 12 month interval), I need to rev the engine more, shift later, downshift earlier.... and end up with worse fuel economy.
New airfilter and suddenly engine feels free and MPG increases.
I'm looking for reasonable MPG and HP. If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
Good point. Bear in mind, they did show a MPGdrop in their simulations. It just wasn't the huge drop "common knowledge" would have us believe. No doubt there are exceptions to this as well... they didn't test every possible combination or type of EFI system. This test just allowed me to relax a little and eke a few more miles out of the filter and save a coupla bucks. A somewhat dirty air filter isn't going to cost any MPG in a "normal" driving environment if it only cost a percent or two when plugged so badly that the car can barely drive.
When my air filter is clogged(usually at the 12 month interval), I need to rev the engine more, shift later, downshift earlier.... and end up with worse fuel economy.
New airfilter and suddenly engine feels free and MPG increases.
I'm looking for reasonable MPG and HP. If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
Good point. Bear in mind, they did show a MPGdrop in their simulations. It just wasn't the huge drop "common knowledge" would have us believe. No doubt there are exceptions to this as well... they didn't test every possible combination or type of EFI system. This test just allowed me to relax a little and eke a few more miles out of the filter and save a coupla bucks. A somewhat dirty air filter isn't going to cost any MPG in a "normal" driving environment if it only cost a percent or two when plugged so badly that the car can barely drive.
Originally Posted By: unDummy
When my air filter is clogged(usually at the 12 month interval), I need to rev the engine more, shift later, downshift earlier.... and end up with worse fuel economy.
New airfilter and suddenly engine feels free and MPG increases.
I'm looking for reasonable MPG and HP. If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
The point that nearly everyone misses is that dipping deeper into the throttle to compensate for a dirty air filter does not mean worse mpg. Airflow is airflow no matter how open or shut the throttlebody is. If it takes 1/2 throttle to get 300CFM with a clean filter and 3/4 throttle to get the same 300CFM with a dirty filter, nothing changes.
Now if you have an automatic and the car shifts later due to the larger throttle opening, that would be the only way you're getting worse mileage.
When my air filter is clogged(usually at the 12 month interval), I need to rev the engine more, shift later, downshift earlier.... and end up with worse fuel economy.
New airfilter and suddenly engine feels free and MPG increases.
I'm looking for reasonable MPG and HP. If I don't have the HP that I need, I step down on the gas further and for a longer amount of time. What happens to MPG then?
The point that nearly everyone misses is that dipping deeper into the throttle to compensate for a dirty air filter does not mean worse mpg. Airflow is airflow no matter how open or shut the throttlebody is. If it takes 1/2 throttle to get 300CFM with a clean filter and 3/4 throttle to get the same 300CFM with a dirty filter, nothing changes.
Now if you have an automatic and the car shifts later due to the larger throttle opening, that would be the only way you're getting worse mileage.
Originally Posted By: Onmo'Eegusee
The only change point would be when you hit about 70% throttle, it goes into enrichment mode and ignores the O2, and goes to hardcoded fuel table, although its still metering air. In another EPA article on higher ethanol, some cars appeared to apply the O2 fuel trim correction to the WOT fuel table. Another way of fixing this is wide band O2s which some makers are starting to use.
Many newer cars such as my TL use a wideband and stay in feedback even at WOT.
Older cars like my GN still base WOT fueling on long term fuel trims. So unless the filter goes from new to plugged in less than a minute, it's still compensated for. In fact, in my early tuning days I had to get a fuel trim lockout programmed into my chip because everytime I would adjust fuel pressure to alter WOT fueling it would compensate nearly immediately with no changes to fueling.
The only change point would be when you hit about 70% throttle, it goes into enrichment mode and ignores the O2, and goes to hardcoded fuel table, although its still metering air. In another EPA article on higher ethanol, some cars appeared to apply the O2 fuel trim correction to the WOT fuel table. Another way of fixing this is wide band O2s which some makers are starting to use.
Many newer cars such as my TL use a wideband and stay in feedback even at WOT.
Older cars like my GN still base WOT fueling on long term fuel trims. So unless the filter goes from new to plugged in less than a minute, it's still compensated for. In fact, in my early tuning days I had to get a fuel trim lockout programmed into my chip because everytime I would adjust fuel pressure to alter WOT fueling it would compensate nearly immediately with no changes to fueling.
Excellent post! I've been wondering about this for a long time now as well.
I've always thought that any pumping losses induced by a dirty filter could be "cancelled out" by the wider-opened throttle plate. More restriction in one area, less in the other? Or would I be splitting hairs?
I've always thought that any pumping losses induced by a dirty filter could be "cancelled out" by the wider-opened throttle plate. More restriction in one area, less in the other? Or would I be splitting hairs?
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