Some manufacturers (BMW for one) are now talking 60k intervals for air filter changes, which to me seems grossly excessive if the engine is to run at maximum efficiency.
I personally feel that 20k intervals would ensure the engine is running close to it`s designed optimum and wondered what policy B.R`s adopt.????
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I run my cars under "bangernomics" principles so my opinions may differ to others on here.
I do all my own work on my cars and regulaly have my head under the bonnet, if I see the air filter looking dirty and dusty then I'll change it, as it'll only cost me £6 from the factors. Even so I still would'nt leave one on for 60k.
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Mine get changed every other oil change, so 12k miles. By then they're pretty black. I hate to think what it would look like after 60k!
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RichardW
Is it illogical? It must be Citroen....
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I never changed the one on my A2 because I couldn't find it!
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My Mercedes says 3 years or 36K. I do it at 18 months. or less, especially as I drive in London. Think about 10k a year at 26 mpg = 1746 litres, times 81p = £1414 per year. A .5% improvement = £7. Well worth a change I think apart from other benefits such as a good starting and smooth running.
The key to running older cars, and probably all cars that you wish to keep, is to over-service them.
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It all depends on the type of conditions in which you drive - out in the country is much different from being in a dirty, dusty town or city.
Oh for the days of cleaning the metal air filter, drying it and applying a thin layer of oil....
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Just done the ones on my Triumph.
Soak 'em in petrol and then a quick spray with WD-40.
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They are pretty cheap, so I go for the 20,000 mile interval, ie once per year.
My tractor, and LandRovers I had, have a large black canister with an oil bath in a detachable tray. Once in a while I tip the black oil away and refill it.
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I've still got the original on my 406 2.1td which has now done just over 60K and is now 7 years old. I take it out every year to see how dirty it is and give it a good bash to knock excess dust etc off it. But every year it's gone back in, and the car runs perfectly. It still does 38 to 46mpg depending on how and where it's driven.
"I hate to think what it would look like after 60K!" So I have one on my car for you to see "Richard W" if you wish!
I am probably going to get slated for it, but honestly it looks suprisingly clean an as I recall there is no, or virtually no oil staining on it. I was going to replace it a couple of years ago, but never got around to it.
Reggie
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Yeah, 60k does seem a long time for an air filter when we're used to 20-30k. But then again, 20k for an oil and filter seems to be an accepted interval when we were once used to 6k or 6 months. So aren't we just developing air filters in the same way?
Personally, I just follow the manufacturers recommendations of 20k or two years. Must admit, I have never changed it on a mileage basis cos I never do 20k in 2 years, so its always changed every other year instead. This means that the filter still looks perfectly clean, but is renewed anyway. But at less than £7.00 per filter (even for a genuine VAG part), it hardly seems worth it, to stretch it any further.
The old one had about 7000 miles on it, and it looked as clean as it was when it was put in.
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With modern ECU and monitoring of the combustion process surely the closed loop is making adjustments to ensure that optimum mixture is provided at all times. Clogging of the air filter to a limited extent is then acceptable. This is very different from the old days with a carb where a clogged filter effectively richens the mixture thro its choking effect.
Or am I missing something????
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pmh (was peter)
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Any clogging of air filter is not acceptable.It isnt a closed loop system.Closed loop is where oil fumes/burnt are drawn back into combustion chamber through inlet manifold.to be burned off.Same as sealed fuel system.ECU states when purging of vapour usually when engine hot/at high revs.then vapour is dumped
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Steve
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It's absolute stupidity imo if you live anywhere near trees. I clean out airfilters in November after all the leaves have fallen from the surrounding trees and the wind has blown them into our garage:-)
I always find at least one leaf in the air filter.. After 60k miles, I would imagine I could releaf a forest..
Not to mention pieces of straw dropped from trailers, and the odd sweet wrapper.. (we are close to a school and on a country road used by tractors),
Birch tree seeds are bad in spring - catkins everywhere :-(
And when I do the job again in spring: more rubbish...
Ok if you live in Singapore where the streets are much cleaner and the anti litter laws are enforced...
madf
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Steve.o
Sorry but you are wrong on this occasion, (however this terminology may have been used erroneously in older systems in the automotive industry).
'Closed loop' refers to a a control system which is adaptive, ie uses the Lambda sensor to monitor and adapts fuel supply to optimise combustion.
If in doubt do a Google on - closed loop lamba - you will find many examples including
www.adaptronic.com.au/comp.html which gives a comprehensive description.
madf
This will probably not overcome an airbox which is full of leaves, but should compensate for some restriction to flow.
I suspect Aprilia will have a definitive answer.
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pmh (was peter)
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>>>>>With modern ECU and monitoring of the combustion process surely the closed loop is making adjustments to ensure that optimum mixture is provided at all times. Clogging of the air filter to a limited extent is then acceptable. This is very different from the old days with a carb where a clogged filter effectively richens the mixture thro its choking effect.>>>>>
pmh - you highlight a valuable point re the ECU monitoring air flow through the engine and compensating the fuel charge accordingly, but the scenario we are discussing is where the air flow is severely restricted and way below its optimum.
If under these conditions the fuel flow is increased to compensate then surely fuel consumption will be adversely affected. Conversely if fuel flow is reduced to balance the reduced air flow, then engine performance will be reduced.
IMHO ECU engine management systems can only work to their maximum output if all the parameters are close to the manufacturers design tolerances, which can never be possible if air filters are not changed long before 60k miles.
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pmh..I will agree to disagree.I havent had time to check right through address you posted.But point I noticed.Not for street cars.Irellevent then to street car drivers.Wont comment further untill I have read it all..I cant see it applies on this thread?
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Steve
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An air filter is a relatively inexpensive piece of kit, that serves quite an important purpose. Furthermore replacement isn't usually difficult (and can be done with ease on most cars) there really shouldn't be any excuse as to why it isn't changed with more regularity. I personally will tend to change it yearly - whether it's on SWMBOs 330 or my own PUG 205 GTi.
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An air filter is a relatively inexpensive piece of kit>>
£20 for my VW Bora air filter and that's at a motor factor...:-(
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On my own car (Rover petrol turbo) I stick to the manufacturers spec'd 12k (24K for non turbo version).
I recently serviced a Vx Combo van for a neighbour. It had done 58k. The air filter was not the original as it was a aftermarket type. The change interval is spec'd as 24k. So this filter had probably done 34k. It was TOTALLY BLACK ON BOTH SIDES. The owner is non-mechanical and reported back that it ran like I'd fitted a new engine (granted I changed the oil too).
For £6 a pop I'm convinced they should be changed every 12k. Alternatively fit a K+N (replacement, not 57i) and wash every 12k
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I thought I read somewhere in the back room that K & N type oiled filters had a tendancy to foul the air mass sensors and were bad news. I suppose the extended change intervals could be due to an increase in the effective size of the filter. I must say that for a few quid it seems silly not to change it more often.
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If I think about it, I take mine* out about once a year, give it a brushing and, if it's handy, vacuum it as well.
*Air filter
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The point about closed-loop control of air-fuel ratio (mentioned above) is quite correct. The ECU will keep the air-fuel ratio at 14.7:1 (by mass) and therefore modest clogging of the air filter will not affect the mpg of the vehicle. It *will* however gradually reduce the power because you are restricting the airflow. This is why aftermarket 'induction systems' with freeflow air filters can give 5-10bhp power increase.
Obviously the point may come where the filter is so clogged that the car runs noticably badly because it can't pull enough air through at high rpm - but the filter would be black by that time.
Do not use oiled filters with hot wire/film MAFs - the oil vapour knocks the hot element out of calibration (as many Nissan 200SX, Mazda MX5 etc etc drivers can attest!).
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Aprilia, thank you for your support!
Do we know whether BMW have introduced a new technology to the air filters with extended service life or is it just based on empirical data with existing paper filters?
Can any BMW owners/maintainers indicate if the filters are any bigger (ie increased effective surface area) than used by other manufacturers for similar sized engines?
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pmh (was peter)
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Since when has a larger area of filter been of benefit.Most seem to clog up on within air intake/ie front side of filter.The other being to intake manifold side.Leaving middle section almost new.More they get clogged up more loss of power.Higher fuel consumption..I wont say you are wrong far be it from me to do so..But would be interested how this is going to be sorted. ie extended air filter life?
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Steve
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Larger filter area = less resistance to flow of air. Hence the potential for longer service intervals. This would however need to be combined with an air box design that ensures air inlet side could distribute air across the surface area of the filter without too much obstruction to flow.
To paraphrase posts, more clogging does not necessarily mean higher fuel consumption ( as was the case with old style non-closed loop systems which would start to run rich) provided you stay within design parameters. However less power resulting from obstruction to flow will ultimately reduce power, hence more right foot, and increased fuel consumption. Everything is a design compromise!
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pmh (was peter)
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