I realise that in dusty or dirty conditions you may need to replace them more often. But here in town in UK, typically how often ? Every couple of years, three years ?
I ask because my car is now out of warranty and at its last annual service in a glass palace main dealer the service bill showed, and I paid for, a new air filter. I didn't take a look and check that it was actually done. Now the warranty has ended and so yesterday I had it serviced at my trusted independent place who told me it needed a new air filter.
I trust my independent place and have never trusted the dealer having caught them out a couple of times in the past.
Thoughts please.
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What does the servicing schedule say? If it's a paper type one they are generally cheap enough, just change it yourself. No more than a couple of minutes work generally, what car is it that you have?
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When I took my Subaru to a pain dealer for a fool service, they just blew the dust out of the air filter and refitted it.
As sooty says, take the critter out and have a look at it - can you see light through it if you hold it up to the currant bun.
A blocked or even partially-blocked air filter will increase fuel consumption.
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>>A blocked or even partially-blocked air filter will increase fuel consumption.
But would it on a fuel injected engine? You'd certainly lose performance, but wouldn't the MAF signal air flow to the ECU and fuelling would be adjusted to suit?
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>> But would it on a fuel injected engine? You'd certainly lose performance, but wouldn't the
>> MAF signal air flow to the ECU and fuelling would be adjusted to suit?
Yes, because you lose performance your right foot compensates with more throttle.
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>>
>> >> But would it on a fuel injected engine? You'd certainly lose performance, but wouldn't
>> the
>> >> MAF signal air flow to the ECU and fuelling would be adjusted to suit?
>>
>> Yes, because you lose performance your right foot compensates with more throttle.
>>
Most car air filters have a substantial surface area so the flow is little restricted even at the point that a change is due. I.e. if the engine can still draw enough air to deliver the normal levels of performance and efficiency then no extra fuel should be used. If it is really clogged then right foot compensation may be necessary.
I have been thinking of changing the M135i's air filter between services, they cost so little in the scheme of things and take minutes to change, and it's not a bad idea to dyson out the air box now and then.
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>> fuel should be used. If it is really clogged then right foot compensation may be
>> necessary.
>>
If the filter is so clogged that sufficient air cannot be drawn in, then in a modern fuel injected electronically controlled engine, how is right foot compensation going to work?
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>> If the filter is so clogged that sufficient air cannot be drawn in, then in
>> a modern fuel injected electronically controlled engine, how is right foot compensation going to work?
>>
You would probably get an engine fault light and limp mode.
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>> >> If the filter is so clogged that sufficient air cannot be drawn in, then
>> in
>> >> a modern fuel injected electronically controlled engine, how is right foot compensation going to
>> work?
>> >>
>>
>> You would probably get an engine fault light and limp mode.
>>
Yes, my thoughts exactly.
I believe the electronics will see mass air flow, not pedal position.
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>> I believe the electronics will see mass air flow, not pedal position.
Both, but fuel is matched to airflow predominantly.
The missing part is the throttle opening, which is the principal bottleneck for air being sucked into the engine.
The point is that the air cleaner isn't blocked, it's just slightly more obstructive. For the same throttle position less air will pass, less fuel will be added, less power produced.
That can be compensated for by a wider throttle opening to achieve the same airflow as could be achieved with a smaller throttle opening and a less blocked filter.
Near full throttle, there will be a point beyond which insufficient compensation is available, and at full throttle there will be none and you will just have to settle for less power.
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Mega snip quote!
>> Near full throttle, there will be a point beyond which insufficient compensation is available, and
>> at full throttle there will be none and you will just have to settle for
>> less power.
Totally!
Last edited by: VxFan on Thu 25 May 17 at 21:50
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>> Erm: >>
St Just because it's online don't mean its true Dog.
Anyway the conclusion re gasoline engines is that the modern ones suffer a performance drop when clogged though not economy, though as Zero says if you make up for the performance loss with you right foot (rather than simple pootle about slower) you will use more fool ..
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Ahem . . it was under warranty, I didn't want to mess with getting it serviced outside the main dealer network (I know I can but it will lead to too much hassle in the event of a claim). I didn't see a need to check if the dealer had replaced the filter - would you ? My indie, who I trust, fitted a new one because in his view it was needed, so no need to check.
The question remains - is an air filter once a year a reasonable thing or was I ripped off by the main steale r.
PS This is for interest and info only, I'm not going back there again.
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I usually change them every other year: 20-30k in the case of our cars. They're usually pretty dirty by then. It's such a PITA on a PSA 1.6 HDi in C4 Picasso / 307 (as it's tucked under the scuttle over the back of the engine) it's not worth doing more often!
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I think on both our cars (Berlingo and Skoda Roomster) it's a 'major' service item so probably biennial/20-25k. Last service for the Roomie included a 'service filter pack' without itemising which from oil/air/fuel/cabin were included.
On some previous cars minor service included remove and vac air filter to clean out leaves, insect corpses etc.
My Pug 205D of beloved memory had a foam one you could remove and wash.
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My car is a change at alternate services, 25,000 miles.
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Thank you all. It seems every couple of years is the view, which was mine too. The trouble is, if you check that all main dealer service items have been done you're half-way to doing it yourself.
My previous issue with this dealer was about locking wheel nuts. At a service they wanted to change the front disc pads - the mileage was around the right figure for me so I agreed. I got a call to say the locking wheel nut is damaged and they couldn't remove the wheels. They pointed out that the front tyres had been changed since their last service and the damage was 'clearly' the tyre fitters' fault. It just so happens I know my tyre fitters well and it wasn't them. I examined the distorted splines of the lock nut under a magnifying glass and the direction of distortion was evidence of bending when the nut was undoing not tightening up. I met the service manager, with my magnifying glass, and told him if he didn't accept my view (as a chartered engineer) I would get a metalurgist's report and see him in court. He backed down and fitted the pads for free using a newly ordered locking nut.
Main Dealer 0 Customer 1
Last edited by: Dulwich Estate II on Thu 25 May 17 at 13:10
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>> was evidence of bending when the nut was undoing not tightening up.
So previously overtightened, I guess?
Neither the dealer nor the tyre fitter would see my car again.
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>> So previously overtightened, I guess?
Or locking 'key' used incorrectly?
I should add though that I'm a 'newbie' to alloys having successfully ducked them until last two vehicle purchases where they were standard.
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They dealer might not have fitted the key properly when they removed them.
Although i binned all of mine, too much faff with them. Much higher risk than them getting nicked.
Last edited by: sooty123 on Thu 25 May 17 at 14:52
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>> Although i binned all of mine, too much faff with them. Much higher risk than
>> them getting nicked.
I worked that one out with a puncture and a broken one at 8pm one winter's night in Cambridge.
Never used them since.
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>> Although i binned all of mine, too much faff with them. Much higher risk than
>> them getting nicked.
>>
I agree, if anyone is going to remove my wheels I swap the lock nuts for the original standard ones and refit the locks when I get the car home.
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> The question remains - is an air filter once a year a reasonable thing or
>> was I ripped off by the main s******.
I change mine once a year but it's cheap, about 6 quid, and about two minutes to change. The oh's Toyota is a 4yr/60k item its an almost wool material and about 20 odd quid.
What does the service schedule say DEII?
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'What does the service schedule say DEII?'
Every 20,000 miles or second year. The main dealer invoice does not itemise the cost.
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It surely depends purely on mileage? (apart from air dustiness, obviously)
If the filter really self-blocks just from sitting unused then you have to wonder what's been happening while it was on the dealer's shelf.
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>> 'What does the service schedule say DEII?'
>>
>> Every 20,000 miles or second year. The main dealer invoice does not itemise the cost.
I would stick with that then.
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>> The question remains - is an air filter once a year a reasonable thing or
>> was I ripped off by the main steale r.
>>
You woz robbed.
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"You woz robbed."
Yes Sireee! By the same outfit that screwed up my locking wheel nut.
Naming and shaming is pointless - if you look at their reviews, all totally genuine I'm sure, they get about 4.5 stars out of 5.
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>> >> Erm: >>
>>
>> St Just because it's online don't mean its true Dog.
>>
Conversely, it doesn't make it untrue. Especially when backed by Oak Ridge National Laboratory
>> Anyway the conclusion re gasoline engines is that the modern ones suffer a performance drop
>> when clogged though not economy, though as Zero says if you make up for the
>> performance loss with you right foot (rather than simple pootle about slower) you will use
>> more fool ..
>>
That doesn't make sense to me at all.
Last edited by: BrianByPass on Thu 25 May 17 at 17:10
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>> >>
>>
>> That doesn't make sense to me at all.
>>
>>
It does to me. If there is a constriction in the intake then you will have to rev it harder in a lower gear in order to suck more juice in.
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From jalopnik.com
"when a driver pushes his or her gas pedal, an accelerator pedal position sensor (APP) sends a signal to the ECU, which then commands the throttle to open. The ECU takes information from the throttle position sensor (TPP) and APP until the throttle has reached the desired position set by the driver. But what happens next?
Either a mass air flow sensor (MAF) or a Manifold Absolute Pressor Sensor (MAP) determines how much air is entering the throttle body and sends the information to the ECU. The ECU uses the information to decide how much fuel to inject into the cylinders to keep the mixture stoichiometric.
The computer continually uses the TPS to check the throttle’s position and the MAF or MAP sensor to check how much air is flowing through the intake in order to adjust the pulse sent to the injectors, ensuring that the appropriate amount of fuel gets injected into the incoming air.
In addition, the ECU uses the o2 sensors to figure out how much oxygen is in the exhaust. The oxygen content in the exhaust provides an indication of how well the fuel is burning. Between the MAF sensors and the 02 sensor, the computer fine-tunes the pulse that it sends to the injectors."
The car's electronics do not care nor know whether the MAF or MAP are measuring air coming through a new-clean or old-clogged air filter.
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Presumably a difference between how much air the ECU thinks it should be getting according to throttle position and what it is being told it is actually getting by the MAF sensors would cause it to flag an error?
That aside, wouldn't a clogged air filter just be much the same as a throttle open slightly less far? Presumably therefore more less power rather than directly more fuel consumption?
In fact if you continued, were it possible, to maintain the same throttle positions as with an unflogged filter, you'd actually use less fuel? As surely the equivalent of a lesser throttle opening would be similar to more economic driving?
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>> The car's electronics do not care nor know whether the MAF or MAP are measuring
>> air coming through a new-clean or old-clogged air filter.
And you do not know anything other quoting stuff written in web articles*. For example, how about enrichment to prevent pinking on large throttle openings? how about temp of air being drawn in? (larger air flow usually mean colder air)
At the end of the day, its all about volume, more volume more power. An air filter less than efficient will cause the engine to be less efficient.
Perhaps you could tell us why manufacturers specify replacement periods for filters?
*do you spend your day quoting wiki passages or bits from newspapers at everyone? Is there any independent or original thinking or understanding going on in Bypass world?
Last edited by: Zero on Thu 25 May 17 at 20:52
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>>
>> The car's electronics do not care nor know whether the MAF or MAP are measuring
>> air coming through a new-clean or old-clogged air filter.
>>
>>
But it doesn't know what gear you are in?
It seems obvious to me - if your car is running less well or is struggling for whatever reason
(blocked air filter, seized wheel bearing, baler twine wrapped round the drive shaft, dodgy fuel, potato stuffed in the exhaust, or steep hill) then you drop a gear and increase revs by flooring the accelerator.
That uses more fuel.
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>>
>> That doesn't make sense to me at all.
>>
See Manatee's post above, it make perfect sense ( because he's not talking about politics ;-) )
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I changed the air and pollen filters on my VW's petrol engine about six months ago.
The pollen filter did need changing but, to my surprise, the old air filter was virtually as clean as the previous time I'd replaced it about nine months earlier.
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Air Filter Replacement - how often ? - sooty123
