Took the k&n filter out after exhaust started showing signs of soot on the 2ltr NC. Filter had been in for 3k and wasnt cleaned or re oiled when i changed all the oils last mth (engine oil changed ever 6k). Have put back in a new standard filter, and now no more dirty tail pipes. Was worried if it had caused any other issues but car is running mint & got worried over reading stuff about MAF sensors (don’t know if NC has em). Looked on the K&N site as a number of reviews where saying this is only the case if the filter had been cleaned and then over oiled .(which i hadnt as filter had only done 3k).Any how’s the thing is now in the bin.
We are aware of the “urban myth” (K&N News Story) created by a few dealerships that a vehicle’s MAF sensor can be contaminated by K&N filter oil. No evidence has ever been provided to support this “myth” and years of diagnostic testing by K&N has shown that not only is this allegation not real, it is not even possible. In our opinion, it is an excuse for a dealership and/or the vehicle manufacturer to avoid a legitimate warranty repair. In the last 4 years, we have sold over 10,000,000 lifetime air filters and received only a few hundred calls from consumers who are having dealership or service provider challenges.
What do you do Richard - are you regularly dealing with MX5 owners in a way that would espose you to this experience?
Regrettably and I do mean this, as have used K & N before, there have been a number of threads on here highlighting this very issue and from my experience it is very real.
My experience is a little business that includes diagnosing faults and occasional sales of MAFs particularly for the MK2/MK2.5.
K&N are no different to other oiled cotton filters from Greenfilters, BMC et al (if they are materially different from other brands of oiled cotton filters, could these sourced differences be posted up).
I have seen several academic references referring to K&N filters now being factory fit parts by Abarth. The pricelist above is an official list of upgrade parts for the 500 Abarth from Abarth France. Note references to BMC airfilters (these are actually a no-cost delete option; BMC filters are factory approved by FCA. Fiat are not convinced that correctly used oiled cotton filters damage mass air sensors.
Roush, Saleen, Shelby and Dodge all use K&N filters on street upgrade packages for their respective products.
So some will say, based on experience and expert knowledge, that they will never use K&N filters (or, presumably, structurally similar filters). Professional engineers present their credentials, and their opinion deserves to be considered. Others express similar views, but have no relevant professional qualifications; those views should be discounted out of hand, as these are purely anecdotal.
Others will say, based on experience and expert knowledge, that they will happily use K&N filters (or, presumably, structurally similar filters). Professional engineers present their credentials, and their opinion deserves to be considered. Others express similar views, but have no relevant professional qualifications; those views should be discounted out of hand, as these are purely anecdotal.
K&N present test data, including SEM analysis. This is discounted as “they would say that anyway”, with the implication that K&N is engaged in criminally falsifying test data and misrepresenting their product. I have not seen any action by the ASA or others to challenge this data. Worse than that, K&N claims include statements that testing included independent laboratory analysis (K&N MAF Sensor Test Results), suggesting there is a criminal conspiracy to defend K&N products. Really?
K&N suggests if you have any dealership or mechanic try and claim that a K&N filter damaged their mass air sensor they will happily support the customer in pursuing action against that dealer/garage:
Mechanic blames K&N for a “failed” mass air sensor, and gets you to buy a replacement MAF through them. Send your old sensor off to K&N. They will test the sensor and report the findings back to you. If mechanics are confident in their diagnoses, this should vindicate them.
K&N states that the customer will not be out of pocket over a failed mass air sensor.
Saz9961, if you think I will disregard my own personal experience because you and a manufacturer of said product don’t think the problem that I discovered with a particular product exists apart from in my imagination, think again.
In my case (see my above post) I didn’t actually say that the MAF had been damaged. It did however suffer contamination resulting in a performance change. After three or four episodes of extra work to dismantle the air intake system and clean oil and dirt off the hot wire MAF on my car, I went back to a standard paper filter. The problem didn’t recur. The type of MAF on my car (not Mazda MX-5) was very delicate and very expensive to replace if damaged. Cleaning it was likely to damage it so I took the only sensible option.
I have no axe to grind against K&N. I am quite happy to fit oiled cotton air filters to two of my other vehicles because they don’t have hot wire MAF sensors. One is a motor bike with a carburettor and the other is a fuel injected car that doesn’t have a MAF sensor.
The issue is there is no clear answer, because of seemingly contradictory evidence (please, don’t present this as if its just me and the manufacturer, there are others in this thread to pick on with contradictory experience to you). Everytime the topic come up, its the same outcome, 50% will say no problem, 50% have a problem. No one is lying.
If the oil is transferring in some vehicles but not others, then one must look at how the filter was oiled in the first place. Everyone will say they did as per the leaflet.
The “real” issue might be the adequacy of the instructions provided by K&N to clean and oil the filter. Last time I used the oil, as I recall, it was just a regular aerosol nozzle; focused central, and misting outer. Users really just need to give the filter a misting. Some kits come with a squeeze bottle of oil.
To reconcile why some owners have a problem and some don’t, you need to examine the variables. In this case, the variable is how the filter is oiled.
Washing filter; there is a cleaner, which will emulsify any existing oil. This needs to be washed with low pressure running water. Some might just dunk into a bottle; that won’t remove the cleaner. Some might use a high pressure hose; that risks damaging the filter.
Drying the filter; in the UK you really need to let the filter dry at least overnight. You can’t apply oil to a wet filter and expect it to adhere.
Applying the oil; here the manufacturer could improve the product. Many users will end up with a filter overoiled in spots, particularly at the end oil the arcs. They is used to indicate that you’ve covered the filter, but people use it as if it were a paint. Getting an even coating while the oil is still sitting there on the surface. You need to let it wick before examining for adequate coverage.
Wicking; users need to let the oil wick. Here’s K&N’s instructions are incorrect. They recommend addressing uneven coverage while you are applying the oil.This is wrong. Let it sit, then examine the filter. As long as there are no white spots after wicking, you are good to go.
Cleaning frequency; K&N will state 100k for a panel filter, 40k for a cone filter. But fixed intervals don’t make sense for all cars operating under a variety of conditions. GM is now fitting pressure sensors to fleet vehicles to provide an indicator when a filter should be changed.
K&N oiling video. Ironically, in the demo video, K&N overoils the filter…
Dodge, Fiat, Saleen and Roush all use oiled cotton filters on their performance models. What is not clear is if they are sourcing the filters from BMC and K&N pre-oiled, (I think all the brands are supplied pre-oiled) and then treat them as a disposable part, or if they train their techs to service the filter. A K&N panel filter should be good for 100k miles between services (though obviously that is dependent on the workload of the filter). It is possible that, for the warranty period, the filter is never touched.
Seems standard, though I am intrigued about the comment about loose battery terminals damaging the mass air sensor. People who wrench their car themselves, probably disconnect the battery more frequently than the rest. I’m lazy, in that I loosen the clamps, then wriggle off the clamps off the post, wearing the soft lead post, until eventually the clamp is no longer really holding. Had this on a CRX in 'Bama. Hot humid conditions resulting in a slightly loose earth giving rise to a battery flattening. Redneck fix was some tin foil.
For those professionals, who are carrying out diagnostics of mass air sensors, it would be appreciated if they share their protocols for non-OBD cars. For OBD-2, I am assuming they are using factory-compliant diagnostic instrumentation.
Paul - did you try and take this up with K&N at any stage?
I imagine the process of complaint is a difficult one to engage in and will lead to further denial of a problem.
There was a contentious thread on the subject of K&N and the MX5 hot wire MAF a year or so ago but unfortunately I have not been able to find it. A pity to have to start from scratch with this when as I remember it was fairly well debated at the time.
…and yes this is not just K&N but as the premium manufacturer of oiled filters the issue is more relevant to K&N.
“If the oil is transferring in some vehicles but not others, then one must look at how the filter was oiled in the first place. Everyone will say they did as per the leaflet.”
The air filter that caused the problems on my car (it was a K&N, as it happens) came pre-oiled, new in the box, as they all do. Any problem with over oiling was caused by the manufacturer and no-one else. It soon became obvious to me that the problem with the vehicle I had occurred for two reasons:
The MAF was situated immediately after the filter.
It was of the fine resistance wire type, two wire filaments at 90 degrees to each other stretched across the entire diameter of the intake tube. It’s an extremely delicate component and the car manufacturer strongly emphasised the dangers of trying to clean it. I managed it using a cotton bud and carburettor cleaner and was surprised how much oil and dirt was on it each time, after a very short mileage.
“Paul - did you try and take this up with K&N at any stage? I imagine the process of complaint is a difficult one to engage in and will lead to further denial of a problem.”
Rhino, No I didn’t bother. I took the practical way out and replaced the oiled air filter with the original paper type. The manufacturer is hardly likely to admit a possible issue with their core business. It’s well worth bearing in mind that oiled cotton air filters pre-date fuel injection i.e. were for carburettors.
As I’ve said a number of times before, I’ve found the oiled cotton type of filter suitable for some vehicles, possibly not others. In the past (I’ve been modifying cars and bikes since the 1970s) I’ve used them on engines with SU, Weber and other carburettors without problems. I fitted an oiled cotton filter to one of my motorcycles just last year - but obviously these older engines didn’t have MAF sensors and cannot suffer from the problem.
The comment about over-oiling reminded me of the filters fitted to cars in the dusty tropics back in the 1950s, these were a labyrinth oil-bath type about the size of a pressure cooker where the incoming air literally passed though the sludge, usually initially old engine oil, and people wondered why the car was so lacking in power, but were happy to point at the tar-sands in the filter and comment on what a good job it was doing.
On one occasion I forgot to put in more oil after servicing (about every 2k-5k miles depending on time of year) the filter on my Dad’s Isis, and it went like a rocket compared with normal. Of course he noticed and added the oil.
My first Mk2 Zephyr six also had a big pot air filter, and I just cleaned it all out and put in a paper filter instead, it went much better. Later with the branched exhaust (Derrington? fifty years ago now) instead of the single pipe clamped along the head it went very much better still.
Just so you can't say that my views should be dismissed, or as you like to say 'not relevant'. I left school and went to the local tech for three years; I left with City & Guilds 383, Repair and Servicing of Road Vehicles Level 3, as well as a National Craft Certificate in Vehicle Mechanics & Systems. For nearly 30 years I've been involved in the repair, servicing or manufacture of motor vehicles in either a professional or domestic role.
With that out of the way, the OP posted about a panel filter worry. Whatever anyone says, be it a manufacturer or whoever else has an opinion, there is a risk of damage to a MAF by an oiled filter. It is common sense. If you put an oily rag over a vacuum cleaner nozzle some oil deposits will get sucked off. An engine will work in the same way, sucking in air through the filter.
One model of car I used to work upon many years ago used an oiled filter, when you took it out the housing there was an oily film over some of the inside where it had sat. That was with careful preparation of the filter. Luckily this model used a carburettor and had no sensors upstream to damage.
One thing that has been missed is that if you go the other way and don't oil them enough dirt and dust can get past the filter causing wear on the engine.
What I said was there is a risk and it's up to the individual as to whether they're happy to accept it.
There is enough information about the subject from both sides of the fence for an individual to make their own minds up.
Going back to the point I made at the beginning of this post, I like to take into account peoples findings, whatever qualifications they have. Practical hands on experience matters as much as letters after someones name or bits of paper. Anyone can sit behind a computer, do a Google search and spurt their findings.
Just like you did a couple of years ago about Toyo TiR tyres. For some reason you thought you knew more than someone who's profession is tyres.
'Others express similar views, but have no relevant professional qualifications; those views should be discounted out of hand, as these are purely anecdotal.'