K & N

[Drivbiwire]

This is simple enough for anyone. Go down to your local parts store take a brand new K&N filter out of the box (get a panel filter) rip the plastic off and hold it up so that you are looking through the filter at the lights above your head. See the small holes that are letting light shine through......
Guess what else goes through? IF you dont believe it.......LOOK

on a side note... the dirt that goes through all those little holes. Acts like a sand blaster to your turbo vanes spining at 100K + RPM. We have a local shop that collects the turbines out of powerstrokes with K&N filters in them.

501 miles with a K&N and an OEM filter element behind it to stop the crap from getting in...

DB

 

[whitedog]

501 miles with a K&N and an OEM filter element behind it to stop the crap from getting in...

DB

That is a picture that is in the link that dh linked elsewhere. Note that this isn't from a VW and the filter in the picture is actually a Fram filter. It's in this link.

 

[verdeo]

WB9K,

Welcome to the TDI club! I have been passing the time tonight reading this thread. DBW, DD, and many others here are really good souls. I've been a member for several years now, and I've read enough posts to learn to listen to these good people. Yes, I used to use K&N filters on my gassers, and I must admit that the only improvement I have had, if one wants to call it that, is noise. I've realized that the process of maintaining one of these filters is a PITA, and ever since I joined this forum I've stuck with OEM paper filters. I've even stopped changing my oil every 3,000 miles, although I was a nervous wreck for months with my first TDI.

YOu seem concerned why more of us don't jump into the ring here, or offer more test results. I for one, don't see this subject worth the effort again and again. Maybe I've changed a good deal since my conversion from high revving gassers, but I find peace of mind and convenience much more important these days.
I am a transplanted Michigander...not far from Detroit, with a father that was chief mettallurgist at (of all places, Buick) so I do have some understanding of where you are coming from. If you really want to settle into a new environment (TDI) you must take a deep breath, maybe have a bit of wine, and understand the beginning of this thread was perhaps DBW's attempt to preach to the choir, or to remind us why we have made many choices on Fred's TDI. I don't always agree with everything said on this forum...but Geez, DBW speaks, and I certainly will listen!
Now, if we are talking the best tire, summer and winter...or shocks, or whatever, I will definitely have some pretty serious opinions...yet I can read information on this forum and respect most of the opinions without getting my nose all bent out of shape. I guess what I'm saying is...there is a great deal of incredible information gathered here with many incredibly intelligent people participating. You have a choice of trying to stir up conversation for the common good...and you can also put some barbs into it. Please sit back, read items through the search engine...but honestly, this thread is turning into a pi$$ing contest, to my eye.

Can we all get along?
Gary

 

[40X40]

Duane,

Welcome to the club. Gary said what I was about to. Listen to the veterans here, Diesels and gassers are quite a different breed, and big diesels and our little ones also have little in common.
I went from 100 HP to 150 HP with only a chip and did not need to upgrade my air filter. Others here have performed dyno runs and founds such little gains on our cars regarding K&Ns that the gains could be passed off as
"noise". (about 1 HP, if I recall correctly.) We expect our cars to last 300,000 miles or so (without overhaul!) and clean air is critical.

Bill

 

[Dale Seiler]

I looked at the pictures posted of the ugly filter housing and did notice a lot of dust around the edge of the box which I would think is because the dirt went around the filter and not through it. If the filter fits properly then you will see a clean line on both the upper and lower flange around the edge of the box. It did not fit properly or the filter box was left open or is warped.
You post pictures of a car that you know nothing about when it comes to maintenance history and did say all the other maintenance items also needed attention. It would seem to me that the car was neglected from the get go don't you think. You don't know when this filter was installed, by whom or how it "was not" maintained as per the manufacture spec.
If someone chose to use a K&N filters then the proper fit and maintenance is very important. Many people buy them but don't maintain them worth a dam. I have seen bad K&N filters from time to time and the failure can be tracked to poor maintenance or no maintenance. Some of you guys come across the bad filter and then cry wolf.
I have run the K&N filters in my motorcycles, cars and trucks for many years without the problems you mention. No dirt in the air intake tube on either my gas vehicles or turbo diesels. I have had no problems with the MAF sensors either. I use the factory cleaning kits and follow the direction to the letter The filters have given me great service and I continue to use them.
K&N does say in small print that the filter should be replace if the cotton mat is open or disturbed and should be replaced after repeated cleaning.
I did not chime in to support or defend the K&N product just to say some people have great success with them. Paper filters are good too.
PS
You may want to re-think the MAF in the injection process it is not the PRIMARY as you put it. The engine will run without one. It will not run without TRS/SRS or TPS sensors. Those are big diesel terms but I am sure you can translate them to kraut.

Go Rockies

 

[Dale Seiler]

And there in lies your lack of understanding of how a turbo diesel engine operates or for that matter functions.

You do realize tha the MAF sensor is the PRIMARY source of control for fuel injected to the motor? You do realize that more air in the cylinder WILL NOT RESULT IN MORE POWER FOR A DIESEL ENGINE since ALL DIESEL ENGINES ALREADY HAVE EXCESS AIR DUE TO THEM BEING LEAN BURN COMBUSTION ENGINES...At idle they run as lean as 100:1 and at full load they are at 35:1 and NEVER approach 14.7:1 like gassers???

Are you reading that book up side down again?
Or you just been haging around them NASCAR boys.

Motor uses electricity to convert (electromotive force) into mechanical force. It does not covert the form of the energy supplied. Heater motor, wiper motor, trolling motor. Diesel or gasoline motor, never seen one. One exception is motorcycle it does have a engine. Should be engine-cycle don't you think.

Engine uses gasoline or diesel fuel that is converted to hot expanding gases through combustion. Hot combustion gas is converted to mechanical energy. Bang, pistons go up and down, crank goes round and round.

I like it when you use all caps, show me your heart rate is up. Do you sit there and scream as you type?

I need that book you are reading, you know the one that says the MAF sensor is the primary for injection in the engine, sorry motor. Not at any school that I went to or the books I teach out of. The TPS, ECM, EDU and TRS/SRS are the main sensor for fuel injection. If the MAF was the primary then why do they smoke when you push down on the go peddle. If the MAF is in control of injection then I had better get my butt back into the big three, CAT, Cumins and Detroit schools. I'll bet you a dollar to a donut that VW uses the same sensor areas with about the same priority levels.

You are wrong about the amount of air in the engine not effecting the power out put of the engine. Long before the turbo charger was introduce as a standard production component, we called the engines naturally aspirated. Intake valve opens and the downward stroke of the piston pulls in one cylinder full of air plus a little exhaust that was not blown out by the lack of a turbo. Called (valve overlap) designed to open both intake and exhaust valve at the same time to scavenge exhaust gasses from the cylinder.
Turbo charged diesel engines can pack up to 30 times more air (30 PSI) or more into the cylinder (under load) then can naturally aspirated engines. Horse power and torque rise without adding fuel because of the greater air charge raises cylinder pressures and burns the fuel more completely. The valve over lap then lets the turbo charger push the combustion exhaust from the cylinder because both valves are open at the same time.

Where did you get the idea that the engine has excessive air and there for is lean burn. What does that mean? You been reading sales brochures again?
If I add 30 time the normal atmospheres to the cylinder then inject fuel the full travel of the piston then they produce soot. Soot is unburned fuel and is all over the tail pipe area on my trucks and the little TDI. If they are clean burn then you need to tell California EPA they have made a serious mistake, by not letting the west coast boys by a new TDI.

At idle they run as lean as 100:1, 35:1, 14.7:1 means what? compression ratio! are you comparing natural aspiration to turbo charged air or just compression ratio in general? Lean means not enough fuel for the air mixture. Cylinders run hot and exhaust valves burn. Rich means too much fuel for the amount of combustion air. cylinders produce soot and if fuel reaches the piston in a liquid state it will burn a hole right through it.

You really crack me up sometimes.

 

[bhtooefr]

Uh, those aren't compression ratios, those are air/fuel ratios.

And, he got that idea from reality.

Stoichiometric for a diesel is roughly 14.6:1, actually. Look it up. So, yes, diesels run VERY lean normally.

 

[40X40]

A diesel mechanic and diesel instructor that doesn't know TDIs run lean? When I take my foot off the throttle and the fuel shuts off is that what you call rich?
Yeah Right...

Some new-body is an impostor.

Lurk for a few months, then post.

Bill

 

[l1o9s7t6]

we are discussing DIESEL ENGINES

Lean means not enough fuel for the air mixture. Cylinders run hot and exhaust valves burn. Rich means too much fuel for the amount of combustion air.

Only a GAS engine runs hot when lean.

No fuel= no heat

 

[Drivbiwire]

Are you reading that book up side down again?
Or you just been haging around them NASCAR boys.

Motor uses electricity to convert (electromotive force) into mechanical force. It does not covert the form of the energy supplied. Heater motor, wiper motor, trolling motor. Diesel or gasoline motor, never seen one. One exception is motorcycle it does have a engine. Should be engine-cycle don't you think.

Engine uses gasoline or diesel fuel that is converted to hot expanding gases through combustion. Hot combustion gas is converted to mechanical energy. Bang, pistons go up and down, crank goes round and round.

I like it when you use all caps, show me your heart rate is up. Do you sit there and scream as you type?

Just a way for me to emphasize when you need to shut-up and pay attention for once...

I need that book you are reading, you know the one that says the MAF sensor is the primary for injection in the engine, sorry motor.

Better yet straight from THE book itself...Then again I am probably reaching assuming you know how to read a 3D map.

Not at any school that I went to or the books I teach out of. The TPS, ECM, EDU and TRS/SRS are the main sensor for fuel injection. If the MAF was the primary then why do they smoke when you push down on the go peddle.

Does a TDI smoke so much that it fails to meet emissions standards for Tier II bin10? come to think of it any motor in stock form DOES NOT smoke, it may emit a slight haze under full load but thats it. Modified, well you get what you get.

If the MAF is in control of injection then I had better get my butt back into the big three, CAT, Cumins and Detroit schools. I'll bet you a dollar to a donut that VW uses the same sensor areas with about the same priority levels.

Then again we are not talking about CAT or other motors that don't meet Tier II Bin 10/8/5 are we?

You are wrong about the amount of air in the engine not effecting the power out put of the engine.

OK genius, please do tell what the BTU content of air is?

Long before the turbo charger was introduce as a standard production component, we called the engines naturally aspirated. Intake valve opens and the downward stroke of the piston pulls in one cylinder full of air plus a little exhaust that was not blown out by the lack of a turbo.

Wrong again.... The turbo was there to increase the available air for combustion and to another extent create a further increase in the peak temperature of combustion due to higher pressures achieved during the last stage of compression in the cylinder. The higher pressures effectively increase the overall efficiency of the motor...Did you catch that I said efficiency not power.

Called (valve overlap) designed to open both intake and exhaust valve at the same time to scavenge exhaust gasses from the cylinder.

Your on crack! TDI's have NO VALVE OVERLAP, Even the naturally aspirated ones NEVER HAD VALVE OVERLAP! You can't have valve overlap in a diesel interference engine!

Turbo charged diesel engines can pack up to 30 times more air (30 PSI)

30psi is NOT 30 times the amount of air...You teach this stuff? LMAO!

or more into the cylinder (under load) then can naturally aspirated engines. Horse power and torque rise without adding fuel because of the greater air charge raises cylinder pressures and burns the fuel more completely.

In a "Perfect" world that does not subscribe to the laws of physics...maybe. I'd like to see your formula for this motor you describe.
More air with higher pressure at the start of compression does in fact increase efficiency...slightly. Engine makers once they build in a certain level of efficiecny they have the option of converting that efficiency into power or reserving it to meet emissions, it's called compromise.

The valve over lap then lets the turbo charger push the combustion exhaust from the cylinder because both valves are open at the same time.

If you mention "Vavle overlap" one more time around here...You will be laughed off this board!

Where did you get the idea that the engine has excessive air and there for is lean burn. What does that mean? You been reading sales brochures again?

Lucky for you no, Diesel engine cycle 101...Do you shave yet?

If I add 30 time the normal atmospheres to the cylinder then inject fuel the full travel of the piston then they produce soot.

What is the nozzle configuration?, vertical or angled? 5,6,7,8 holes? Piezo or analog actuation? CRI, VE or PD pressure source?
How about the bowl design, thickness of the bowl lip? Conical or dome? How about the squish area, raised compression ring?
And that is just the tip of the iceberg when it comes to what affects combustion, notice I never mentioned the amount of air in the cylinder? Reason being there is always excess air in the cylinder, the design of the piston and the bowl determine the way the fuel burns.

Soot is unburned fuel and is all over the tail pipe area on my trucks and the little TDI. If they are clean burn then you need to tell California EPA they have made a serious mistake, by not letting the west coast boys by a new TDI.

Just checked my neighbors Honda gasser, yup soot in the tailpipe...

At idle they run as lean as 100:1, 35:1, 14.7:1 means what? compression ratio! are you comparing natural aspiration to turbo charged air or just compression ratio in general? Lean means not enough fuel for the air mixture. Cylinders run hot and exhaust valves burn. Rich means too much fuel for the amount of combustion air. cylinders produce soot and if fuel reaches the piston in a liquid state it will burn a hole right through it.

You really crack me up sometimes.

Child, go back to grade school and I hope your parents take away your computer...

DB

 

[Drivbiwire]

The point about different MAF types is duly noted, though I kind of doubt that the film MAFs actually have semiconductors printed on them. Capacitors or wire resistors maybe, but semiconductors seem highly unlikely to me. (Ever seen a clean room? The filters are just the tip of the iceberg--those guys wear spacesuits. De-ionized air is forced from vents covering the entire ceiling through vents in the floor. The "floor" is really just a giant vent grate. WAY cleaner than any airbox, I don't care what filter you're running.)

Cheers!
dh

Straight from a TDI and viewed under an SEM (Scanning Electronic Microscope). This was a failed MAF after it was contaminated with oil and dirt.

The way the sensor works is there is a temperature reading taken at the front of the board, then as the air follows the surface area (laminar) it gets heated by the center heating strip. Then as the air traverses to the rear of the sensor another temperature reading is taken. Depending on the rise in temperature of the boudry of air passing over the sensor the volume of air flow into the motor can be determined.

The sensor is capable of more than 1000 samplings per second...

DB

 

[whitedog]

You can't have valve overlap in a diesel interference engine!

I gotta call BS on this. It just isn't true. It may be true on the TDIs, but it is not an all encompassing statement for EVERY diesel interference engine.

Please be more accurate in your statements, Pete. You are an expert with TDIs, no one doubts that, but you seem to think that all other diesel engines still run on 1960s technology.

 

[whitedog]

Straight from a TDI and viewed under an SEM (Scanning Electronic Microscope). This was a failed MAF after it was contaminated with oil and dirt.

The way the sensor works is there is a temperature reading taken at the front of the board, then as the air follows the surface area (laminar) it gets heated by the center heating strip. Then as the air traverses to the rear of the sensor another temperature reading is taken. Depending on the rise in temperature of the boudry of air passing over the sensor the volume of air flow into the motor can be determined.

The sensor is capable of more than 1000 samplings per second...

DB

I don't see what proves that this was caused by dirt. Can you show us, please?

 

[Drivbiwire]

With recessed valve pockets sure some. But with the TDI configuration, "vertical valves" you can't have it unless you greatly machine the valve recesses ruining the flows in the cylinder, which is why it's typically not done.

Also with stricter emissions due to NOx, scavenging is it not in the best interest of emissions, kind of like a pseudo EGR without the valve. Cat if I recall prefers this over the EGR valve.

DB

 

[Drivbiwire]

Dirt accumulates at the front of the sensor, the normally smooth boundry of air is disturbed causing the heated portion (center of the plate) to overheat due to the lack of laminar airflow accross the central portion of the circuit. The plate once overheated cannot detect airflow accurately and results in a gradual decline in detected airflow. Since the plate is NOT shorted out no code is triggered since the circuit is still functioning.

DB

 

[Drivbiwire]

Inlet side (dirty side), Note: I bent down two areas so that you can see between the pleats.

Dirt was uniform in coverage accross the whole filter surface area as it should be.

The "filtered side", not much in terms of leakage around the seal, in fact the seal appeared to have a very good fit and the dual edges appeared to be glossy as in having been in firm contact with the engine side of the airbox.

The tell tale was when you held the filter up to the light, you can see the thousands of holes accross the whole area of the filter where dirt was migrating thru.

DB

 

[ruking]

Actually for the pro "oiled air filter media" advocates, this might be a good long term a/b test!! I am sure all the vendors would be happy to increase their MAF sales!?

I was really amazed at the conclusion drawn by one of those "pro" advocates, with (mineral) oil coating all the affected areas that it was a slam dunk for him to conclude that (mineral) OIL had NOTHING to do with the deterioration of the MAF!!?? Now is that a blood hound that can't smell? Indeed the oil media own web site indicates that oil migration is NOT supposed to happen!!??

Also this is not even to mention the TDI is NOT designed to intake (ingest) mineral oil in combustion, or the increase in silicon allowed in.

I just recently bought 1 gal of (food grade) mineral oil @21.75 per gal. It would be interesting to calcuate what K&N sells their mineral oil (red formula) for? Do they sell it in 16 oz containers or less?

 

[WB9K]

Oh, come on.

Thanks to all who posted friendly welcomes. This thread has veered well off topic in spots and it is starting to smell kinda pissy and I apologize if I've crossed the line from legitimate questioning into whining and screaming. I try not to do that, but it's not always easy.

I've spent way too much time on this thread already, but I'm going to press on just a bit more here. I think it's obvious that the filter cited as an example at the beginning of this thread was not at all maintained for a very long time in a very harsh environment and was probaby never installed right to begin with. Look at the latest pictures. You can see where there was leakage at the seams of the airbox on all four sides of the dirty side, plain as day. On the "clean" side, there are also signs of leakage around the filter, especially at the lower right and upper left. It's right there in the photos. Because it's due (a little overdue, actually) I opened the airbox on my 96 Buick over lunch to see how my K&N was looking. It has been untouched since installation about 50,000 miles ago. Dirty side was pretty dirty, no screen on the box, so there are leaves and dead bugs in the mix, but most of that side still has it's red color. The clean side looks brand new and that side of the airbox is spotless. THere's a MAF there too, but I haven't pulled it to look at it. I'm hardly worried. (BTW DB, I haven't owned a car with points and condenser for 20 years.) I'll post photos this week if anyone asks for them before I clean the filter. Now, surely DB has changed enough air filters to know that there was a lot more amiss in his sample car than the filter type. But why let the facts get in the way when you've got an internet full of idiots who need to be protected from themselves, right?

Look at the link where the Fram "2nd filter" test came from. I posted a link to the whole test last week, I wonder how many actually looked at it. Notice that the Napa Gold paper filter is just barely cleaner than the K&N. Note also that the Napa Gold is just barely cleaner than the tightest paper filter the tester could find. Look at how the Amsoil filter makes the K&N look pristine. Rather than show us the test and let us see the whole context, we are instead shown a photo of the K&N results only and told "Look at all the crap these things pass!". Huh. That was a little misleading, wasn't it?

In the battery thread we were told (among other things) that CCA is a meaningless spec (it isn't) and that if we don't get a 72Ah battery minimum for our TDI, we would get stranded. After all, some cars these days draw 5000 Watts (=400Amps) as soon as you put the key in. When pressed for details, we find out that the megaAmp car is an ultra luxury model with a two-battery system. More than that, you would have to turn on all the lights full blast, all seat heaters full power, pop in a DVD for the RSE system and max that volume out, put in a special test CD with sine waves targeting the max passbands of each channel of the digital amplifier and crank it (better wear earplugs, that's gonna hurt) aaaaand...let's see, windshield wipers, mirror and window defoggers, plug some electric heaters into the cigarette lighters....maybe we should make a checklist to make sure we can get stranded as often as possible.Let it set like that for a while now because when you turn the key to start, those things are all going to turn off so the starter can do its thing. Make sure you drive around like that too--the alternator might be able to keep up if you don't. GMAB, no idiot could be clever enough to figure all that out, so why mention the "factoid" at all? To keep the idiots scared?

DB is a master of spin and distortion who (in my short experience here) gives out little to no actually useful information until he's so pissed off that HE'S YELLING AT YOU. Sorry, but "because I said so" doesn't cut it for me. If you can't handle the questions that come from thinking people when you use a red herring as a prime example of something, then don't post at all. You're propogating mythology and.....bull****.

If my making that observation makes me a troublemaker or worse, then so be it.

Pacem,
dh

 

[Flytofish]

All I know is that my brother is a long time hotrodder. He's built engines that shouldn't even be able to hold up to what he put them through, but they do. He's built motors for a local circle track racer, which allowed him to place in the tops in his class. I'm not saying he's a professional, because he doesn't get paid to do it, but out of anyone, and I mean anyone, I know, he's got more knowledge about engines.
he had a 1998 Chevrolet 2500 with a gas engine. It has a MAF sensor in it. My brother used to be a hardcore K&N user, and even convinced me that they were the best. This all changed when his truck started running like a pile of turds. He couldn't figure it out. Nor could five other shops over a period of 3 months. He eventually decided to throw parts at it to see what would happen. guess what, the MAF sensor was completely covered with oil residue and this caused it to fail. He swapped the sensor, and it ran like a champ! He switched the air filter for a factory one, and hasn't had any problems since.
Personally, I don't see how oil can help an air filter. I know that it helps attract the dirt particulates, but when it soaks up all it can, what happens then? I would think that most people don't pull them and clean them often enough, which can lead to problems. I'm not a professional air cleaner technician, but it stands to reason that if a liquid has trapped all that it can, then anything else that approaches it will pass through unrestricted. The cotton elements being used seem to be fairly thin and very porous. Open for debate.

 

[ymz]

I don't see how oil can help an air filter.

Hey... my first two VW's had oiled metal mesh air filters...

Millions of air-cooled VW owners can't be all wrong...

Yuri.

 

[alphaseinor]

... though I kind of doubt that the film MAFs actually have semiconductors printed on them. Capacitors or wire resistors maybe, but semiconductors seem highly unlikely to me.

Thin film process is a printed one, where it's definately a clean room. The current breakthroughs on the TF proceses are in the PV solar industries. check out nanosolar.

(Ever seen a clean room? The filters are just the tip of the iceberg--those guys wear spacesuits. De-ionized air is forced from vents covering the entire ceiling through vents in the floor. The "floor" is really just a giant vent grate. WAY cleaner than any airbox, I don't care what filter you're running.)

don't forget the sticky mats on the floor... staging areas... etc...

... Actually I used to work in an ion implant shop... no space suits, we had a nice Liquid Helium chamber in all of our machines to eliminate dust and debris. It creates a cold spot where everything in the chamber is drawn to it, it's a better vacuum than the space in our solar system.

 

[ruking]

Hey... my first two VW's had oiled metal mesh air filters...

Millions of air-cooled VW owners can't be all wrong...

Yuri.

Did those millions of air-cooled VW's have MAF's?

One data point, my 1970 VW Beetle did NOT!? I did use 30W oil in my oem oil filtration air filter!

 

[WB9K]

Thin film process is a printed one, where it's definately a clean room. The current breakthroughs on the TF proceses are in the PV solar industries. check out nanosolar.



don't forget the sticky mats on the floor... staging areas... etc...

... Actually I used to work in an ion implant shop... no space suits, we had a nice Liquid Helium chamber in all of our machines to eliminate dust and debris. It creates a cold spot where everything in the chamber is drawn to it, it's a better vacuum than the space in our solar system.

I never doubted that the conductors were printed onto the film--just that they were semiconductor material. I used to work in the engineering lab of a company that made custom industrial controls, many of them temperature controls. All of those thermocouples used probes consisting of dissimilar metals--usually alumel/chromel wire or iron/constantin wires. I suppose truly semiconductor thermal sensors may exist, but to use them in such a harsh environment as these seems like begging for trouble to me--they'd be much too exposed to expect anything like long-term integrity. I would bet the printed-on material of the sensors is metal--not doped silicon and the like. I could be wrong. Does anybody here know for sure the composition of the printed conductors on the MAF film? BTW (this is for DBW), the number of samples that can be taken from a sensor is a function of the computer doing the processing of raw data from the sensor--not the sensor itself. You could take a zillion samples a second from any sensor at all if your computer was fast enough.

Working in a clean room never sounded like much fun to me, but is probably interesting at least. I've heard of nanosolar. Some very exciting breakthroughs in printed solar technology lately.

dh

 

[DieselOx]

Diesel Ox,
Outstanding suggestion! I'll buy a paper filter and perform a test ASAP, probably this weekend. Live driving while watching the MAF readings should do it, yes? Engine block 3, I think. Any other suggestions?

I'd think you'd want to log (record) at least MAF requested, MAF actual, boost, and one of: road speed or throttle position or MAP? You can log up to 4 parameters, then take the numbers and graph them in excel.

From what I've learned, I'm betting you won't see any difference in boost (if you actually do get more air, the ECU will cut the boost accordingly to what it wants; that's what makes this whole debate moot, in my opinion). I could see MAF changing slightly from one to the other, but I don't know enough about how MAF is controlled, or the actual difference in air flow between the 2 filters (more suface area (stock) v. bigger holes (k and n)).

Have fun.

 

[ymz]

Did those millions of air-cooled VW's have MAF's?

Mine did... Metallurgically Anemic Floorboards... yup... anyone who lived in a cold climate where lots of salt was used on the roads can testify to that...

(Just trying to lower the temperature around here...)

Yuri.

 

[rdkern]

I've got a 67 that I might be getting rid of .... Want another air-cooled? It's got the oil air filter. Oil in that filter hasn't been changed in this administration (can't recall if it got changed during Clinton either).

 

[whitedog]

Dirt accumulates at the front of the sensor, the normally smooth boundry of air is disturbed causing the heated portion (center of the plate) to overheat due to the lack of laminar airflow accross the central portion of the circuit. The plate once overheated cannot detect airflow accurately and results in a gradual decline in detected airflow. Since the plate is NOT shorted out no code is triggered since the circuit is still functioning.

DB

Thank you. That was a clear explaination that makes sense rather than just showing a picture and saying "Believe me".

From this, I can draw a conclusion that if dirt isn't collecting on the leading edge of the sensor, there won't be a problem.

So what causes the dirt to accumulate there? Oil that is, black gold, Texas tea.

With a properly oiled filter, there shouldn't be any oil shedding off of it, therefore it shouldn't cause a problem.

Of course that oiled chiken wire passing as a filter is still passing lots of dirt to sand blast the turbo vanes and dust the engine, but a perfect oiled filter shouldn't cause the MAF to fail.

(Notice I left some wiggle room in there. It's a shyster Lawyer trick I learned from TV.)

 

[Drivbiwire]

A static charge also attracts dirt or fine dust to the sensors leading edge. This in part is why VW requires such a fine level of filtration...Of course the aluminum compressor appreciates this high level of clean air as well.

DB

 

[brucep]

I can think of ONE reason that some kinds of engines tend to get more power and throttle-response while using an oiled-guaze airfilter.

Those engines which use MAP (Manifold Absolute Pressure) intake may respond better when oiled-guaze is installed.
This is because this engine design CALCULATES the airflow into the engine based on pressure-differential.
Using a filter which has less pressure-drop across it than the original-design, fakes-out the engine-computer so it modifies the injection and timing paramators.
There may be a sense of more power. (and perhaps even some MPG improvment)

The more-accurate, MAF type of design which VW uses actually MEASURES the airflow into the engine so it is not possible to fake-out the engine-computer by changing the airfilter.

I also want to say that I do not buy-into the hype of the oiled-guaze filters. There is no question that they filter worse..... just the opposate of what an airfilter is supposed to do!!

 

[WB9K]

A few questions and an olive branch.

I do have a couple questions about the SEM photos if you don't mind, DB. (And if you do mind, that's OK too.) Your explanation of the MAF failure makes sense to me, I'm not questioning that at all. I assume that all of the photos are of the same unit? Am I correct in assuming that the bulk of the "stuff" along the heating strip is the heat-damaged membrane of the MAF itself? Was any materials analysis done on this? Do we know which temperature sensor is the leading one? Based on the contour of the damage and debris, I would guess the left hand one. Either way, what is that dark streak that runs lengthwise down it's middle? It's interesting that this area's length is located right about parallel to where the damage to the central heating strip occured. I'm not sure what that would suggest, maybe just a byproduct of a turbulence pattern?

While I'm asking you these things, I should say that I think it's obvious that you have a lot to offer in the way of knowledge and experience here. I just wish you would present things in a way that let the facts speak for themselves rather than allowing apparent biases to dictate how the facts are presented (or not presented). I hope I can say that without getting anyone's feathers ruffled. I look forward to reading your thoughts on the above questions.

Pacem,
dh