K&N and air flow sensor
 

Gilly, I thought I'd start a new post rather than hijack Luxury Addict's.

Ok, so what I've read from other posts here, the K&N contaminates the air flow sensor with oil and this somehow damages it? I've never heard of that before, how does it damage it? I'm guessing the oil coats and insulates the sensor and prevents it from reading temp correctly? I would think a blast of brake cleaner would take care of that? Shoot, let me know because I have one on my car and I was just about to buy one for another.

Thanks!

It will contaminate the MAF if you oil the wrong side or over oil the filter. Many people like to blame a product for their own stupidity. Besides that, Mercedes MAF's are known to be pretty much crap and will fail around 40,000 to 50,000 miles regardless. I have been a K&N user for over 10 years and have had no issues in any of my cars. At the very least, it is nice to keep the old filters out of the landfills.

Lots of people have had problems. My experience that that the MAF is touchy, and you must be carefule about over oiling the filter. In my opinion, there is a very fine line between over and under oiling the filter.

I get a bit paranoid about under oiling, used to race cycles, and saw what gets through if under oiled.

OTOH (on the other hand) I almost always get a seat of the pants increase putting in a K&N.

Why not try it and see if the performance gain is worth it? Start on the dry side, i.e. put the oil on evenly and sparingly.

IMHO, having a new SL, I don't want the dealer refusing to pay for a failed MAF when they see the K&N.

Greg

I always oil 'em up real good myself. I bought one for the 99CLK in April, but it looked dry around the edges like buttered toast at a truck stop diner. I sprayed it to bring it up to my standards, but now I'm a little worried.
I did a net search on cleaning the MAF in other cars, but after removing the difficult security screws holding it in, it isn’t at all what I expected. There looks to be a exposed zener diode on it, and a flat strip of exposed metal. Anyone know what the story is there??
The MAF, intake tube, plastic grid and screen are all oil and dust free so I’m just going to leave the K&N in there for now. Judging from its looks I would think you could soak it in oil.

Being a guy from the old school, I'll just post some thoughts. I've seen some of these KN filters with no requirement of oil saturation. They are supposed to boost air intake. How do they do that you may ask. There is another thread that follows a spectographic analysis of oil with a KN filter and shows high contamination. It could be that the extra air comes from a reduced micron rating of the air filter. I know KN filters come from racing where the engines are TORN DOWN AFTER 500 MILES. I suppose you could do that. Oiling the filter is what you do to lawn mowers. Is you car a lawn mower? Soeone here has used KN filters for 10 years, but how much driving does he do, and what is the real condition of his engines. Car mfgs have designed air filters to keep ring and cylinder wall wearing grit out of the engine. I think they know what they are doing. Do you think they would miss an opportunity to increase power if they could just change the air filter design? I'm sticking with a good quality stock air filter and get another 300,000 miles on my car. If your rings get ground to nothing by partially filtered air, how are you going to prove that it was that racing style air filter that caused the excessive blowby and oil consumption. Meanwhile the after market mfgs are banking your money while you try to figure out how to pay for an engine. That's just my take as a 30 year professional MB mechanic.

Peter

OK, so you want to put keep the old air filters out of the landfill and put mass airflow sensors in there instead?
Once they are contaminated, they're junk.
Unless I see some test results from an independent testing lab, I'm not buying the performance claims either, but for something without a hot-film mass airflow sensor, I don't see a problem with using them.
I've never heard anyone claim the K&N's only create problems if they are "oiled on the wrong side", could be though, but never considered that.

Gilly

My MAF went out on my E55 before I installed a K&N. Pretty much all Mercedes MAF's fail in short order regardless of a K&N.

http://www.knfilters.com/facts.htm#RESULTS

http://home.earthlink.net/~jeweldr/tech/air1.htm

Ooohh, controversial topic, I love it! I respect everyone’s opinion and I certainly appreciate everyone’s input!

Gilly:
Yes, maf sensors take up less space in land fills so I'm doing my part. Seriously, my chevota will choke on a paper filter so I know there is performance difference. My Benz motor is less than ½ the size, but so is the surface area of its filter. I didn’t “feel” a difference when I put it in, but I doubt I would notice if there was. I don’t disregard what you’re saying, but I think since I can’t feel any oil in the intake that I’m probably ok? Then again I don’t how much they can take before they’re damaged.
So that strip of metal is the “hot-film” maf you referred to? I was expecting a coiled filament when I opened it up. I delicately wiped its surface with a Q-tip and there was zero evidence of oil or anything, no streaking etc viewed with a 10X eye loupe. If it does go it wouldn’t be the first auto part I’ve broke in my pursuit of performance, I’ve got a box of expensive broken dreams on a shelf to toss it into.
Do you or anyone know how the oil damages it? Come to think of it, I wonder why they don’t just measure intake manifold pressure (or vacuum depending on how you look at it).

Autozen:
I agree a good paper element filters well, maybe better, but certainly disagree about car mfgs. I believe they use paper because it’s cheap and it works. If the mfg is willing to change the design or shape of a part to make more power, then cars would have headers, pre-oilers, use synthetic oils, transmission coolers, etc etc. But in their defense I can see them shying away from K&N because the element is easily damaged, and if you don’t wash and oil correctly you’re in trouble. So they’re certainly not for the general public.

SEC and Greg:
I oiled both sides, and well. Certainly not dripping, but probably double what was on there out of the box. A dry K&N is a useless K&N.

I thought the hot film looked like a chunk of black plastic.....been awhile since I looked at one. What the oil does to it is "contaminates" it, that's how I heard it described. And it's pretty delicate, it surprises me that you say you "decontaminated" one. I heard once they bite, they're junk, I guess I said that already though. Even a leaking air intake is said to damage them, just little pits from being hit by dirt particles, very sensitive to "anything".
The old injection systems used a "hot wire" sensor, and these were more durable, but not as good, I guess.
They used to use a intake manifold pressure sensor, and couple that with a barometric pressure sensor and sort of get info they wanted, but mass air flow is pretty much the industry standard right now, I thing intake manifold pressure, for a natural aspirated engine, is pretty passe right now...

Gilly

I've yet to see any proven dyno numbers on naturally aspirated Mercedes engines with K&N's. I've only seen slight losses, especially with the older engines without MAS's to even worry about. Can someone post a genuine dyno test that proves K&N improve horsepower on a naturally aspirated Mercedes engine?

Gilly:
No, I have not decontaminated one. I just read about it and am willing to try it if I need to. I don’t know why the MAF won over the MAP, I’m sure there’s a good reason, I just hope it’s not profit in the replacement parts dept. Yes, it looked like a chunk of plastic, but there was the strip semi-hidden within it. The zener diode is 100% exposed and at first glance it appeared that was all there was to it. I thought wtf, maybe it’s a magic zener, but then I saw the metal strip. I still have no clue why the zener is exposed like that.

EuroCoupe:
I hear ya. I think most stock cars could care less, but also factor in that most of a paper filters life is not spent fresh and clean. The K&N really shines when it’s dirty, meanwhile a dirty paper element is choking the motor out. I see a lot of dust where I live, especially in my chevota because it see off-road action. If I put a new paper filter on it I will feel a significant loss in power, but no loss in my K&N covered with filth and ½ the pleats literally filled with dirt. In fact, I gets so dirty so quick that I use a pre-filter most of the time. You need to be careful with those too, only one type can flow enough to match the K&N, and you guessed it; a K&N brand pre-filter. 

Some engines just like being stock, any changes and it will hurt performance. Example; some lose power with a freer flowing muffler. Is it the mufflers fault? No, the problem most likely lies in the fuel delivery and ign timing. All engines will make more power if they can breathe better, but they need to manage that extra air to do it.

I think what looks like a diode is the temp sensor for the engine management.

Gilly

Chevota

To answer your question (" why MAF over MAP "), .......simple.
MAP only measures load & airflow, MAF measures the volume of air & temperature of the incoming air.
Cold air being denser than hot air, is therefore calculated into the fuel requirements of the engine, to maintain an optimum air/fuel ratio.
Been running K&N on just about every piece of equipment I've owned in the last 20 years, without any problems, including my 1990 GMC pick-up truck with 400 k miles on it. ;)

Ic, so a map with a temp sensor would be the most effective? It's been a while, but I think a map was like $50 and they lasted longer. I dunno, I still prefer a carb. They work, then 10 years later they still work. If they need a complete rebuild you're lookin at about $50 and a few hours work.

Yeah, but with a carb try cranking anywhere near the horses out of an engine like a lambda controlled fuel injection system, and not to mention increased fuel mileage and improved air quality.

Peter

Yeah, you go over to Germany and can find cave paintings of carbs! Sheeesh, get with the times!

Gilly

Yeah, I bet Germans have no clue what a carb looks like. Mileage and pollution maybe, but I'd compare power any day. I tried a 900cfm Holley EFI for my chevota once. Mileage dropped 20%, and HP dropped even more, very dissapointing. After a month trying to get it to run like my carb I sent it back. I'm sure a real EFI would have been different, but beat the power of my carb? I doubt it. Cars I've dumped because of $$$ EFI trouble: Toy Celica, Honda Prelude, Toy 4X, and 300ZX. The EFI on my bmw works, but barely (it's gone soon). My old benz seems to run ok, but puts out 10 times the hydrocarbons it's supposed to (going soon too). Cars I've dumped because of a carb: None.
The computer and EFI are the only things that makes me nervous about my latest Benz. My other vehicles are all carburated and never leave me stranded. I know, behind the times, but I've been burned so many times it's hard to adjust uc.

I know many many people will argue the horspower issue with you. I know there are plenty of drag racers who would say you are a fool. However, you are correct about getting better mileage and lower emissions from an EFI system.

Actually I thought I'd take more heat from you guys over that carb comment. Give it a little more time I guess.
I know efi has the potential to beat a carb, I just think we’re still waiting on a management system to make it happen. I don't want to know how much it would cost to replace my carb with an equivalent efi system, I doubt one exists anyway, so I still believe the carb is the way to go for raw HP.
I’m bracing for the abuse to follow, no foul language please...;)

Autozen: Help me out here if I’m wrong, but Lambda means a typical closed loop system correct? From my semi limited knowledge, efi cannot make good full throttle power in closed loop. And I think it may even overheat the ex valves if you try it (educated guess). From what I understand, the O2 sensor cannot accurately read the mix needed for full throttle, so it goes into “open loop” mode. Open loop is programmed from the factory to dump X amount of fuel into the motor, and like a carb, this mix is probably not correct.

Chevota,

I promise; no abusive language. Hopefully we are too civilized for that here. That being said, you keep saying you put EFI on your car. I don't know how you can do that. It is all built in. Are you talking about installing one of the last American holdouts to keep from joining the rest of the world? Are you talking about Throttle Body Injection? I don't consider that fuel injection. A cheaper version of that is used all the time in shops to move cars around with a dead fuel pump. You get an apprentice to sit on the radiator support and continually spray carb cleaner down the air horn. A true fuel inj system be it CIS or EFI is built into the engine. You mentioned Toyota. Have you ever looked inside the plennum chamber of a late model Lexus V/8. There is another small throttle blade for each cyl. Man, do those cars scoot.

The lambda system has circuits built in too take wide open throttle into account. The engines don't necessarily operate in open loop unless you have a sluggish oxygen sensor. When you punch it to pass, extra fuel is supplied to compensate for the big hole you created in the intake manifold with the wide open throttle. You are not running rich at this point because you are supplying air also. The mixture should be close enough to that stoic thing that lambda can send a signal to trim the fuel for optimum power. I am not an engineer so don't hold me to exact details. This is just my basic understanding of how the systems work in general.:p

Peter

Yes, throttle body injection is what I tried on the chevota. It was somewhere between the carb cleaner inj and a carb. It's supposed to be a great setup, but it didn't like me n I didn't like it.
If you're not running too rich for the O2 sensor, then you're not making full power. The sensor tries to make the mix ideal for emissions which are too lean for max power, and from what I've heard, too rich for max mileage. When the computer goes into open loop mode it’s spraying fuel from a “map” generated at the factory that says; “well, gee, hmm, were at 3Krpm, full throttle and 195degrees, lets dump X amount of fuel.” The fuel map in my Holley system was programmable from a laptop in the field. I seriously doubt that’s the case with a typical car. That system, and every efi car I’ve had, can’t operate fast enough to be as responsive as a carb. My efi cars have all been very sluggish at low rpm’s or of the line, and my Mercedes are among the worst offenders.

Re Lexus: Sounds complicated and expensive. I would break it for sure.

since thread was bumped her is my say.
My AMG C36 has efi and AFRs on WOT are dead on all the way to the 7k redline at 12.6 to 12.8 which on NA is just the best range to make hp. Prob here is that if u mod ur car it is hard to increase fuel to match and here carbs and cis would be easier to work with.