About 7k-8k miles ago, I bought a CAI from Racing Dynamics for my M62TU engine. It came with a K&N cone type filter. Yesterday, I opened the hood to see that the piece of metal glued to the end of the filter had fallen off, leaving a large unobstucted hole at the end of the cone. I went back inside and got the old airbox, and put it on.
I drove like this for about 80 miles, and today the car died at a stop sign and cel came on. I checked for leaks, lose vaccum and intake hoses etc. Nothing, but the car died after idling for a few seconds. I made it to an Autozone(the car didn't die at red lights, if they were far between, but died at every light on the way home:3 miles, 8 lights).
I thought MAF before he even plugged in the Autotron??(the orange one). As soon as it registered the code the screen said MAF something. The guy said he's heard of the same problem on other bmw's, and cleared the code. As soon as I started the car, the cel came back on, and it died.
Anyway I read a thread awhile back, in which a few people said that the oil in the K&N filters can destroy MAF's. I wonder why it happened within 100 miles of removing the K&N. The stock airbox i put back on was clean, but the filter wasn't new. It is probably 15-20k old(Mann), and I tapped/vaccumed it before installation.
I will try cleaning it, but am not expecting much as I just did that about 2k ago. Tomorrow I will swap MAF's with my indy's E38, and see what happens.
There is an article circulating debunking the K&N oiled filter/ruined MAF theory as a myth.
sounds like cleaning may help, but don't be suprised if you need a new one. Symptoms are just like mine when my MAF failed. A new one got it running perfect for me.
over oiling can be an issue.
also, did you take the "grid" out of your MAFS? the grid is there to provide the sensor with laminar flow over it. if you removed that and changed the filter the ECU may have to readjust for the different sensor values.
have you tried MAFS cleaner to rid of any possible oil buildup?
The K&N filter can destory MAFs due to over-oiling. What seems to happened to you could be a variety of things:
1. The oil on the filter killed your MAF. If this is the case (unlikely) simply cleaning it with MAF cleaner should work to repair it.
2. Having a huge open hole on the air intake allowed dirt and debris into your intake and engine. This dirt and debris could also have landed on your MAF, fouling it and hurting the sensor. It may be possible to clean it but its also possible it destroyed the sensor.
3. When you reinstalled the airbox you may have forgot to tighten something or seal something and there may be a major vacuum leak somewhere.
Pretty much you wasted a lot of money on a product with no benefit aside from intake sound that destroyed your MAF and even possibly harmed your engine...
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I'm not endorsing or opposing the use of K&N filters. I am only providing information so you can come to your own conclusion regarding said debate.
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http://www.knfilters.com/faq.htm#27
27. Will a K&N filter cause my vehicle's mass air sensor to fail?
No, it is both impossible and ridiculous.
It is impossible because we know that the oil treatment on our cotton is very small (usually less than 2 ounces). Once the oil is properly and evenly absorbed through the cotton, no oil will come off, even under extreme engine conditions. It is ridiculous, because no dealership or service provider has ever been able to provide us with evidence to support this "myth," and in fact, our investigations have revealed that even authorized dealerships are simply speculating and do not have the test equipment necessary to know whether the sensor has failed or why. It is even more ridiculous because some car manufacturers use and sell air filters treated with oil on a regular basis. There are also major brands of disposable air filters that are treated with oil. We all use oil for the same reason, it helps in the filtration efficiency of an air filter. For more information on this topic including videos, see our Mass Air Flow Sensor Statement page.
Out of the millions of air filters we sell, we only receive a handful of consumer complaints each month that a dealership or service provider has blamed a vehicle sensor repair on our product. We take each complaint very seriously and see it as an opportunity to stop a consumer from being taken advantage of. We investigate the situation thoroughly and take full responsibility for resolving the issue. For more information on how we educate and persuade the service provider to reconsider their position, see Mass Air Flow Sensor Information & Testing. We are so confident in our ability to resolve these situations and to help a consumer fight back that we offer our Consumer Protection Pledge.
As a result of our standing up for consumer rights and providing assistance to resolve a disagreement, we have had over 100 actual sensors sent to us by dealerships who claimed our product had caused them to fail. Microscopic, electronic and chemical testing revealed that none of the sensors were contaminated by K&N oil (K&N Detailed MAF Sensor Test Results). What is perhaps the single biggest clue to what is going on is that over 50% of these sensors were not broken in the first place for any reason. Click here for more information on how this may happen.
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Here's an interesting video on the subject.
http://www.knfilters.com/MAF/2MAFSensorVideo.htm
Last edited by jamesdc4; 01-10-2010 at 09:42 PM.
A few things to consider:
1. I have been under the hood a lot in the past few days replacing tensioners, and a radiator drain plug with multiple fills/bleeds. I saw the filter had broken, before I drove it, so I wasn't driving around with a hole in my intake.
2. The filter is only 7-8k old, and hasn't been reoiled ever. I read in a thread that typically the issue is over oiling after cleaning a K&N.
3. No I did not mess with the grid in any way, and I just used the CRC MAF cleaner about 2k ago(I'm doing it again now, but again not hoping for much.
And blackxs, the thing cost $200, so I didn't really waste a lot of money on it. As far as my engine goes, I've had the VC's, intake manifold and valley pan off, and everything looked great. Also, when my Indy did my VANOS job he said that it was actually one of the cleanest engines he had ever seen. I appreciate your concern for my car though, and once again you end a helpful post with a SA comment.
i'll believe it 100% when I see 3rd party results.
abundance of oil + high-velocity air stream + obstacle in air stream = possible coating of obstacle.
again, some MAFS cleaner would most likely remove any [oil] residue thus remedying any issue.
check for loose/broken connectors and/or wires.
Last edited by mattmartindrift; 01-10-2010 at 04:36 PM. Reason: Automerged Doublepost
I'm not a believer in the oil/filter conspiracy theory. Is there oil in the intake tube? If so is it filter or motor oil? Also the OP has '99 car. Is the MAF just an old, worn out part? Is the old MAF just dirty from the hole?
I just cleaned it with CRC MAF cleaner, and it died again about 3 seconds after startup. Same thing three more times, but then it idled w/o dying, and I took it around the block a few times. I let it sit at stop signs for a while and it didn't die.
However; the cel is still on. It should reset itself if the MAF were clean and okay, right? I guess it's probably just an old part(I don't know if it's ever been changed). Engine has 130k, so I'll just replace it.
It might just be a coincidence too.
I have had and continue to use K&N filters in other vehicles and have had no sensor issues.
While the K&N statements may be true for properly oiled filters, if someone over oils their filter it can cause the MAF to read improperly. This DOES NOT KILL it. It just needs to be cleaned.
The OP's MAF may just need to be cleaned as well.
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If you check the provided links you will find that they actually performed testing by dipping the MAF in air filter oil, and it did not damage the element in any way, the MAF functioned perfectly after being cleaned.
They have tested the filters at far beyond the flow capacity of any street vehicle and found no contamination of the MAF element, this was confirmed by a second party who did their own testing as well. If you search you will find my past information on this topic. I have 70k on an K&N on my 528 with no issues whatsoever.
This actually sounds like an electrical issue of some sort in the wiring from the MAF.
Last edited by NNY528I; 01-10-2010 at 10:05 PM. Reason: Automerged Doublepost
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Thanks for the replies everybody!
I ended up just purchasing, and installing a new MAF and stock Mann air filter, about a week ago. I still had the cel light, so I took it to my Indy, and reset it with a Peake tool. The car has been running great ever since.
Maybe there was a slight film of filter oil on the MAF, and when I put the old stock filter on(even though I cleaned it as best you can a paper filter), some trace elements of crap got stuck to the MAF, killing it, maybe it was just an old part, who knows???
Anyway, thanks!
Oil is an insulator not a conductor. No way for it to make an MAF fail. That's absurd. What if you drive through dense fog and rain, you know the MAF gets wet and does not fail.
I feel the MAF's fail because they are an older tired part, and the increased air flow causes the MAF to work harder and draw more current. More current draw on a old tired part = part blowing.
So in a sense the K and N can cause a failure but through a different mechanism, that's no fault of the filter itself.
First rule of politics - the voters don't decide the election, the counters do.
The appearance of the Law must be upheld, Especially when it's being broken.
I had similar symptoms when a cam sensor failed. Cheap fix but hard to diagnose without a scan tool. Just another possibility.
I can tell you fact they are a big no, no on a diesel. 6.6L pulls a lot of air and the MAFs can become coated and in cold weather they give up. Tons of tests done on forums to confirm this.
Just find a really good stock filter. The one on my truck is a Donaldson buts costs $60. Trust me though you have never seen anything better and it flows real well too as backed up by testing. Wix Gold, Donaldson would all get the nod over K&N anyday and I think that K&N is just a bit of a gimmick.
This is exactly why I only use K&N direct replacement drop-ins on my 2002 M5. When you start messing with cone filters that come with "after market" CAI kits, problems usually arise. Like the car running lean in the upper RPM range... !
Another vote against K&N killing mafs. I've run on a K&N on my Camaro for 8+ years total with 6 of those having a blower too. Part seems pretty tough.
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