KN filter and MAF....Lost power?

[Gaspasser]

Well, in the past few weeks I have made some changes to my car. The one thing I did noticed is that after the placement for my gruppeM CAI with the KN filter, I felt a LOSS of power or response. After the placement of the AA CAI to the Gruppe and the temp relocation kit, I noticed some gain.

So after reading all the messages about MAF sensors going bad with the KN (wet) type filter, I thinking that this might be my problem. So some questions?

1. Would the new "right out of the plastic" KN filter damage the MAF right away or would I notice a slow gradual lost of power? (I lost mine pretty much right away)

2. To avoid this problem in the future it seems that I should buy new filters every year instead of washing/oil. If that is the case, then how long should I leave the filter in open air prior to install to prevent this from happening?

3. OK so what is it again? What cause this problem?

4. How can I test if my MAF sensors are bad? If the dealer's "voltage" tests are OK, what else can they do to see if the MAF are bad.

Maybe the lost of power is nothing to do with the CAI, but everything to do with MAF?

Thanks for the help. Gas

[Teutonaddict]

Originally posted by Gaspasser
1. Would the new "right out of the plastic" KN filter damage the MAF right away or would I notice a slow gradual lost of power? (I lost mine pretty much right away)

Brand new filter installed on Friday afternoon. Car experienced engine operability problems (knocking, bucking, stalling) before the third run group at a DE on the following day. I'd say immediate.

Originally posted by Gaspasser
2. To avoid this problem in the future it seems that I should buy new filters every year instead of washing/oil. If that is the case, then how long should I leave the filter in open air prior to install to prevent this from happening?

My solution was to return to stock. For the negligible if any gains, I did not want to impede engine operability. I hate when anything takes away from my track time!!

That said, my big brother took my filters and runs them on his 98 540i/6, without a problem. Go figure...

Originally posted by Gaspasser
3. OK so what is it again? What cause this problem?

Here's how it was explained to me. Oil that impregnates the filter from the factory migrates onto the film (or coils--I heard conflicting explanations) of the MAFS. This coating then causes the sensor to misread. In my particular case, when the tech strapped a digital voltmeter across the left bank unit, it showed readings that were way out of whack.

Originally posted by Gaspasser
4. How can I test if my MAF sensors are bad? If the dealer's "voltage" tests are OK, what else can they do to see if the MAF are bad.

I dunno on this one. Again, in my case the voltage readings indicated the problem.

I do recall from the very early threads on the topic that one dealer actually swapped the MAFS from one M5 in for service with those from a boardmember's car. The swap caused the problems to go away, so they left it in. From their perspective, "Bingo!" problem solved. Not sure I want to frequent a dealer that swaps parts without notifying both parties in advance....but that's another topic entirely!

Good luck! Let us know how you fare...

-Dave

[TCM]

I do not think it has to do with the K&Ns at all. While there have been some reported problems (I have had none with mine), your throttle response changed when the AA cai was installed. If it were the K&Ns, I do not think you would notice any change. I have noticed decreased throttle response on some cai's and even some lag. I have a feeling that the Gruppe M intake did not have enough air to suck without the AA cai. Of course, I could be way off base. Please let us know what the end result is.

[gdoan]

Originally posted by Gaspasser
Well, in the past few weeks I have made some changes to my car. The one thing I did noticed is that after the placement for my gruppeM CAI with the KN filter, I felt a LOSS of power or response. After the placement of the AA CAI to the Gruppe and the temp relocation kit, I noticed some gain.

So after reading all the messages about MAF sensors going bad with the KN (wet) type filter, I thinking that this might be my problem. So some questions?

1. Would the new "right out of the plastic" KN filter damage the MAF right away or would I notice a slow gradual lost of power? (I lost mine pretty much right away)

I'm not too sure that what you're describing is the same as the MAF sensor failing/fouling that's been described here and other places. I put a K&N filter in my '02 330Ci - "right out of the plastic". (I didn't notice any real difference - better or worse.) All was fine for about a month and then, one day while cruising, I gave it a little gas and suddenly - limp home mode - no power, ran really rough, etc. Tech at BMW center told me it was the oil from the filter that fouled the sensor but that he wouldn't tell anyone about it and replaced the MAF. It would be our little secret...

I did some net research and posted some warnings/questions over on bmw330ci.com but, couldn't come up with any definitive conclusions.

All seemed fine for a couple of weeks and then I thought I noticed some hesitation. I pulled the MAF box assy out and checked it out. I found a noticeable (to the touch but not the eye) film on the inside of the assy between filter and MAF sensor. I cleaned it out very carefully, screen, sensor, and all (somewhat similar to another post on here, today, TECH: Clean your MAF, don't replace!) and put it back together with the OEM filter. Never noticed any similar problems for the next 6 months or so when I replaced it all with a GruppeM CAI. GruppeM also employs a K&N, wet filter but I checked it often. Worked fine up until the car's untimely demise.

Originally posted by Gaspasser
2. To avoid this problem in the future it seems that I should buy new filters every year instead of washing/oil. If that is the case, then how long should I leave the filter in open air prior to install to prevent this from happening?

Oil doesn't evaporate quite like water. I doubt that this would make a difference - IMHO.

Greg
'03 ///M5 Black on Black Sport
Split Rear Seats
Rear Sunscreen
M Audio (downgrade..?)
Ultimate Cup Holders (they really work well!)
Bluetooth (sitting in the living room...)

[x703jko]

All: Anything that changes the thermal response of the Pt sensor in the MAFS will change its response. The Pt wire in the sensor is very thin and has a very low heat capacity, which means that it doesn't take much of a change in temperature to cause it's resistance to change and therefore a change in sensor output. Since the wire is so thin, it has very little mass. Heat capacity is proportional to mass...anything to change the mass of the wire will cause erroneous readings.

See a related thread that started today (on how to clean MAFSs) for an explaination on how they work.

Jeff

[Gaspasser]

Thanks everyone...maybe monthly cleaning will help. The car is in the shop, but I will look into this.

gas

[Gaspasser]

Thanks everyone...maybe monthly cleaning will help. The car is in the shop, but I will look into this.

gas

[M5Don]

K&N filters "out of the plastic" are sometimes pretty inconsistent in the oil content. Some filters I have seen are fine, while others are grossly over-oiled. An over-oiled K&N will foul the MAF, sometime causing complete failure.
Usually, it is when a filter is cleaned and re-oiled that this happens, since people tend to over-oil the filter.
If you find that your filter is over-oiled, buy the K&N cleaning kit, wash the filter out, then re-oil lightly. You should not get oil covered fingers when handling your filter.
When used/maintained properly, the K&N filters are very good products. (not much gain, but truly a lifetime filter). Monthy cleaning of the MAFs does not seem like an acceptable solution.

As for what a dealer can do to diagnose, I have seen them (pretty often) replace the MAFs with new ones to test the running of the car. If the problems go away, they leave it and bill BMW NA for warranty (or you if you are out of warranty).
I have not heard of (or approve) the swap using another customer's parts though...

Thanks!