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Discussion Starter · #1 · (Edited)
I Decided to perform a little test out of curiosity. I had a 3 inch intake that I put on my car(that wasn’t the thing being tested.) as well as an oiled filter.
I had the oiled filter because my friend wanted one and gave me money to buy him one. I didn’t argue; I have my own AEM dryflow.

So, I installed the 3” intake along with the oiled filter. I cleaned the MAF prior to installing everything, and using my AEM F/IC I cleaned up the MAF sig and fuel trims stayed between +/-3.0. I ran with this setup for about 3 weeks driving to and from work which is about a 70 mile round trip each day for 4 days a week.
Last weekend I went on a long trip to VA Beach, Norfolk area which was a 4-6 hour drive each way, approximately 150-200 miles each way. I put the stock air box back on as to prevent any issue, etc. prior to leaving for the trip(I even went as far as putting on the stock elbow for the first time since buying the car). I zeroed out the map on the F/IC to make things stock again for the stock intake, reset the ECU of the car and once the intake was back on. Everything was great!

A few days ago I notice some issue with rolling on the throttle in a higher gear with low RPM. I began watching the AFR gauge and noticed the AFR’s getting very lean upon partial throttle at low RPM and higher load(20-30% throttle). Likewise, when idling the AFR would drop down to 16-17 for a few seconds before coming back to around 15.2.
The feeling would be similar to a misfire/bogging; It would get very choppy before smoothing out around 4k RPM. Throttle response was also delayed.
Now, to clarify, when I switched back to the stock intake I DID NOT clean the MAF.
The whole time the fuel trims were in check and at the time I last checked they were at LTFT=1.8/STFT=0.8

Three days ago I Pulled the MAF and cleaned it off (i did not reset the ecu) and there was immediate improvement. Greater throttle response, Smooth roll on throttle, smooth when increasing throttle while rpms are low in a high gear.. AFR's are back in check, fuel trims have stayed the same.. After a few days of driving there are no issues.

To sum it up, i am contributing the following issues to the oiled filter which when i would touch it would come off looking dry on my fingers, however upon closer examination there was visible oil residue on the filter.

Just felt like sharing. One of these days I’ll try and reproduce this with another oiled filter just to test it out. Moral of the story, Don’t use an oiled filter! Just thought I’d share my findings.
 

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I have always been a big advocate of advising people not to use the oil gauze filter for a long time on this board. There was so much debate on this but my findings also showed that those gauze filters also let in more particulate. It was also proven to cause MAF irregularities on Bob is the oil guy and K&Ns response was not to oil the filter too much. I believe after trying many of the materials that foam works the best for flow and protection .
 

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Discussion Starter · #4 ·
I have always been a big advocate of advising people not to use the oil gauze filter for a long time on this board. There was so much debate on this but my findings also showed that those gauze filters also let in more particulate. It was also proven to cause MAF irregularities on Bob is the oil guy and K&Ns response was not to oil the filter too much. I believe after trying many of the materials that foam works the best for flow and protection .

I remember reading somewhere a comparison of all of the filters/filter types a while back.. i don't know if it was on this forum or another. The comparison wasn't with CAP and his flow bench. Anyways, if i remember the drawback of our stock intakes isn't the airfilter. As i remember the surface area of our flat Airbox type filters is just as much, if not more than the standard cone type filter. Not only that, but it protects it from the engine heat. The bigger factor as most know and will agree and CAP will eventually stand up and shout, but it's the MAF readings. As what i performed showed us is that TO much oil on an oiled filter will cause misreadings and skewed results due to the oil and particle buildup on the MAF sensor wires.

AS My AFR was showing i was running lean during partial throttle and low RPM it would tell me that the MAF was only picking up when there was a decent air flow, thus tellign the ECU to cut fuel because there was "Less Air flow".. These go hand in hand.

To debate if the air filter is good, i believe it could be. One of my friends recommended putting the end on a shopvac and sucking through that for a few seconds(as long as the filter doesn't collapse) to remove extra/excess oiling.

To counter what i just stated, I believe oiling the filter could provide a substancial decrease in small particles entering, the downside is still the fact that it is oiled.

For me, i'll stick with foam in the stock inbox
 
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