mattj Posted May 18, 2013 Share Posted May 18, 2013 Just a random question here that someone may know the answer to, I have a SR20 motor and I took the air filter off to clean it then tried starting the motor with no filter on and it started up fine but wouldn't idle, it just stalled out. When I put the filter back on it runs fine. I am assuming this is all to do with the air flow meter but wouldn't have thought it was smart enough to know that there was no filter in place. Anyway it isn't a problem or anything I just wondered if anyone had this problem before or knew why Cheers Quote Link to comment Share on other sites More sharing options...
thegreatestben Posted May 18, 2013 Share Posted May 18, 2013 I think quite a few AFM setups require an air filter to regulate the air flow. From memory RomanV had issues with his Beams 3S setup, he made an "air straightener" by hot gluing a bunch of straws together and placing it in the mouth of the AFM. Without the filter there is turbulence causing shit readings. I've also found removing the air filter on some forklifts at work makes them run like absolute arse, these have been LPG and Diesels. Quote Link to comment Share on other sites More sharing options...
twosmoke Posted May 20, 2013 Share Posted May 20, 2013 . Quote Link to comment Share on other sites More sharing options...
keltik Posted May 20, 2013 Share Posted May 20, 2013 Step number 1 in diagnosing air flow meter problems on a Subaru is to unplug them. ECU will go back to running MAP based fueling. If problems go away - its probably the AFM/MAF sensor causing it. Quote Link to comment Share on other sites More sharing options...
twosmoke Posted May 20, 2013 Share Posted May 20, 2013 . Quote Link to comment Share on other sites More sharing options...
twosmoke Posted May 20, 2013 Share Posted May 20, 2013 . Quote Link to comment Share on other sites More sharing options...
mattj Posted May 21, 2013 Author Share Posted May 21, 2013 As above, no air filter can make AFM's give weird readings. However, I know my S13 with an SR20DE runs just fine with or without a filter, and I have had a couple of different (SR) AFMs on there. It just has a pod filter in the mouth of the AFM and the factory plastic intake pipe behind it. I could be wrong, but it sounds like your filter may be restrictive, causing a lean condition when you take it off, causing the car to stall. What kind of car is this in? It is pretty hard to say without seeing it Car is a S14, has a S13 SR20DET fitted (don't ask me why, I guess someone cheaped out fitting a turbo motor) it has a K&N pod filter on it so I wouldn't have thought it would be that restrictive. A lot of the stuff I read seemed to point at the AFM perhaps being faulty but the fact that it runs fine with the filter on makes me think that it is something to do with the airflow like what thegreatestben posted. However it really wouldn't surprise me if there were that many things wrong with the car that they had somehow combined together to make it run fine. Anyway it isn't causing a problem or anything, it just seemed strange to me, and hearing that your s13 SR20DE runs without a filter confuses things some more. Unless it has something to do with the turbo...... Quote Link to comment Share on other sites More sharing options...
FuzzayD Posted May 31, 2013 Share Posted May 31, 2013 when you say you remove the filter is the air flow meter still attached to the filter? Quote Link to comment Share on other sites More sharing options...
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