BIGBLUE1212 Posted February 8, 2007 Share Posted February 8, 2007 hey everyone, i have a 97 legacy gt 2.5 4at.....when im cruising on the highway and the car gets to around 3000-3500rpm....the engine gets really loud then it goes quiet again.....what does that mean....knock sensor? Quote Link to comment Share on other sites More sharing options...
nipper Posted February 8, 2007 Share Posted February 8, 2007 4 Cylinder Engines have a boom effect. There is a RPM where they suddenly get loud, then get quiet. Its complicated harmonics in the intake and exhaust system. If this just started look at the intake and exhaust system, make sure nothing is broken or loose. Make sure there are no clogs. nipper Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted February 8, 2007 Author Share Posted February 8, 2007 ok.....i just got a k&n filter a little while back maybe thats it Quote Link to comment Share on other sites More sharing options...
nipper Posted February 8, 2007 Share Posted February 8, 2007 ok.....i just got a k&n filter a little while back maybe thats it BINGO! nipper Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted February 8, 2007 Author Share Posted February 8, 2007 so is it a bad thing? Quote Link to comment Share on other sites More sharing options...
nipper Posted February 8, 2007 Share Posted February 8, 2007 I dont like aftermarket air filters. They can contimnate the sensative electronics by letting much more dirt through then OE, and i consider them a useless expense on a daily driver. They get more flow by having larger pores, so more dirt gets by. Its even worse if they are oiled filters. This is not good for an engine that gets over 200,000 of life from a stock air filter (subaru has to be doing something right). Now this is just basic engine physics, not a bad thing, just unacceptable in the NVH that todays drivers demands. If you want to confirm this, put the old filter back on. nipper Quote Link to comment Share on other sites More sharing options...
BIGBLUE1212 Posted February 8, 2007 Author Share Posted February 8, 2007 meh i think the rpms shoot up a bit quicker with this filter...it was actually a birthday present im happy with it...i still have to check that knock sensor to see if its cracked Quote Link to comment Share on other sites More sharing options...
ScoobySchmitty Posted February 8, 2007 Share Posted February 8, 2007 I dont like aftermarket air filters. They can contimnate the sensative electronics by letting much more dirt through then OE, and i consider them a useless expense on a daily driver. They get more flow by having larger pores, so more dirt gets by. Its even worse if they are oiled filters. This is not good for an engine that gets over 200,000 of life from a stock air filter (subaru has to be doing something right). Now this is just basic engine physics, not a bad thing, just unacceptable in the NVH that todays drivers demands. If you want to confirm this, put the old filter back on. nipper I think I killed my old Roo with one I purchased. It was running fine for the longest time...added one of these, then a few months later the head gasket blew. On a 2.2 no less. Quote Link to comment Share on other sites More sharing options...
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