Originally Posted by cleansubaru
hi i like your info from all. this is my first add to any posts . i have a 97 legacy out and had 95 leg , both stuttered at 1800 -2500 rpm . does this co-realate ?
also it currently hums out of air box. any ideas? thanx
Your issues are likely different than the issues experienced by the 2005 Legacy GT and Outbacks Turbo motor owners for which there is a Subaru of America ECU reflash. That is the central topic in this thread.
Throttle body cleaning may help should resolve some of the stuttering your experiencing. Check this link...
Also, the ground mod may also help with hesitation at the RPM range that you're experiencing problems. Here's another link... http://forums.nasioc.com/forums/showthread.php?t=183280
Believe you have the airbox (with filter inside) and a direct piece going from there to a torque box with a little stubby section sticking out of that airway between the filter box and the torque box. If so, and the initial part of the intake system (the plenum ahead of the filter box) has been removed, then the stubby is probably where you're getting the "hum" sound from.
Either re-install the initial intake piece (huge gob of plastic piping/boxes designed to reduce intake noise and smooth out the intake air turbulence) or replace the pipe (with stubby) between the filter box and the torque box with a direct pipe with no stubby. Air across the stubby (like blowing across the top of a bottle) is likely causing the hum.
If you are not setup like this, then check all of your piping connections between the filter box and the throttle body intake and use some carb cleaner spray along the length of your intake to see where the air leak is coming from. Just spray the carb cleaner on the intake and if the noise changes or the engine rpms increase/decrease, then you've located the leak. Also, check the carb cleaner on an out of the way spot first to ensure that it doesn't hurt the plastic on the intake.