backfiring/fuel cut problem

[spammy123]

ok so after takin the car out for a while a few nights ago and runnin it pretty hard, the next day it started sputtering/backfiring/ occasionally hitting fuel cut. i also noticed it started makin this high pitched whistle noise as i started to give it throttle before it starts backfiring and such. so i thought it might be i had a bad plug, i replaced those as well as the tube that goes from the air intake back to the BOV to recirculate it becausae that had a crack in it and obviously was leaking some. that didnt fix it. i felt around and felt air coming out of the downpipe where it connects to the exhaust inlet and so i made a gasket and slapped it in there and no longer do i feel the air leaking out of there but i still am having the problems and i still hear that high pitched whistle noise, im almost certain that noise is from a big leak somewhere but i feel around while the car is idling and cant feel any air coming out of anything and nothing is obvious. Any suggestions?

 

[the_mork]

A boost leak test is the obvious first step http://www.vfaq.com/mods/ICtester.html

My tester was completed in about 10 minutes with a 2" rubber pipe and PVC end cap from home depot, I use a PVC ring and a screw in cap with the square for a wrench at the top which separated the valve stem from the body of the tester more and makes it easier to use, with a t-25 you will need to push the body all the way onto the turbo past the shiny part that your intake pipe attaches to for a good fit but this is easier than using a smaller hose and trying to stretch it to fit.

After that, you could try spraying ether/starting fluid/carb and choke cleaner around your engine bay a little bit, if the car tries to die or if the idle picks up speed look in that area of course it will pick up speed around your air filter. Your ECU may also be compensating for something, I don't know if it's entirely normal but my car takes up to a couple of days to hit a smooth idle if I change something or reset the ECU.