Well on my buddys evo, when i was driving it the other day i tried to do a few full throttle pulls and when i pined it around 3-4th gear it would bogg bad and then backfire (think fuel cut/overboost/ cold air density) and would keep doing that but when i do a partical throttle pull about 50-75% throttle it would pull fine. car has a Turbo xs Mbc, licp, bigger intercooler, K&n typoon intake, and a apexi turbo back exhaust. (no tune yet) wanna make sure its all good to go before tune at ams, any idea's guys?

- Kyle

 

You hit fuel cut. Stay off full throttle until you get a tune.

 

The problem is the typhoon intake there not the best choice for the evo and its in desperate need for a tune,When you go to ams for the tune there sort everything out for you.

 

thought so and the car came with the intake on it so thats why it has it and no need to change it and waste the money and thanks guys just making sure it wasnt a boost leak or anything like that, it will have a upgraded fuel pump also before its tuned. the car is running around 15psi of boost right now and its still overboosting so im guessing its the IL cold air density.

 

Let me know what you find out because I am having the same problem. Car was tunned by AMS, and since the stock turbo died and was replaced (with new OEM one). Summer car ran fine, but now in winter I am having your same problem. The car was also tunned when it had an HKS SSQ, but I recently got a IX DV and its now recalculated to the intake. My theory is a) the old turbo was on its way out and this new one blows much more air, or b) HKS SSQ was not holding boost as good and the new IX DV is way better at holding boost. I am just waiting for the weather to get a little better and get a tune, but any input would be appreciated. Could my theories be correct? Or something else completely is going on?

 

well a buddy and i stoped at ams and picked up some new ngk plugs and we swapped those out and also did a boost leak test and found a little leak at the boost guage T and fixed that then we also crushed the evo 8 metal bypass valve (been told it would hold more boost and sti guys do it all the time). We took it for a spin and WOW the car runs better then it ever did, doesnt overboost or anything anymore we turned the boost back up and she hauls again, The old plugs were ngk iridium plugs and there was a build up on them (ill try to take a pic) and i was guessing there was a weak spark and the boost would blow it out and then backfire well now the car is making a farting noise just baout from the valve around 5psi but still releases the air, was it not crushed right? ill try to take a pic of that too thanks