I have a CX hatchback and I put an SI intake manifold and a DX throttle body on my car. Ever since I have done this my car is busting up at high rpms. I usually rev my car to 5500 when it was stock. Now, the low end feels much better but at 4200 rpms the car slows down and if you keep it at WOT it starts busting up around 4500 rpms. I think I may know the problem but I want to make sure first. I still have my stock injectors and from what I read they are different from the SI and DX injectors. Should I put those in to see what it does? Also, should I swap my fuel regulator from stock to the DX or SI one also? Thanks for any help.
~Chuck

 

busting up... what is busting up?

 

Seems like it is hitting the rev limiter or something but I know it is not the rev limiter. Almost like it is just shaking very bad or something. Hesitating or something. You know, busting up. Haha. Thanks though.
~Chuck

 

man its time to swap that cx motor and put in a d16z6 or a jdm d15b or d16y78

 

If I swap anything it will be to a duel cam, the only reason I put this **** on is b/c it was free to me so why the hell not? Got a solution to the problem besides swap it?
~Chuck

 

Bump before I goto bed. Anyone got any ideas?
~Chuck

 

it could be valve float, thats if u redline a lot, because it feels exactly like you're hitting the rev limiter and losing power.

 

if you dont know what valve float is its a high-rpm engine condition in which the valve lifters lose contact with the cam lobes because the valve springs are not strong enough to overcome the momentum of the various valvetrain components or conditions. The onset of valve float prevents higher rpm operation, also periods of valve float will damage the valvetrain.

 

nah i did the same thing... i did it just because the cx was my beater and i had a si manifold laying around... the car is leaning out... like you said, swap the fuel regulators and the injectors. you increased the airflow but, you did not increase the fuel flow. you are robbing your car of fuel, so replace those parts. if you still have the same problem, i don`t know.. maybe its time for a real swap. maybe one involveing two cams a trans and a ecu.. cx`s are tight, crutial weight to power ratio..