GT-X FC3S

Lately i've noticed my boost is extremely strong up until 5200 rpm, in every gear. I have a FCD, DP, MP, and catback exhaust. I also have 720cc secondary fuel injectors. I do however have stock intake, with a k&n drop in filter. Would the intake be why it's not boosting anymore after 5200 rpm? As in it's not getting enough air, like not a good a/f reading? Any help please!! those extra 2k rpm's are vital to me with boost!

thanks

NZConvertible

Stock turbos drop off a bit towards redline, as they are optimised for mid-range power to make the car more usable. How much boost are you running? With a full exhaust I'd expect you're having boost control problems. The stock wastegate port is very small and can't cope with many mods before boost creep becomes a bif problem. More than 10psi on the stock turbo isn't a good idea if you want it to last.
The biggest problem I can see is those secondary injectors. You don't mention any way of controlling them, so you'll be running far too rich and loosing power. You need a fuel computer of some kind
to tune them down a bit.
As for the intake, unless you do something about keeping the boost down, I'd leave well alone. The stock airbox and turbo inlet duct are quite restrictive so replacing them will make any boost problem worse.

GT-X FC3S

I used to have Bonez intake, and it would never do this. Now that i have the stock air box, it does. My friends FD has the M2 intake with the cold air box and all that good stuff. He said his did the same thing with it...it's like it acts as a stock air box but with just the two kn filters in it. Anyway, he said when he took off the top lid to the m2 box his boost kept going strong. So, i'm going to try something, I cut the "mazda" part out of my stock air box and i'm going to see what happens. If nothing, i'll prolly just get a new intake system.

GT-X FC3S

I cu the top of the air box out, and it's cured. i get full boost now all the way to redline, the car runs real strong. Oh and NZConvertible, i run right around 10psi. You're right, i need to get something to control the fuel somehow, and i need to get a a/f gauge to see how rich i'm running i guess. Thanks for the help.

NZConvertible

An A/F gauge won't tell you how rich you're running, they're not nearly accurate enough for that. You need to get onto a dyno for that. But you will be running too rich, so you might as well just get something like an S-AFC and get it dyno-tuned.

GT-X FC3S

Yeah, i plan on it, thanks again.

IWNTA20B

As NZ says, you need to control the fuel. You may be running too rich. Did you re-wire the fuel pump?
You'd be surprised what voltage you are getting at the pump. A few years ago I accidentally found this problem. The fuel pump was getting about 10V and less at night.

GT-X FC3S

Yeah, i plan on it, thanks again.