JDMSIL80

Here's the deal:

Ive got my Apexi Power FC & Z32 MAF installed & street-tuned using wideband, A/F is relatively stable around 11.5 to 12.

So we dialed in for more boost to 9psi, but the fuel/boost cuts off at around 5000rpm.

Then we tried 10psi, and the cut off came even sooner at 4800.

Basically, the higher boost we go, the lower the cut off becomes. Only at 7psi that I am allow to rev pass 6000.

Im using Blitz EBC to controll boost, not the optional Apexi boost control kit.

According to the Power FC instruction manual, it would work as long as we set the Power FC boost to a level where fuel cut will not occur.

So we followed the instruction and adjusted the boost limit settings on the Power FC up to allow maxium of 18psi.

My MAF voltage peak value is 3V, and injectors duty cycle peaked at only 50%. So Im far from hitting the MAF reading ceiling and max injectors duty.

Now what other causes can you think of that may cause this problem??

FYI, here's my mod list:

Power FC + Commander
Z32 MAF
444cc injectors
GT28R
Blitz ID-color boost controller
Blitz gauges (pres, EGT, boost)
FMIC
Tubular manifold
3" turbo back
HKS filter