Maybe some of you have better clues than me.. I am getting pwr cuts from 6800rpm to 7000rpm. This happen only while car is under boost (5psi). During the pwr cut, I can see the boost pressure remains stable at 5psi. After the motor gotten itself over 7000, it regain full smooth pwr till I let go of the throttle. When I push it w/o the boost, it will spin pass 6800 to 7000 smoothly.

The motor max boost is 5psi. I know I have enough fuel as tailpipe emission test shown rich. I have new fuel pump, stock injectors, stock fuel pressure, RX7.com exhausts, stock airbox, fuel cut defender, all engine electronic are working (as far as I can tell...) This is not a ported motor.

Any idea what else I should check?

 

What gauge are you using to tell your intake pressure? Aftermarket?

 

on stock tii engine i dont' think you're suppose to gain much power after about 6500 rpm............

 

This is not a stock S4 motor. All the components are lighten from the inside. Have VDO boost gauge to confirm the 5psi boost pressure.

 

Hmmm... I would have guessed fuel starvation, but that would cause more then just one problem. Expecially under boost.

Do you have an AF gauge? What are the readings?

 

The AF gauge shown I'm at full rich but I don't trust it. Once I'm over 7000rpm, I get all my power back so I have doubt its fuel starvation. Motor push hard right into 8000+rpm