Greddy Profec B Spec II installed....Q's

[CelicaST-162]

I spent the day installing the Profec B spec 2. Install was straight forward and the car responded well. Now, certain pulls I can feel the car has a fast misfire, or machine gun like sound from the exhaust. If I turn down the GAIN % it goes away. My concern is is this normal with Boost tuning? Or should I stop now and upgrade fuel and AFC and such? Was the car detonating?

The car was running at factory controlled 12.5 psi before this unit was installed, I set it to a conservative 15psi.

This is on a Toyota Aristo TT, JDM of course. Complete exhaust, intake, Split Second BCC if this info helps.

Figured I would post on here as well, I know there are guys that are savvy with this stuff....

[RickDaTuner]

Sounds like the car is reaching the boost limiter and cutting your spark...

[Supa Dexta]

Gotta start with the basics man... Timing, plugs, wires, fuel delivery.

[peterparker]

detonation?

[T-Dubbs]

u need a HKS FCD
(fuel cut defender) to run that kinda boost.
its just fuel cut, nothing else. had the same problem when i cranked the boost in my soarer

[tabouli]

My guess is the obvious choice ... detonating.

All of the above posts are relevant though. We need more information to properly diagnose the problem. Post specifications if you want help. Are you throwing any CEL codes? What parts are on the build? Fuel octane level?

Yes, it's normal for boost tuning. But only to a certain extent.
Don't harm the motor once a problem becomes apparent!