Michael Filippello

I have a boost problem that I have not been able to solve. During modetate acceleration i get a fluttering sound and my boost gauge shows that the boost is fluctuating around 0 psi. This only happens if I am going through transition with low boost. right around 4200 rpm the boost starts to pulsate. If i back off and then jump back on the gas, the car resumes propper boost and accelerates normally.

If I accelerate in vacuum I have no problem. If i accelerate hard with the pedal floored I have no problem. my boost curve is very good with minimal drop at transition. I get no fluttering below transition and no fluttering above transition. The only way this happens is if i am at light boost going through transition. If I am around 3-4 psi and then go through transition the boost drops a a few psi as the secondary turbo comes online and then doesn't recover propperly. It starts to pulsate rapidly around 0-1 psi. If i let of the gas just a bit and then reapply the gas it stops fluttering and starts to build boost again. It works fine under full acceleration.

Any help would be greatly appreciated. Other than this the car is working great. I put down 360hp at the rear wheels a few weeks ago at 12.5 psi. It never did this during pulls on the dyno and my transition under wot has no dip. It almost looks like a single turbo graph.

thanks
mike

HUGH

Perhaps the secondary turbo is cooked. Mine felt fluttery at high boost and the power was down a little.

Michael Filippello

Both turbos make good power. This is a transition problem, but I can't figure out what exactly. I even switched to non-seq for a while and It disappeared. As soon as I went back to seq. it reappeared. I don't know if it is the turbo control, the charge control, the charge relief valve or solenoid, or something else. When the fluttering is happening I am only at 0-1 psi in the middle of transition. It's as though the car is stuck in the transition phase. If i am accelerating hard through transition, everything works fine.

Wade

iTrader: (1)

This is normal, stock cars do it.

Wade

nocab72

Your primary needs to be making 8psi @ transition for a proper transition to take place. There is an/are actuator(s) that needs both vaccumm from the hose-mess and boost from the primary to properly open/close the butterfly(s) for the secondary to come on ...

If you aren't "on it", why wouldn't you shift before transition anyways?

BTW: It is a weird a$$ feeling, the fluttering, and strange sounds your CRV/BOV make, etc when you are at partial < 50% throttle and cross transition. I just try to drive so I don't cross transition unless I'm @

WOT BABY!!!

K

Hyperite

The second turbo does not come online unless the primary is already making 7psi.
~Tom