I took this video on my way home from work today. Throttle at 3/4. It seems when I am under load the turbo pressure drops and rpms drop at around 3k-4k.

Is this a wastegate issue? an ECM cutting the fuel to prevent over boosting?

This is freshly rebuild turbo. Maybe noteworthy, I pulled a P0133 code after about 60 miles of driving, coincidence?

 

Nope. Seems like normal torque converer action. But maybe not, correct me if i am wrong. I ran it hard through 1st 2nd &3rd. Pulls perfect!

 

how recently have you done a tune up (plugs/wires/rotor/cap)? Keep in mind a weak spark may show up only during hard accelleration.

 

Thanks! The plugs aren't new but they are in decent condition. I will probably get a new set for security. Wires/rotor/cap are newer. Pretty much full stage 0 before I rebuilt the head/turbo.

 

so regarding the P0133 code, that's saying your rear O2 sensor can't compensate fast enough for something off with the mixture. Could be an old sensor or vacuum leak or fuel pressure issue, or if your engine is after market tuned, its out of range for the programming. Assuming your sensor is good and you don't have a vacuum or boost leak, you may want to consider installing a spacer ($30 from IPD) that moves the sensor away from the exhaust stream.

 

Thanks for the info! It probably could use replaced. I am stock too. Im almost 100% positive I don't have vacuum leaks and plan to test my fuel pressure asap. Today on my way to work I noticed it only happens at highway speeds between 3-4k under load(like when overtaking a car). Thanks

 

Just a simple update. I am almost 100% positive my CBV valve is bad. But i'll do some more diagnosing. the fuel is NOT being cut. It wont hold boost in high rpms but picks back up and then falls again. Throughout all gears. So I will be buying a replacement soon. All else is well

 

Fixed! I pulled a CBV from a jy V70. I figured I'd try a cheap swap before spending more on an IPD HDCBV. So after the swap, problem solved. I'm holding boost under any acceleration condition. Verrrry nice indeed. I did notice that my diaphragm was not torn, or rotted, and the spring still seemed active. The only thing out of place, to me, was A LOT of oil on both sides of the diaphragm. So maybe a good cleaning wouldve done the trick. Regardless, for anyone not holding boost without vacuum leaks, look at your CBV, that could be the culprit.

Cheers!