BPV issue

[Darth Vader]

Now that I have a boost gauge, i can confirm an irritation my butt-dyno has told me about since I got this car. It seems, when in light or small steady state throttle conditions, like around town or cruise, the bpv opens, right at around 3000 rpm, making the car feel flat around town. If you get further in all feels fine and it makes max pressure as it should. The whoosh sound of the engine changes note and the the boost gauge verifies this is happening.

I can further verify this, as the problem goes away if I disconnect the BPV but, the car's too smart for that and caps me at 9 pounds under those conditions.

Now, I don't have the money to toss on an aftermarket valve right now. Do all these cars do this or is mine just a bpv lemon? Anybody got a known good stocker if the latter is the case?

 

[matsuda]

Now that I have a boost gauge, i can confirm an irritation my butt-dyno has told me about since I got this car. It seems, when in light or small steady state throttle conditions, like around town or cruise, the bpv opens, right at around 3000 rpm, making the car feel flat around town. If you get further in all feels fine and it makes max pressure as it should. The whoosh sound of the engine changes note and the the boost gauge verifies this is happening.

I can further verify this, as the problem goes away if I disconnect the BPV but, the car's too smart for that and caps me at 9 pounds under those conditions.

Now, I don't have the money to toss on an aftermarket valve right now. Do all these cars do this or is mine just a bpv lemon? Anybody got a known good stocker if the latter is the case?

Are you really experiencing drivability problems?
I'm not sure what you mean by "feeling flat" during light throttle conditions.

BTW, if you disconnect the BPV, it will open at WOT and effectively limit the boost pressure.

 

[Darth Vader]

Yeah, it's a driveability issue. It hits 3K at light throttle, the tone of the intake sound changes and the car feels flat, like a carb car without enough pump shot. The boost gauge shows the vacuum reading increasing during this period. Get in deeper and it picks up fine but, it's annoying to drive around like this.

 

[derspi]

Wait, are you still running the Home Depot intake?

 

[Darth Vader]

Nope, AEM CAI.

 

[Wurf]

"like a carb car without enough pump shot"

I know exactly what you mean by that! Take a look at most dyno sheets from these cars and they typically show max boost around that RPM. I think you're only choice is to try another stock BPV if you can get one from someone here, or hold out and save for a Forge or something.

 

[MSMS3]

Darth, you've peaked my curiosity. I'll hook my boost gauge back up tonight for a highway cruise. I don't run it except for testing. I'll play with light throttle boost at and around 3K as it comes up on boost and see what mine is looking like, since I too have the stock BPV. I'm not noticing anything like what you describe, but I'm curious about what the gauge is showing.

Obviously the engine will not build much power at 3k when it is cruising and off boost, but it should ramp up boost pretty well by that rpm point when you toe into the throttle. Our small turbo does not have much turbo lag, but I would think that still it's going to seem a bit flat coming off light throttle and up onto boost until you give the boost a chance to turn that compressed air charge into some power. Interesting question.

 

[coyfish]

Hmm what do you mean by the bpv opens ?? What happens if you cruise control at 3K rpm ???

 

[Darth Vader]

Because I have a CAI, I can hear the intake quite distinctly. The whooshing sound changes note slightly and the boost gauge drops back deeper into vacuum, indicating to me, the bypass is opening, bleeding off manifold pressure. It does not do this when I disconnect the BPV.

Never tried it in cruise....

Thanks, MSM3, I'll be interested in what you see.