Forge BOV not holding boost?

[D1andonlyantman]

Hi. When I bought my 9 I was getting really bad cavitation when letting off the throttle. I bought a forge DV (because I had one on my old LCR which worked nicely) and the problem seemed sorted, the recirc was nice a smooth. Recently I've had quite a lot of work done (cams, rods, intake, EBC, turbo elbow, remap) and now when it's building boost I can hear a sort of pulsing fluttery sound. It's more noticeable in the higher gears. The tuner who mapped it said it boosts to 1.8bar and holds at 1.6 on his external boost gauge he uses for accuracy. When he was looking over the car before the work was done he said he noticed the forge DV was on the wrong way. I fitted it and it was working fine but he's a well known tuner so I didn't doubt it. Firstly, is it possible the DV was on the wrong way round which made it harder for the piston to be pushed open, therefore making it hold boost better? Secondly, I've heard of people removing the DV altogether. I'm no professional but I don't see how that's a good idea, but could I block the DV holes and then go for a quick drive and if the noise is gone I know it's the forge DV not holding boost, or would that be bad for the turbo because it couldn't recirc?

Thanks

 

[sponners]

Take it off and block the holes to test it, it will be fine.

 

[D1andonlyantman]

Wicked I'll give that a go. Thanks

 

[D1andonlyantman]

Bit of an update. I tried bunging the DV hose with a few different things but nothing I had at the house worked, so after giving it a bit of thought I decided to try turning the DV back around, because when it's that way the boost pressure is pushing on the side of the piston rather than the bottom so it shouldn't push it open as easily, and since then the flutter is much better, and the dumping is much more consistent and smooth. One more thing. Seeing as it looks like the DV might have been slightly opening at times during mapping, would that affect the AFR/Map?

Thanks

 

[Andy6]

Have you got some sort of boost gauge? I'd check boost pressures with the DV fitted in both orientations to see if there is a difference. And is there any difference in performance when changed around? I wouldn't have thought it would affect the mapping of the car as the injectors are being told how much fuel to put in based on the MAF and MAP sensors, under a variety of condition such as load, RPM etc etc.

 

[D1andonlyantman]

I haven't got a any gauges yet, that's next on the list. There's certainly not a massive increase in power if any at all, but my car is fairly modded and I think 10 or 20hp (for example) would be hard to notice without some proper way to time myself. It's not about the power anyway tbh, I just want to know the car's running as it should. I prefer the way the car sounds with the DV this way round, it just sounds less busy, especially when I'm varying the amount of throttle there is and the boost is very up and down, so I think I'll just ring the tuner and find out if me possibly having a leaky DV when mapping would have made any difference to the map. You're probably right but id like to hear it from the guy himself

 

[sponners]

If the valve was leaking when it was mapped then the map will be off. Take it back to your man for him to check and tweak the map.

 

[sponners]

as your DV is a forge get in touch with their customer support, you might be surprised at the outcome

 

[Andy6]

Like I said, a map is basically how the car reacts to a certain set of conditions, boost pressure and Mass air flow is just a condition that can vary, however if there is a leak after the MAF it may not aspirate properly even though the MAP sensor should compensate. I would still definitely get it checked over though.

 

[D1andonlyantman]

Ok, thanks, I'll get in touch with him when I'm back off holiday

Cheers