Air Passing back through turbo?
 

I've just fitted a FMIC with a Forge Dump Valve. When coming off boost some of the air is dump back through the turbo and making a chattering noise. Which I'm assuming isn't good for the turbo. So, what can I do to overcome this? Would a bigger dump valve solve the problem?

Thanks
Chris

It does sound like compressor surge.
Try either a softer spring (you can get a full set from forge for (£10-15) or another BOV...

What turbo?

Simon

i.ve the same problem with a hks dump valve

ive the same problem with a hks ssq i think a lot of ppl get this wen fitting a fmic. any suggestions on how to overcome this ?

I've experienced this as well. Fitting a softer spring will help dump more air and reduce this effect; however, it can also mean that the pickup becomes more laggy when planting the throttle in between gear changes (when the engine is revving hard and the turbo is fully spooled up). I have a Forge dump valve and am just about to experiment with some stiffer spring to try and reduce this effect

If it is TD or Garrett turbo then enjoy the noise.. shouldn't cause a problem.

Simon

It's a TD05, but the Dump Valve is fitted on the turbo side and not the inlet manifold side. Does this make a difference?