jay....

ive fitted a dumpvalve on my 96turboscoob,its a prima racin piston type,it works fine and the car runs fine but i get small back fires every now and again wen i change gear,is this a problem????? cheers

The_Judge

I'm assuming it's a VTA design... in which case, the pops and bangs are caused by unburnt fuel igniting in the exhaust.

Debatable. Those running VTA dump valves will say...

"No, not a problem at all. Enjoy!"

...whilst those running recirc dump valves might say...

"Possibly, as the unburnt fuel is caused by an excessively rich mixture on gear change, due to the ECU being fooled by some of the metered air being "vented to atmosphere", rather than "recirculated" back to the induction tract, and so the injectors inject an amount of fuel for an incorrect amount of air, which in certain circumstances could lead to bore wash..."

You pays your money, you takes your choice...

BTW, Mikey if you're reading, you'll notice I provided information from both sides of the coin...