988wrx

Just fitted a aftermarket recirculating forge dump valve to my my96.

car feels noticably slower now and the engine seriously backfires when lifting off the throttle, also engine hesitates around mid revs.

took it off and put standard dump valve back on and everything is fine!!!

I`m confused, why would just fitting an aftermarket dump valve do this, do i need a remap for it to run fine???

Jim

Peanuts

iTrader: (15)

I cant see why it would run rough, uinless you had mixed up some of the plumbing, but its a re-circ same as OE?
Confusion high

briforbes

Is it definately a re-circulating valve (i.e. doesn't vent to atmosphere and make the "PTTTTSHHH" sound)?

Brit_in_Japan

^^^ what he said.

Backfiring suggests unburnt petrol in the exhaust gases, which is unlikely to happen if you've just replaced a recirc valve. But VTA's dump measured air, leaving an over-rich mixture to pass through the combustion chamber. Are you sure you bought a recirc valve?

988wrx

well to be honest, it looks nothing like the oe standard dump valve, there is only 2 pipes on it the bottom big hose goes to the intercooler and the top hose (thin one) goes to the inlet manifold, the remaining hole that the standard d/v goes to is blanked off with a bolt. this is definately a recirculating d/v isn`t it?? i thought a vta d/v has a little trumpet on it??

birtywrx

pics?

Peanuts

iTrader: (15)

no thats vta, and the cause of your woes.

the recirc valves have two big pipes, one from intercooler and one to the inlet pipe just before the turbo compressor housing, as well as a small bore pipe that plumbs ino the manifold.

988wrx

Arrh i see but have i not got my vta dump valve plumbed in correctly???

I still have to put the small hose from the d/v back to the inlet manifold where the standard small hose went?

is a recirculating dump valve a better buy then?

Brit_in_Japan

There's many a post on recirc vs VTA dumo valves. You can do a search to find them.

In short a VTA does not give any performance benefits, in fact it's more likely to harm performance by giving hesitations when it dumps. Long term harmful effects of increased wear have not been proven, but it's not going to help the longivity of the engine by running over rich mixtures through the combustion chambers when it dumps.

VTA gives you a whoosh, that's it.

Recirc is the better performance option. You can get a similar sound effect (if that's all you want) by using an induction kit.