hey guys im buyin a dump valve for ma scoobie and just wanted to find out if this is a good move as ive heared so many storys bout aftermarket dump valves that they make the car loose power and only sound good but some people say they help the turbo etc this is the kind of DV im going to get BLITZ DD STYLE DUMP VALVE BLOW OFF VALVE BOV is this a wise move plz help cheers

 

right, i know people will tell you to search for your answer, but the general gist of it is this.

Your car comes with a recirculating dump valve as standard, this dumps the air back into the inlet and it is read by the airflow sensor and the fueling is set accordingly.

If you are planning on fitting a VTA ( vent to atmosphere ) valve ( the whooshy ones lol) then it will upset the cars fueling becasue the airflow sensor thinks more air is entering engine than really is ( because its been dumped into the atmosphere rather than being recirculated) and so the car will run rich at certain times

This will do potentially 2 things, if you have a decat it will make your car pop and bang as the excess fuel is dumped through the exhaust, if you have a cat then you will eventually damage it as they dont like being coated in fuel!
The excess fuel can creep past the piston rings ( borewash) and cause the oil to become contaminated and watered down, again not really a good thing.

Of course if you are running an after market ECU with a different airflow metering system then itl be fine as the air/fuel mix is measured differrntly

 

cheers i couldnt tell ya what ecu its runnin on all i no is that its a jap import wrx sti and uses 100ron fuel so how would i find out if its a normal ecu as the paper work that i got wi the car says that this model of impreza is modified from the production model hence thats maybe why its got tommy kiara on the body kit etc so what should i do? should i take it to subaru and speak to them?

 

i would guess that tommykaira only did body and possibly suspension aftermarket mods, and that itd be a standard STi mechanically wise, and as such would be running a standard jap ECU ( i forget the model codes, but its in the passenger footwell under the carpet and a metal plate) and it will have the standard MAF sensor and thus be suceptable to the things i mentioned earlier.

You could always take it to a dealer or a specialist and get them to have a look for you as theyd know what to look for, i dont know much about classic shape STis to i wont try and pretend to give you any advice thatd probly be wrong! lol

 

cheers mate at least uve put me in the right dirrection thanxs a lot most appriecated