I bought my first Scooby yesterday! I have a recirculating valve in it I want to get a dumpvalve what is the best to buy ior should I keep what I have on it does the dumpvalve affect your engine in anyway sorry I'm a novice at this!

 

If you fit a Vent To Atmosphere (VTA) dump valve it will upset the fuelling. The reason is that the air drawn into the engine is measured by the Mass Air Flowmeter (MAF), so during driving with the OE dumpvalve the engine knows how much air has been drawn in so injects the required amount of fuel. When you fit either a dual port or a VTA dumpvalve the ECU thinks from the MAF X amount of air is drawn in and injects the correct fuel. But due to a closing of the throttle the VTA has dumped Y amount of air to atmosphere thus giving a rich mixture, this can lead to lumpy idle and poor running. On my bug I run a dual port as my NON-OE ECU runs a Manifold Air Pressure switch. To add if you are thinking of fitting an induction kit these can F up the MAF sensor unless you use a decent cold air intake system that puts the filter inside the front wing. On a newage the OE air intake system fitted with a performance airfilter is good for 400 bhp I am not sure on this regarding the Classics.

Where abouts in Scotland are you?

 

Loads of threads on this which has been going on since time has begun

General advice of the oldies
Don't get a dump valve

Lots of running problems as above and people will laugh at you for going

pppSsSttt

 

wow your knowledge is fantastic would you advise me tojust stay away from them or go for the one you have?? i have a wrx 05 ihave an apollo k and n induction kit and 3 inch cat back revoloution exhaust the guy i bought it from was in thee process of modding the car to an andy forrest remap stage one i have all the parts bar the walbro fuel pump 225/1hr http://www.andyforrestperformance.co.uk/58901.html there are two bits still to go on for the exhaust i will ask the guy what the parts are again to be sure he said i would need the remap in place as soon as parts are on or could f**k the engine!do you think i should go for it? how much would the costs be? i am from edinburgh what about yourself? thank you

 

I just asked as was up at Lossiemouth near Inverness for 4 years and knew some of the Subaru guys up there. Stick with a recir dump valve if sticking with a MAF sensor setup. Sounds like it's the de-cat bits that are yet to be fitted as you deffo need a re-map once they are done. As you are running an induction kit with a Cat back system it needs to be checked on a rolling road to ensure the induction kit is not playing silly buggers with the MAF sensor due to the turbulent airflow. That is why I commented about a CAIK system as the length of the pipework reduces the turbulence.
I am now just outside Lincoln.