Forge question

[Boothy]

http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=0006&product=FMFSITA

Could somebody who knows about Dump/Recirc valves have a look at this and tell me if thats the only bit I'd need or does it need something else as well? It reads like its part for a part if that makes sense?
 

[Boothy]

I forgot to ask this bit............

.......is it a REALLY bad thing to have the valve dump it atmospherically rather then recirculate it? It seems to be a bit of a mixed bag?

[iainalpine]

 Boothmeister, I remember from the days of tuning the impreza's that we used to get a sharp lean condition taking place with lift off after full boost being achieved (also known as overrun). this caused a very high flash heat in the engine and could cause engine fatigue.
I have tended to stay away from vent to atmosphere valves due to this.

Iain

[Jaywoo-GTI]

I run a fixed type on mine without any problems at all, The only thin i find is it goes off a little to often with it bein controlled electronically. Does anyone have any experience with these after a remap?

[Mark_GTIV]

Boothmeister, I remember from the days of tuning the impreza's that we used to get a sharp lean condition taking place with lift off after full boost being achieved (also known as overrun). this caused a very high flash heat in the engine and could cause engine fatigue.
I have tended to stay away from vent to atmosphere valves due to this.

Iain

Hi there, surely it would be the other way around? You would get a temporary rich mixture condition because the car would have vented to atmosphere pre-metered air that wasn't returned to the intake, so the fuel load requested would be higher than it needed to be at the moment of gear change/lift off.

Any hoo... I run a Forge instead of the Bosch diaphragm unit without the atmospheric spacer and  the 'yellow' spring on my GTI. I ran it on stage 1 software and now on stage 2 software and it works flawlessly. Certainly better than worrying about a split diaphragm all the time.

For a normal GTI 2.0 TFSI - this is all you need : http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=260303&product=FMFSITV - it comes with everything (the valve, two springs, the actuator, the vacuum lines and clamps and the remote bracket.)

If you have an ED 30 - then this is the kit you need : http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=260303&product=FMFSITVR

The part you have highlighted is to space your existing Bosch unit to vent it to atmosphere - and assuming you have a normal GTI 2.0 TFSI and that is what you want to do - then that is the correct part.

[iainalpine]

When you lift off for changing gear the car runs lean as the injectors are shut off (if your TPS) is set right. When we fitted the dump valves and were running the cars up on the rollers the lean condition seemed to be worse which was backed up with very high exhaust gas temp's. Cant explain why this happened.

Iain

[Mark_GTIV]

Hi Ian,

That sort of doesn't make sense to me. The condition you describe would surely be made *worse* when a recirculating or standard diverter valve is fitted, because there would be *more* air present.

Cars with Air Mass Meters run rich on gear changes with an atmospheric valve because they're dumping *pre-metered* air. The car has already calculated the correct mixture, has injected the fuel and is waiting for the correct amount of air to show up in the combustion chamber that never arrives for that moment, because on the gear change / lift off, that air gets dumped out the system - therefore there is more fuel than air at that moment, the air fuel calculation is temporarily incorrect with more fuel, which gets burned off or just hits the exhaust - hence the usual pop / brown smoke puff on shift - so I'm not sure what was happening with the cars you mention running lean.