dump valves

No throttle plate in a diesel, no dump valve needed, none fitted as standard. Any attempt to fit a dump valve will be a bodge, will damage performance and if persisted with will damage the engine.

mike.c1979 wrote

There are dump valves for TDi's that are activated by the ECU, such as the Forge one. Does not affect performance, purely an aural thing.

In other words, it just makes a noise I contend that it does affect performance, negatively: it is a boost leak, after all.

Problem is that the valve is over £200, the fitting kit is £110 and 2 hours labour to fit (according to Motorscope, North Yorkshire).

I'll be honest, I find the fascination with dump-valve-noises hard to understand.

Have you had a look at the fitting instructions on the Forge site?

You have to open the ECU wiring bundle. Then use a scotchlok connector to tap the throttle position signal from the ECU wiring. Lose that signal and you're into emergency limp mode - high idle speed to allow you to crawl to the nearest garage, then once the engine is switched off it won't come back until the problem is fixed.

Scotchlok = bodge. They are unreliable, and fail in spectacularly bad ways - you are basically *almost* cutting one of your ECU signal wires in half.

The instructions are coy about where the valve interferes with the boost, but it's going to cause a boost leak, resulting in fuelling spikes as the ECU tries to make sense of what's happening.

If you really must have your engine fart at you, then fit this by all means, but at least feed it from a sodastream gas bottle rather than interfere with your boost. But it's posing, all the same.


I can't blame Forge for filling a gap in the market - there's a demand, they're shifting these things.


The product description is a prime example of marketing bullshit:

Unlike mechanically derived products this kit has been created to symbiotically utilise the vehicle manufacturers latest innovations in order to allow the installation of an atmospheric dump valve to the VAG diesel engine.

Translation: This thing doesn't respond to mechanical boost pressure at all, doesn't dump excess because there isn't any in a diesel. What we do will allow you to install a dump valve - note we carefully don't say that it will do your performance any good.

Symbiotes are beneficial: this is a parasite.


Information harnessed direct from your engine management system is interpreted by the supplied Electronic Valve control Unit (VCU) in order to optimise the activation of the twin piston valve.

Translation: We tap the throttle position signal to open the valve in about the same places a petrol car would need to dump boost. Mostly.

For ease of installation we have also created vehicle specific fitting kits that utilise silicone boost hoses, which can withstand the greater temperatures and pressures associated with performance engines, along with an additional wiring harness, fixing brackets, vacuum line solenoid valve and fitting instructions.

Translation: Some of these bits are just like the bits on racing cars. Note we carefully don't say that it will do your performance any good.

alternatively puff up your cheeks as HARD as you can until you cant hold it in no longer - practice practice then time release with each gear change.

try it until you feel bored and/or silly as it is exactly the same effect original or alternative

If you realy want to have the noise there are speeker kists for about £40 on the bay with a microswitch that sits under the clutch pedal.