Hi Andrew,
Thank you for your reply. Yes it is the 20cm long vent pipe. Prior to my Thread I was looking at it on the Vagpart website (I find this brilliant by the way, in addition to the part numbers, for understanding how parts fit together) and I misunderstood the diagram as it showed the 20cm pipe with a 'broken' line through it, suggesting it could be longer, and showing it connecting to the air filter. I always thought an EGR vent connected to the air filter box, but from your reply I now understand that on the A2 it is a small air filter attached to the end of the pipe which just 'floats' about! So I will try to buy one and fit it to see if there is any effect.
But reading other Threads prior it seems that some have purposely shut off the vent pipe which stops the EGR from working, and possibly giving better performance! Any thoughts on this yourself?
Many thanks
Peter
Hi Peter, you might be thinking about the crank case ventilation system which does typically involve a connection from the air filter. The EGR output typically enters downstream just after the throttle valve plate and so goes straight into the inlet manifold.
To stop the EGR working, typically, the exhaust feed is blocked by using a solid plate rather than a gasket (with a hole in the middle) on the exhaust manifold connection. Most EGR systems involve a pipe between the exhaust manifold and the valve so the pipe can be discarded if blocked of at the exhaust end as long as the other end at the inlet manifold is blocked off or the valve is kept in place but disabled. I have seen the exhaust side of the EGR blocked off when the feed pipe splits, rather than replace the pipe.
The 1.4 petrol engine is a bit unusual in that the exhaust feed to the EGR valve is actually a channel within the cylinder head from the exhaust port rather than an external hose. That's why there is only one pipe coming off the valve, the "input" connection is actually from the side of the engine where the valve is mounted. If you wanted to block it then that's where you would want to do it.
The EGR is there to reduce NOx emissions and improve efficiency. Disabling it would therefore negate that. It would also probably turn on your check engine warning light as the ECU would detect a fault as the EGR and therefore the engine would not be working as expected.
What it would do is prevent the induction system from getting clogged up with carbon deposits. Some people do say that it improves engine power, although for those which I have read about its normally turbocharged diesel engines. Note that the effect on petrol engines of EGR is different to diesel engines. The benefits of EGR to petrol engine efficiency doesn't apply to diesels for example where instead EGR causes increased soot and reduced power extraction from the fuel combustion.
Personally, I wouldn't block off the exhaust recirculation it as its there for a reason and I would think that it would be better to ensure that the engine is working properly which would give you the best balance of power and economy.
Cross section picture of the EGR valve. The dangly hose connects to the small port on the side:
regards
Andrew
