The EGR system (Exhaust Gas Recirculation system)

[imported_jamesgraham]

Some guy at work recons that if you disconect the "EGR VALVE" (the one that allows exhaust gasses back into the inlet manifold)from your engine you'll get better performance and in some cases better economy.He also said that for a turbo diesel engine it helps for the longevity of the turbo by keeping all the crap soot etc, from recirculating back into the turbo.
Is this guy talking sh*te or what, and if he right were is it on my A3. 2.0TDI /ubbthreads/images/graemlins/confused.gif

 

[jungle]

can your mate explain how a turbo works without using exhaust gasses?

 

[jungle]

[ QUOTE ]
can your mate explain how a turbo works without using exhaust gasses?

[/ QUOTE ]

ignore that question! I did not know what I was talking about.

I've just spent an hour looking at how turbos work. From the diagrams I have seen, the idea of putting exhaust gases back into the manifold would be a terrible idea as they would be too hot. A normal turbo arrangement has the exhaust gases drive a turbine which sucks fresh air into the manifold. As the air is under pressure, it rises in temperature and needs to be cooled (intercooler) before going to the manifold. Mixing in even hotter exhaust gases would appear to be a silly idea - do you know more about this EGR system?

 

[Davidwynne]

Trex,

Not a good idea as it will cause issues with the intake gas temperature and emissions.

The following link will give you a short overview:

http://www.delphi.com/pdf/commercial/ElecDieselExhaust.pdf

 

[imported_jamesgraham]

Motorcar Glossary - EGR system
The EGR system (Exhaust Gas Recirculation system) is designed to reduce emissions. To be precise, it lowers the amount of nitrogen oxide (NO) in the exhaust emissions. Nitrogen oxide is formed at very high combustion temperatures. What the EGR system actually does is direct part of the exhaust gases back into the intake manifold, which in turn helps reduce the combustion temperature and consequently lower the amount of NO in the exhaust gases. The EGR flow is controlled by the engine computer which opens or closes the EGR valve depending on the operating conditions. One of the most common problems related to EGR is the intake passage or the EGR valve getting clogged with carbon deposits causing restrictions to the EGR gas flow. This turns the "check engine" light on and sets the code PO401 - insufficient EGR flow (this is a common problem for the Acura / Honda V6 engine, for example). This problem happens mostly if a car makes only short trips so it can't warm up fully, or when the oil is not changed regularly.
st found this ,

 

[imported_jamesgraham]

It looks like its mainly to do with the emissions.So if its disconnected do you think it will make any difference to performance ,economy etc?
Can't find anything about it related specifically to AUDI A3 though.

 

[jungle]

Interesting stuff trex - and I can't make any sense of it at all!

It sounds like your mate may have been right after all. However, as you say, it seems to be related to emmisions and may only be an issue for whoever owns your car in 10 years' time, so no worries.

 

[dummi]

hot gas into the intake will undoubtedly give you pinking missfiring like running on really high boost not a good idea. if you want to rid of the carbon deposists get a decarbonising spray from halfords and spray that into the intake, if you want to go faster get a chip and if you want to get more economy get lighter shoes

that is if it diverts gas back into the inlet, probably like on old systems my passat had a hot air tube from the the exhaust manifold, not actual exhaust gas just warm air for winter running.

that covers concequences with actual hot gas in there. but i don't know exactly what EGR is about. is it like a wastegate

 

[LUGGY]

As far as i am aware in a petrol engine anyway the egr valve diverts a small amount of exhaust gas back through the inlet manifold on overrun to reduce emmisions only!
when an egr valva goes faulty it will weaken of the mixture all the time and cause running problems(will not afect a diesel in this way!)
i can see no reason why disconecting it should give you anymore power!
ignore your mate and leave it alone!
i agree with dummi get a chip!!

 

[SouthPassat]

Hi Guys

Just wanted to find out how difficult it is to replace the EGR on a 2003 1.8T?

Thanks