Disconnecting EGR system on 1.9TD

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nick
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Disconnecting EGR system on 1.9TD

Postby nick » Wed Aug 07, 2002 1:39 am

For a while I've been considering disconnecting the exhaust gas recirculation system on my '97 Xantia TD, particularly with the recent discussion on whether this contributes to premature engine failure.
In any case, I got the impression all this system actually achieves on older high mileage engines is to block up the inlet manifold with black gunge!, which must surely make the exhaust emissions worse in the long term anyway?
Is it just a matter of removing the vacuum pipe from the valve situated on the exhaust manifold ? When I have tried this in the past it makes the engine idle faster, but I presume this can be cured just by reducing the idle speed on the injector pump to compensate ?
Anyone here done this on a Pug/Cit diesel ? Is it likely to give any improvement in performance of fuel consumption ?
Regards,
Nick
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nick
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Postby nick » Wed Aug 07, 2002 1:44 am

PS Last line should say 'performance OR fuel consumption'!
Nick
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Dave Burns
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Postby Dave Burns » Wed Aug 07, 2002 3:49 am

EGR is a legal requirement on car's built after a certain date, and its actually unlawful to run on the public highway with it disconnected.
I don't know if the performance benefit will be that much better, the reason being back pressure, this is required to get the exhaust pressure above intake pressure at full boost, and in my opinion is where the real performance hit comes from compared to older cars without it.
Exhaust Gas Recirculation is done to keep the combustion temperature below the point at which oxygen and nitrogen react to form Nox, nitrus oxides.
I have also read that cooling the combustion temperature causes larger soot particles to form which makes them a bit less dangerous to breath in, not nice but something we can't avoid, so be warned, no EGR might just nobble your health, not much good having a car that goes better when your'e dead.<img src=icon_smile_dead.gif border=0 align=middle>
Dave
p.s. Use the edit function to change or correct a post <img src=icon_smile_big.gif border=0 align=middle>
Edited by - Dave Burns on 06 Aug 2002 22:52:05
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nick
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Postby nick » Wed Aug 07, 2002 4:31 am

Thanks Dave, I didn't realise it was actually a legal requirement.
Certainly my '97 Xantia TD is far less noticeably smokey on acceleration than the '95 TD model my dad owned a few years ago, though I'm not sure how much of this is due to egr, particulate trap, or the ecu control ?
His would often struggle to get through the MOT emissions test, whereas mine has always passed it very easily despite having covered a similar mileage, same maintenance schedule, similar style of driving etc.
Nick
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NiSk
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Postby NiSk » Wed Aug 07, 2002 1:29 pm

Hi Nick!
Buy a copy of DIESEL CAR - there's always a discusion going on there about the merits of disconnecting EGR's. Most say that it definately improves both performace and reduces consumption - but as Dave says - it was put there for a purpose!
//NiSk
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Richard Gallagher
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Postby Richard Gallagher » Thu Aug 08, 2002 3:17 am

I removed the EGR on my 97 Xantia several years ago by removing the vacum pipe from the valve next to the LHM reservoir. Basically it is easier to get to at this end. I also ditched the catalyst exhaust for a standard item. This made a difference to the performance, as the catalyst is really a form of blockage to the exhaust gases. After running a 95TD the 97 felt really flat, after doing the above the performance felt very similar. The cat would also account for the later cars producing 2BHP less. Since doing this the car has passed two MOT emission tests without problems. The test only measures smoke, not NOX. Therefore whilst it is anti-social, you will use less fuel and gain performance. Also should the exhaust need changing it will be significantly cheaper!
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