No EGR = 10% fuel economy improvement

[Shaka1976]

Decide to disconnect the EGR on my 2.5TDi last weekend after reading about all the trouble people have had. Only pulled the pipe off and plugged it. The difference in power was immediate and after running a full tank fuel economy has improved by 10%. Got 503 miles instead of my usual 430-470. So now I'm very happy as my commute is 70 miles per day.

[kid-jensen]

Hi,

Do you have to re-connect it to get through the MOT?

Presumably, one or more emissions will be much higher now...

[gazza57]

Shaka1976,

Removing the EGR will as you say, improve the economy and performance but you will most definitely fail the MOT emissions test.
By the way, should you get pulled and checked for emissions, this does happen quite often VOSA teams have been known to set up at motorway services, you might get away with failing an emissions test because something has failed, but if it can be demonstrated that the EGR has been deliberately bypassed as you have done, it will be more difficult to justify and ignorance is no defence.
I think the penalties for commercial transport are hefty, although I'm not sure the same criteria are applied to private vehicles.


Gazza57

[Camb-Tech]

How many times do we have to go down this road!!!

Diesels, especialy this age, are not tested for emissions only smoke particles.

Read the VOSA web site and various MOT web pages and you'll see.

Only the Nox levels increase we you take the EGR out.

Best thing to do is put a grub screw in the vacuum pipe, make sure its a tight one, screw it in, then put the pipe back on.

It can be removed if needed leter on by just unscrewing the grub out.

With regards to MPG, don't forget it's about 10 degree's warmer than lately and that makes a big difference to the MPG too.

[Shaka1976]

Since disconnecting the EGR the car actually smokes less. I was thinking of reconnecting it to be 'legal' but fitting a modified gasket to limit its performance i.e. restricting the exhaust flow into the inlet manifold to say a 10mm diameter hole.

[gazza57]

How many times do we have to go down this road!!!

Diesels, especialy this age, are not tested for emissions only smoke particles.

Read the VOSA web site and various MOT web pages and you'll see.

Only the Nox levels increase we you take the EGR out.

Best thing to do is put a grub screw in the vacuum pipe, make sure its a tight one, screw it in, then put the pipe back on.

It can be removed if needed leter on by just unscrewing the grub out.

With regards to MPG, don't forget it's about 10 degree's warmer than lately and that makes a big difference to the MPG too.

Thanks for the info Camb Tech,
Remember though although you may have explained this to others a few times before, obviously not to the posters on this particular thread, so be a little patient with us eh buddy?
Gazza57

[Sparky Charlie]

You do not get better consumption figures buy removing/blocking EGR.

The whole idea of egr is to effectively run your 2.5 litre engine whilst only putting the fuel in for a 1.7 litre engine. To make this possible whilst maintaining the compression ratio they fill the cylinder with partially with inert exhaust gas and only a bit of fresh air, to which an amount of fuel is added which allows complete combustion. With out EGR the cylinders will fill up with air only. the air flow meter will see this air going into the engine and deliver the required amount of fuel.

Egr is also used to raise the combustion temperature, to keep your cat hot, to help prevent it sooting up as well as reducing the the Nox emissions.

You might have seen an increase in range but that could be any number of things. A properly maintained EGR system will allow for lower fuel consumption with a like for like driving style.

Charlie

[Camb-Tech]

You do not get better consumption figures buy removing/blocking EGR.

Thats to be argued

The whole idea of egr is to effectively run your 2.5 litre engine whilst only putting the fuel in for a 1.7 litre engine. To make this possible whilst maintaining the compression ratio they fill the cylinder with partially with inert exhaust gas and only a bit of fresh air, to which an amount of fuel is added which allows complete combustion. With out EGR the cylinders will fill up with air only. the air flow meter will see this air going into the engine and deliver the required amount of fuel.

Wrong. The main purpose is to reduce oxides of Nitrogen. You do reduce the amount of fuel going to the engine with the introduction of EG but the result is also a drop in power output. If it was all to do with injecting less fuel but keeping a specified cylinder volume then the manufacturer would just increase the charge pressure and decrease the amount of fuel injected. The problem with this is last it increases the exhaust temperature, which is BAD for turbos.

Egr is also used to raise the combustion temperature, to keep your cat hot, to help prevent it sooting up as well as reducing the the Nox emissions.

EGR is used to decrease exhaust temperatures to help increase the life of the turbo and related components. Removing EGR stops the inlet manifold coking up. I've removed the inlet off a 120K 1.9 tdi to find a 5mm extra wall of crud in the inlet. Tell me, this can't be good.

You might have seen an increase in range but that could be any number of things. A properly maintained EGR system will allow for lower fuel consumption with a like for like driving style.

Charlie

VAG do not have a scheduled maintenace plan for the EGR valve. So how would you maintain an EGR valve then?

[Camb-Tech]

Some light bed time reading for the information hungry members.

http://www.ias.ac.in/sadhana/Pdf2004Jun/Pe1131.pdf

[Shaka1976]

Just a quick update, I've manage to get 494 out of my second full tank since disconnecting the EGR. So that is 24 miles more than my previous 'with EGR' best and 44 miles more than my usual average.