Blanking off EGR

[daveparry]

Most of us are probably aware of exhaust gas recirculation but is it ONLY fitted to appease those tree hugging mother fookers, or has it got other benefits.
I ask becaused the trend i have found is to blank the bloody thin off!

Any comments one way or the other!

[pistonchris]

Well it can not be that important because vauxhall sell blanking plates for most of there range.

[McSam]

It works on the idea of lowering emissions by mixing some of the exhaust gas back into the intake air charge, so the overall percentage of harmful emissions goes down because some of them will be burnt off second time. I think.

I am, however, quite sure that it costs you some power, as your intake air is always going to be slightly contaminated by crap exhaust gas that won't burn as efficiently - read, powerfully - as pure fresh atmospheric air would.

So by all means blank it off only reason it is there is to make emissions regulations easier to meet. The car as sold new in a dealership must meet these regulations, but there's nothing to stop the manufacturer themselves offering upgrades that would then make the car not meet the regulations

[Egg Chaser]

McSam said:

It works on the idea of lowering emissions by mixing some of the exhaust gas back into the intake air charge, so the overall percentage of harmful emissions goes down because some of them will be burnt off second time. I think.

Close. It recirculates some of the exhaust gasses to reduce the combustion temperature, which in turn reduces the amount of NOx produced, which in turn keeps the tree-huggers happy.

[Busa_Rush]

The biggest problem with them is that they let all the soot and rubbish from the exhaust clog up the inlet. This not only lowers performance but makes the emissions worse and reduces engine life - it's a fantastic own goal by the environmentalists. They may work OKish when the engine is new but after just 10,000 miles they can clog up, fail to close properly, waste boost pressure, increase emissions etc

Black it off and if possible, clean the inlet manifold - your engine will run much smoother, quieter, be more economical and make the same power it ought to have done and the emissions will be lower than with a clogged up, dirty, leaking engine.

I believe they were fitted as a result of an EU directive, a political solution to a problem which didn't exist rather than an engineering solution to a genuine problem.

[dxg]

I have been led to believe that a blanked-off (or removed) EGR valve will shortly be an MOT fail, if one was present when the car left then factory.

Which is a real pisser, because all they seem to do (on the VAG PD TDI, anyway) is get gummed up (along with the inlet manifold and valve seats). I was planning on removing mine and installing a catch can, just so the engine only gets nice fresh air).

[McSam]

Egg Chaser said:

Close. It recirculates some of the exhaust gasses to reduce the combustion temperature, which in turn reduces the amount of NOx produced, which in turn keeps the tree-huggers happy.

'Course it bloody does, I knew full well that the high levels of NOx are because of combustion temperatures being far higher in diesels. As I wrote that I asked myself how re-combusting the gas could get rid of stuff that was created by the first combustion cheers!

[MC Bodge]

dxg said:

I have been led to believe that a blanked-off (or removed) EGR valve will shortly be an MOT fail, if one was present when the car left then factory.

The easiest way is to disable the actuator in the closed position, if the ECU will accept it.

[daveparry]

Looks like I am going to blank it off then eh!, thanks as ever PH people!

[wackojacko]

Exactly what has already been said.


Been meaning the blank off the EGR valve on mine for ages.

[Astra Dan]

dxg said:

I have been led to believe that a blanked-off (or removed) EGR valve will shortly be an MOT fail, if one was present when the car left then factory.

I don't see how. It's not working at idle anyway. If you blank it off with a homemade gasket without a hole the ECU won't know the difference.

[Deluded]

How would an MOT tester know? They aren't allowed to take anything apart so wouldn't be able to see the blanking plate.

Obviously emissions would go up but would it be enough to fail the test? Even then the tester couldn't put it down to a blanking plate without taking stuff apart.

[attym3]

^^^

Its not up to your MOT tester to find the reason though, he/she will just fail it.

Mark

[Busa_Rush]

attym3 said:

^^^

Its not up to your MOT tester to find the reason though, he/she will just fail it.

Mark

Some blanking plates are internal - they'd never see it and in any case, show me an MoT tester who will be bothered with the EGR valve - most of them don't even know what it is let alone what it looks like.

[Astra Dan]

Emissions don't even go up. I didn't notice anything on my MOT this year from last years in my Astra, pre and post EGR block-off.

[Flibble]

The lower combustion temps has a beneficial effect on exhaust valve lifetime though (since they don't get as hot), whether you'll notice the difference in practice is another question.

[Flibble]

Astra Dan said:

Emissions don't even go up. I didn't notice anything on my MOT this from last years in my Astra, pre and post EGR block-off.

There should be an increase in NOx in the fast idle test, however it's not tested for all petrol cars at present so it might not make any difference to MOT pass/fail.