EGR valve

[Kittyhawk]

Too cold and wet for the workshop so having a read about maintenance requirements on my diesel truck.
It has the compulsory EGR valve installed.
The valve is a pain in the bum to get to and needs attention now and then but that's ok, save the planet and all that.. but does it really?
Ignoring populist opinions and limiting my reading to peer reviewed research, the average EGR valve reduction in bad NoX emissions is in the realm of 50 - 60%. But there is an unspecified increase in other particulates, CO2, and smoke. Additionally, the valve accounts for a 20% increase in diesel fuel consumption. Its difficult not to conclude that the decrease in NoX emissions is offset by an increase in other nasties and also increased by burning the extra fuel that's needed to enable the valve to reduce emissions in the first place. Sounds a bit like a Catch-22.
Perhaps the only benefit is that it enables politicians to pat themselves on the back and spout off ad nauseum about all the good laws they're enacting to save us all.
Considering removing the valve unless I can be convinced of good environmental reasons not to.

 

[Noel]

If it's mechanical stick a plate on it, you'll get lots more air in and use more fuel. If it's ECU controlled then best of luck and money..........
Just clean it out.

 

[deema]

Pretend you’re back living In the 1970’s when scientists were gleefully claiming that by now we would be doomed due to climate change….they predicting an ice age! Yes, you read correctly, in the 1970’s to avoid the imminent threat of global catastrophe from the man made ice age we should have all been burning as much carbon as possible. Ironic isn’t it!
Based on the predictions of the late 80’s and 90’s we should now no longer have any ice at the poles, no snow on any mountains and all low land be flooded…..yep they flipped from ice age disaster to climate over heating…….and none of that came true either….

For me, do what ever is necessary to use the worlds resources as carefully as possible, take off the EGR if it uses more fuel. There is only so much oil after all.

 

[Kittyhawk]

If it's mechanical stick a plate on it, you'll get lots more air in and use more fuel.

This is where it gets complicated. Research indicates an EGR valve increases fuel consumption by around 20%. I can't verify that as the valve has always been fitted to the engine, but you propose that the opposite is true?

 

[JKM]

I thought increased consumption was only during starting/warm up as that's when it needs to generate heat to make the system work. I don't think it is supposed to increase consumption all the time, especially not on a run

 

[Kittyhawk]

An update.
Since Noel implied having the EGR valve installed on my truck would improve fuel consumption I went back to my reading and found a bunch of scholarly research articles confirming what he said - which is in contradiction to the bunch of scholarly research articles I read yesterday espousing the opposite viewpoint. I will hold the assumption that having the valve is on balance beneficial to the environment.
So I'm going to take the valve off, clean it out and put in back on the engine. Then I'm going to my workshop and go back to hacking into a piece of wood. I can do that all by myself without any imput from the scientific community and their 'research.'

 

[Ozi]

I'm not claiming any expertise on this, I have been told that the increase in fuel consumption is only during the warm up and under some load conditions so the overall increase depends on journey length and use you are making of potential engine power. It sounds like you have done some research, are there any good articles you could point us at?

 

[clogs]

my EGR has been blanked off for around 50,000 kilometers.....99....1.9TD, T4.
and in those years its had around 6 MOT / emission test.......
nobody has twigged about it.......
now looking for a pre 1999 Toyota Starlet D.......
even if I have to rebuild the engine it will be better/economic in the long run than all this modern Carp.......
ps rust aint a problem here.....
Still see modern D's beltching smoke.....so much for electronics.....

 

[Noel]

What model is it?

 

[Crazy Dave]

I owned a 2002 2.0L TDCi Mondo Mk3 for 16 years with the vacuum tube removed from the EGR valve and plugged with a pop rivet.
As was previously mentioned it was a mechanical/vacuum operated valve so was a simple reversal if required, but it never was needed.

EGR valve function diverts exhaust gas including any other solids left over from the combustion cycle back into the induction system whenever the throttle is closed to be burnt once it's opened again and trust me when I say this the very last thing you want going into your engine is a non-combustable gas if you're looking for fuel economy or performance.
This system is also responsible for clogging up intake valves which will eventually destroy your engine, some may argue this point but just imagine a chunk of built up carbon becoming dislodged from the intake valves and either dropping into the cylinder or worse getting trapped between the valve and valve seat.

So should you disable your EGR valve? I say definitely.

If you have an ECU controlled valve anyone with a OBDll programming tool can disable/delete it.
Search 'EGR delete' on google.

Good luck and I hope this helps you decide.

PS. Regarding emissions testing it won't be any different.

 

[ChaiLatte]

...trust me when I say this: the very last thing you want going into your engine is a non-combustable gas if you're looking for fuel economy or performance.

Does nitrogen qualify as a non-combustible gas?

 

[Agent_zed]

very last thing you want going into your engine is a non-combustable gas if you're looking for fuel economy or performance.

But the point of the EGR is to recycle unburnt particulates back into the engine to be fully burnt.

 

[Agent_zed]

Still see modern D's beltching smoke.

most probably because they have a sticking EGR valve. The vast majority of vehicles leaving black clouds that I've seen are at least 10years old and look pretty rough in general.

 

[gcusick]

most probably because they have a sticking EGR valve. The vast majority of vehicles leaving black clouds that I've seen are at least 10years old and look pretty rough in general.

And it’s probably safe to infer that other aspects of maintenance will likely have been neglected, too.

 

[MF1000]

Best liquid to clean such a valve with is methylene chloride …but wear good gloves as it will quickly degrease your skin

 

[Stevekane]

On the Saab 1.9 TD, thats a Fiat, Pergeot, Lancia and plenty of Vauxhalls a simple annealed copper plate in place of the gasket blanks off the EGR to good effect, and an apparantly great fix for fancy Variable Turbo Vanes is Mr Muscle Oven Cleaner, didnt try it on a turbo but it worked on a stuck earlier Saab EGR.

 

[moosepig]

But the point of the EGR is to recycle unburnt particulates back into the engine to be fully burnt.

Actually, no... the purpose of EGR is to reduce the amount of oxygen in the mixture thereby lowering the combustion temperature and as a result producing less NOx. The soot and other particulates that are re-introduced as a by-product are undesirable as their abrasive nature can shorten engine life.

 

[Crazy Dave]

Does nitrogen qualify as a non-combustible gas?

Yes, because the gas is Nitrogen Dioxide and is non combustible.

 

[Crazy Dave]

But the point of the EGR is to recycle unburnt particulates back into the engine to be fully burnt.

Unburned diesel is soot. You won't gain much if anything from burning it again.

 

[Fergie 307]

The whole thing started years ago. If you look at an old engine from the 60's they just had an open pipe to vent vapour from the engine crankcase directly to the atmosphere. Then they decided that should be fed back into the carb and burnt. And so we reach the stage we are at now, where the engine is used as a disposal unit for its own waste! As Crazy Dave says the benefits are a bit dubious, you may as well try and burn smoke.