I-CTDI EGR valve. Functional operation.

[ebod]

Hi,

I know the principle that the EGR opens up a channel from the exhaust and feeds it to the inlet. And that its arguably the most useless lump ever designed ( apart from DPFs )

But I just wanted to know when the EGR comes into play in the operational range of the engine. Is it at running temp above a certain rpm....or is it at idle???

Just wondering if its the reason why my irratic idle/stalling has started to re-appear again....

 

[F6HAD]

It's not as simple as that, and when you study the maps you'll see there are various factors that come into play when the maps request opening and closing of the EGR valve.

 

[Dan Robinson]

Interestingly - the OBD allows you to see when the EGR is in operation... at least you can on my tranny...

 

[ebod]

It's not as simple as that, and when you study the maps you'll see there are various factors that come into play when the maps request opening and closing of the EGR valve.

But there must be some kind of pattern / zone which it operates in... It can't be random.

 

[F6HAD]

Combination of engine temps, emissions control values, load calculations and fuelling. Too much for me to understand myself, never mind explain it.

 

[RobB]

This article explains the basic operation of an EGR

http://www.howstuffinmycarworks.com/EGR_valve.html

 

[ebod]

This article explains the basic operation of an EGR

http://www.howstuffinmycarworks.com/EGR_valve.html

wowsers!! info overload. Very interesting though.

Just wanted to know if a faulty EGR can cause irratic hicups at idle and occasional stalling when braking.

 

[luckypedro79]

wowsers!! info overload. Very interesting though.

Just wanted to know if a faulty EGR can cause irratic hicups at idle and occasional stalling when braking.

I am prepared to be corrected here but....I think that the EGR is vacuum operated and therefore stalling under braking would indicate to me that the vacuum pressure could be droppoing thus causing the EGR to open fully and starve the engine of fresh air? This is a total guess but could be an avenue for further enquiry...?

 

[ebod]

I am prepared to be corrected here but....I think that the EGR is vacuum operated and therefore stalling under braking would indicate to me that the vacuum pressure could be droppoing thus causing the EGR to open fully and starve the engine of fresh air? This is a total guess but could be an avenue for further enquiry...?

My understanding was the pre-facelift EGR was electomagnetic. But equally I'm open to correction too

 

[luckypedro79]

Not sure on that but think there is still vacuum function in the egr. Is it not electromagnetic valve accuated on a vacuum valve?

 

[ebod]

Not sure on that but think there is still vacuum function in the egr. Is it not electromagnetic valve accuated on a vacuum valve?

Maybe post facelift.....but I'm sure pre-facelift isn't

 

[Paul the Bobby]

Pre facelift is purely electronic. I've played with one off my old car to check its activation. Post facelift is vacuum.