Provent / catchcan fitment kits.

[Ryeman]

No, I mean when it is operating. Valve open. It's nature is recirculating.... It recirculates exhaust gas through the engine.

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Yeah, I get that, it's just the matter of why an oily atmosphere would not be kept separate from the regurgitation and, instead, allowed to foul the EGR.
It's the fact that it's claimed that the catch can helps keep the exhaust gas recirculating system absent of oil mist which should never have been the case ....or is there something obvious I've missed?

(on another forum I made the suggestion that a catch can could help keep the EGR free of oil contamination which resulted in the, in hindsight obvious, statement that the two systems were separate from each other, in that the oily mist is introduced downstream of the EGR therefore not relevant to 'it's' fouling)

Am I missing something?.

[Gigitt]

You are not missing anything. Both systems are separate and one affects the other.

The issue is not one or the other. It is the combination that together they create a sludge that stick to the inside of the EGR and intake and builds up to clog everything up.

You have to remove one or the other.

It is easy to remove the oil vapour from the PCV and also LEGAL.

Removing the EGR harder and illegal.

[gldgti]

The oil most is not introduced downstream of the egr, its upstream

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[Ryeman]

The oil most is not introduced downstream of the egr, its upstream

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What!
So the PCV directs the unfiltered blowby directly into the EGR from the upstream end.
The EGR redirects some of the exhaust plus all of the oily blowby sump fumes back to the engine through the turbo for 'reprocessing'!!??
It's difficult for me to think there isn't a better system of dealing with two different systems...sump fumes and exhaust gasses separately.
No wonder there is a 'gumming' issue of both the turbo impeller and EGR plus inlet manifold as well.

[gldgti]

Please carefully reread my answers. The egr introduces exhaust gas after the turbo. The pcv introduces crank case gasses pre turbo.

There's no gumming issue of turbo impellers. That really would be crazy.

The pcv gasses are not unfiltered on modern cars, but often there is not as much oil removed as could be with a higher capacity system (such as adding a prevent)

The aim is to prevent emission of hydrocarbons from the engine. Recycling the crank case gasses through the engine is an efficient method of dealing with that.
Recirculating exhaust gas happens only during specific circumstances, which the ECU controls ( there is an egr map just like a fuel map).


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[kaanage]

So what happens if we just let the EGR flap clog up (besides the ECU throwing a CEL)?
NOx emissions will increase but what else?

[Ryeman]

So what happens if we just let the EGR flap clog up (besides the ECU throwing a CEL)?
NOx emissions will increase but what else?

To me, who is struggling with this - I'm think the EGR contamination is strictly 'post combustion'.(?)
add
I'm a pre OBD old man and accessiblity aside and creaking joints, I'm simply not equipped to cope anymore.....they're both in warranty anyway.
BUT I'm fascinated by advances in design and tech.
Personally, I think we're in the last decade of 'reciprocating' engines and their expenses but one thing is certain, change is accelerating and there are going to be winners and losers.

[stevan]

Kaanage,If you have a diesel particulate filter it will also clog up...

[kaanage]

Surely no more quickly than if the EGR was still working.
And what if you don't have a DPF?

[Greg Roles]

Dropping EGR increases EGT's which reduces soot. EGR is the DPF's enemy. The problem is the EGR valve and the antishudder flap will stall on the gunk, burn out, and the car goes into limp, on the antishudder flap specifically, as this is important to complete DPF regens successfully. I had a hell of a time completing regens with the EGR and antishudder flap removed on my old GT TDI, and I wouldn't recommend it as user friendly! Put my car into limp many a time.....