If EGR is blanked MAF requests more air to pass through it and may throw up a fault "air mass to high". But does it on the CRD. This reading was from a 2004 BMW 530d.

 

As far as I can tell from Dr. Google, the "EGR vacuum-valve" at the front of the 2.8 diesel is a micro. controlled valve which passes vacuum power through itself via the two black plastic pipes from the inlet manifold to the pneumatic operating diaphragm on the actual EGR valve which allows or not (as be the case) some exhaust gas into the inlet manifold. In plain english, the micro. can turn the vacuum through the "EGR vacuum-valve" on or off at will. The actual EGR valve has an operating diaphragm very much like those old advance/retard diaphragms on spark-distributors for petrol engines. That diaphragm has a small piston that covers or uncovers (as be the case) a hole in its casing coming from the exhaust system, thereby allowing the inlet manifold to suck this "bled" exhaust gas into the cylinders.
So....after disconnecting the electrical actuator lead to the "EGR vacuum-valve", if I've got this right, that fact that I can't see any difference in operation, smoke etc., must mean the the vacuum is shut off, and there is no operation at all, at any time, of the actual EGR diaphragm, and hopefully, NO EGR!
Quod erat desperandum...

Leedsman.
n.b. According to Wickepedia, the treatment of petrol engines is rather different from diesel engines in the respect of EGR. It is said that there is a fall of efficiency with EGR in diesels, and that a DPF filter is needed to deal with the smoke caused by the EGR. Enough said I think...

 

Anyone interested in EGR operation generally should examine this website --
Exhaust Gas Recirculation (EGR), NOx and particulate measurement | Cambustion

Although a commercial site, a lot of accurate sense is to be found here, not the usual second-hand waffle as on other sites.
It clearly shows the EGR system in practice is quite different in application to diesel engines vs. petrol. The only caveat I would mention is the one about engine damage -- I ran diesels in the 1970s and 80s with turbochargers and NO EGRs and there was no trouble, or talk of trouble.
I was surprized to learn that in a diesel at part-power, there can be up to 50% exhaust gasses in the inlet charge of "fresh" air.
Another thing I didn't know -- these EGRs suffer from "EGR lag" esp. during gear change, but also during any alteration of the accelerator pedal position.

Leedsman.

 

I just wait for the perfect step by step guide to remove the EGR when tests show explicitly it is beneficial
*subscribes to this thread*

 

Nice one Leedsman that answers one of my doubts. Reading that EGR reduces available oxygen in cylinder, then again this deliberate reduction reduces power says it all.
On foot down EGR closes to give full power, that's good. But in all other situations the EGR is passing exhaust gas which has the oxygen burnt off in it. So with the EGR installed the engine is not producing the power it should, except in boot down of course.
So it just goes to show that blanking off EGR increases your normal running and cruising power.

 

i have a topic I stated a short time ago regarding my EGR ,it is not electronic, it works off suction , it is on the top of the manifold at the rear of the engine , I blanked mine off because it was full of crap and the pipe that runs from it down to the inlet manifold was blocked , I can't see the point in just disconnecting the feed because if the EGR is stuck open , disconnecting it will not make any difference

 

So was your engine running ok with your EGR pipes blocked and with no codes.

 

It seems to be universal that EGR is not employed either at full power or idle, as the full power would be curtailed, and the engine would rough-idle if EGR was in operation then.
Some engine designers use an excessive valve-timing overlap to get the same effect as EGR due to exhaust gasses being sucked across from one open valve to the other, but as you might imagine, this technique can't be easily controlled.
The reduction in compression ratio (down to 16:1 or even 14:1) seems to hold better possibilities than EGR, but its effects are complicated, the exact type of injector being critical. There are mixing and burning phases plus ignition delay (1 to 2 milliseconds of that order) from the burning diesel injector spray which need to be factored in. The injection timing also has to follow a different curve, mainly more retarded.
Must say I can't wait to see what effect on fuel consumption this minor mod. I've done will have. But the type of driving and territory must be the same as usual to produce credible figures.

Leedsman.

 

no mate it would hardly move off stand still at times , if I was at a junction I had to wait till I had plenty of time to pull out , but now it shoots off

 

Yesterday i just disconnected EGR vacum valve plug (front of the engine) and today replaced air filter. I can say that it worked for me...no smoke as before and seems sound and move nicer. Maybe i just see what i want to see...but i like it No check engine light or codes Yet. So if i will do some other work on engine then i will blank egr complitley. Gets done same time as camcover gasket. But thats going to be pain in ***..

My car is 2005 Chrysler Voyager Plus 2.5 crd.