Just to see if disconnecting the EGR valve electrically by simply unplugging the two wire lead will make any difference to fuel consumption: It already seems from the computer read-out that there IS a difference, but it has to be proved by the brim-brim method to be sure-proven.

There is NO difference in starting or driving.
There are no tell-tales lit.
There is no black smoke on hard acceleration, or any visible smoke at all.

NB.
Disconnecting the plug can be difficult. As with most of these type of plugs, it's a "captive" one, so you have to release the plastic gripper first before the plug will release from the socket.

Leedsman.

 

I wouldn't have expected to see starting / driving / tell-tales lit / black smoke on hard acceleration / or any visible smoke at all on an already healthy vehicle - like your findings I would have expected to see a sleight but measurable MPG improvement - however I would expect the additional blanking of the EGR should throw additional torque benefits from the acceleration curve. Conversely for those unfortunates with existing :

- black smoke
- poor MPG
- flat spots
- inflexible RPM

They should expect to see some or all of the of the black smoke / poor MPG / flat spots / inflexible RPM reduced or removed. The major findings of your 'pull the electrics only' 'no blank' experiment for me was that the EMS [and its associated sensors] did not fart when the electrical connection was isolated. The quickie experiment here and the full blanking is I expect going to be 'different strokes' for different models and different lifestyles. Example, your already good engine behaviour compared to others already bad engine behaviour and school run and low RPM style driving use compared to motorway RPM. Good analyses Leedsman, particularly on the reassuring. previously unknown to me fact that pulling the electrics only had no adverse affects.

 

To clarify, do all the CRD's have electronic EGR's or just later ones. So far I've heard on here just lately, an early Crd had EGR down back of engine and the operating solenoid was round front of engine.
And Leedsman from your words I take it disconnecting wires at EGR is to close the valve. Or are these wires the positioning of the EGR valve for the ECU.

 

I know not exactly whether the micro. via this plug is reading something or driving something. This is my "suck it and see" methodology, or 'empirical approach' to use the two dollar words. As they used to say, we shall see what we shall see. Takes time.
Anyone who knows for sure what's going on here do as Goggs says and report in please. My GV is 2006, 2.8CRD.

Leedsman.

 

Later CRD's (all 2.8's I think) also have a throttle valve round the front. This closes to restrict the path from the air filter and ensure more junk is drawn through the EGR valve.

Regards
Richard

 

There is a very thin flexible pipe to the EGR valve, prob from inlet manifold, -- I'm assuming that minimum inlet vacuum plus turbo derived pressure will result in the valve allowing more EGR, ie., max power, max EGR?

Leedsman.

 

You asked that in another thread my mate, I think its difficult for anyone to know .. .. there's no central reliable dBase on the UK net as far a I'm aware and whilst the Americans can get instant 'at the time of manufacture' info with a VIN number it doesn't work for us because diesels don't exist on any American system. In this other thread I listed just some of the many many variations of EGR on both model and brand. Have a read through the workshop manuals - relevant to your engine & year type, or maybe tfb knows. Best of luck.


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The EGR should not operate at max power/idle & starting. Only at normal driving conditions. The particular EGR on the 2.8 is vacuum operated with the electrical connector previously mentioned operating a solenoid controlled by the ECM.

 

Thanks royal100805 !

- example - I'm 2.8 / 2005 - you are 2.8 2007
- no idea what goggsy & Leedsman [and most CRD owners on this forum] are they have .. .. no sig line

Does that apply to the 2.5 ? even then we have no idea what year his 2.5 might be !

 

So acc. to Royal, there is no EGR at full power etc., but exhaust gas IS fed into the inlet manifold when the power demand is moderate and therefore some vacuum in the manifold. So, stopping the solenoid by disconnecting its switch will stop EGR from being passed into the manifold, if my logic is correct...

Leedsman.