It has become obvious that disabling the EGR system on my GV has almost stopped the heavy fuel consumption during the warmup period. There is a slight improvement in normal temperature fuel consumption. I think there will be less clogging of injectors with higher combustion temperatures as time wears on.

For the time it took to disable EGR (i.e. disconnecting the electrical drive to the vacuum valve at front of the 2.8 diesel engine controlling EGR), this has been the most cost-effective and easy fuel consumption improvement I've ever done. The second was blowing up the front tyres to 42PSI.

I can't say there have been any side-effects on EGR disabling, or any handling deficiencies with front tyres at 42PSI.

Leedsman.

 

A long time disciple of both thanks for the tests and the objective outcome[s]. I had no idea that the mere 'disconnecting the electrical drive to the vacuum valve at front of the 2.8 diesel engine controlling EGR' would without a physical blank plate work. Showing a photo pointing to the disconnect you used would be helpful my Yorkshire friend. Congratulations on more MPG.

 

Another pointer to the effect of EGR disabling:--
I filled up at my favorite station today, and the mpg meter is now acting like it did when I got the vehicle at first, some 2 years ago.
Upon zero-ing the mpg meter after filling to brim, driving away showed the big change of mpg as between going on the level and going down a slight decline, foot off pedal. Under this over-run condition, the meter's reading went up in value quite smartly, before EGR disablement it was VERY sluggish to move up.
I'd hazard a guess from the way the performance is changing that carbon is being burnt off the injectors by hotter combustion.
I'll try to get a picture of EGR vacuum valve to the forum asap., I've allsorts on my plate ATM, inc. an oil change I've just done with Comma allegedly full synthetic 5W30 at £20:00 for 5litre. Actually, the vacuum valve you can't miss really, its right in front of you as you look at the engine (with plastic cover removed). It has two black plastic pipes to it, say around quarter inch dia. one thicker than the other.The plug is only 2-pin.

Leedsman.

 

Would same poceedure work on 2001 CRD

 

I don't know what engine you have or its EGR system if fitted. If you have a electrically operated vacuum EGR valve, it's very likely to have the same effect from disablement as mine. No doubt someone here can elucidate if your partic. EGR system if fitted is the same as CRD 2.8 diesel. I've seen lots of diagrams when I do a Google.
I think I should point out that if you have a faulty/stuck/oiled up EGR physical valve (not the vacuum valve under micro. control I've been dealing with), disconnecting said vacuum valve will have no effect, as the physical valve is likely to be stuck open. Therefore there is no control, therefore unplugging/disconnecting the vacuum valve can't do anything. If your EGR physical valve is malfunctioning due to carbon, oil, dirt foulup, you'll have to fix it first. It means the EGR is in operation when it shouldn't be, i.e. during idling and full power. The EGR should only work at modest engine power, as vacuum is measured measured by the micro., the micro thus controlling the EGR action with the vacuum valve. Put simply, moderate manifold depression brings EGR into operation. Strong depression (=idle) or actual pressure from the turbocharger (=full power) does not.

Leedsman.

 

I'm still not clear as too EGR condition without the vacuum. As a few months ago someone on here said the EGR is open when engine dead and no vacuum to it. So I take it Vacuum closes the valve as in power conditions.
So on isolating the Vacuum valve by disconnecting the power, does that let the vacuum pass through it permanently to close the EGR.
You will see here this is to be clear as someone's pipework and EGR maybe blocked giving us a false answer.
There's probably a schematic somewhere to clarify the operation.

 

Leedsman did you manage to get us a couple of pics for this mod. Thanks in advance mate

 

Here's a picture of the vacuum valve. Do bear in mind this is the 2.8 diesel, it may be different in others.

Leedsman.

 

Here are the particulate figures for my diesel GV. I assume the figures express parts per million. They were produced by a "Boston" smoke opacity analyser.

1)June 2014: 0.56.
2)June 2015: 0.39. (after disabling EGR operation).

Leedsman.

 

Thanks
I will try it this weekend, if its similar i will be very chuffed