My MPG has plummeted after blanking the EGR. Its normally around 32 MPG on local Cornish B roads. However I blanked the EGR a few weeks back to identify where my coolant is going.
The MPG has subsequently dropped to 26, which is a massive drop.
 2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.

how do you explain blanking the egr causing such a drop in mpg ? ive no idea hence the question. Jules

My (historic) understanding of diesel engines is that you put a measured amount of diesel into the (unmeasured) air sucked into the cylinder and squeezed it until it went bang.
And (again historically) the main problem was putting in too much fuel during acceleration.

Now we have got complicated and engines have minutely timed and measured bits of fuel being sent into a heavily measured amount of air.

To make matters worse we have a filter in the exhaust so that you can't see the black smoke anymore to warn you that you are wasting fuel.

This most likely now means that changes to input/output track to cylinder, or errors in the sensors (or their system) could lead to changes to the efficiency of the engine (mpg).

The world is getting just too complicated! FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 76k+ miles) (MY2015)

Last edited by IanMetro on 17th Feb 2023 10:52 am. Edited 2 times in total

I'm interested in the outcome of this, I've got a 2011 HSE , I've had just over a year now and my mpg, according to the incar trip, has always hovered around about the mid twenty's . Its never bothered me in the past but now I read about other peoples mpg I'm beginning to wonder . Other than the mpg it runs like a dream, I've done all the belts and water pump, and changed all the filters. I think I'm just going to have to put up with it. It also just passed the mot with no advisers. Not sure if thats spelt right...mike

It’ll be interesting to see what’s going on. My 2011 TD4 manual got low 30s on the exact same daily drive. I expect a little lower on an auto SD4 but not this low. After resetting the trips my average mpg on the trip is 18.4mpg.

I’m getting the auto box flushed, Haldex and PTU serviced so I’ll get them to check it out while it’s in. Learned to drive in 2011.
Bought a Micra - great little car
"Upgraded" to Kia Sportage - hated it
Proper upgrade to FL2 TD4 GS 60 reg Facelift - tailgate paint issues, fuel gauge rewire, transfer box failure at 36k miles, clutch at 60k
Reconditioned diff at 70k ish
Sold at 84k and now on a DS. Terribly unreliable.
Sold DS for a 2021 Mitsubishi Outlander PHEV. Fingers crossed....
Sold Outlander for a 2014 SD4 SE Tech because I’m mental

IanMetro wrote:

For the record - I have just looked at my trip readings.

MY15 Metro SD4 Auto 66k miles

Trip B (running for my 50k mile ownership)
Ave Speed 29mph Ave Fuel 33.3mpg

Trip A (set at current refuel)
Miles run 316miles Dist to Empty 161miles Ave Speed 32mph Ave Fuel 34.4mpg (range 477 miles??)

I live in a small town, near motorway, and main use is for day trips. So mixture is motorway, cross country rural A & B roads, very little short journey town use. Car load normally quite high with 2 people, and at least one disability scooter.

Happy to be corrected (usually am ) but think the distance to empty figure when you fill to the top will be based upon most recent mpg rather than previous tank averages. Hence the disparity between your figures of 477 and 417

No, this time you are correct. After some driving around some glorious roads in Scotland I’ve seen over 600 miles as a predicted range. Never actually achieved it though!

Sidthecat wrote:

Happy to be corrected (usually am ) but think the distance to empty figure when you fill to the top will be based upon most recent mpg rather than previous tank averages. Hence the disparity between your figures of 477 and 417

Chuckalicious wrote:

Ok, safe to say something is going on.

No error codes using Torque Pro on my tablet.

The current journeys are only a couple of miles each way from cold. I’m aware it isn’t ideal but was never an issue with the previous one. It gets the odd long run to look after the dpf.

No signs of leaks or damage under bonnet. Will check the air filter this weekend. Learned to drive in 2011.
Bought a Micra - great little car
"Upgraded" to Kia Sportage - hated it
Proper upgrade to FL2 TD4 GS 60 reg Facelift - tailgate paint issues, fuel gauge rewire, transfer box failure at 36k miles, clutch at 60k
Reconditioned diff at 70k ish
Sold at 84k and now on a DS. Terribly unreliable.
Sold DS for a 2021 Mitsubishi Outlander PHEV. Fingers crossed....
Sold Outlander for a 2014 SD4 SE Tech because I’m mental

Does your FL2 start easily AND run evenly from cold. I just wondered if you are wasting fuel by injecting it into a cylinder that is not warm enough to ignite. (Maybe Glow Plug?, or Lack of Compression?, Head Gasket?),
(similar to what happens in a petrol engine missing a spark)

I thought of this as you are doing so few miles and engine not warming up. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 76k+ miles) (MY2015)

Starts and runs spot on. Learned to drive in 2011.
Bought a Micra - great little car
"Upgraded" to Kia Sportage - hated it
Proper upgrade to FL2 TD4 GS 60 reg Facelift - tailgate paint issues, fuel gauge rewire, transfer box failure at 36k miles, clutch at 60k
Reconditioned diff at 70k ish
Sold at 84k and now on a DS. Terribly unreliable.
Sold DS for a 2021 Mitsubishi Outlander PHEV. Fingers crossed....
Sold Outlander for a 2014 SD4 SE Tech because I’m mental

Trip Computer Obsession Part ???

Yesterday's journey back from refuelling gave the following reading;

Miles Run 1.1 Ave Fuel 22.4mpg From warm start



As I had a short journey into town this morning, I reset my trip

Miles Run 1.9 Ave Fuel 18.3mpg From a cold overnight start 10C, through town light traffic.

Then after 30 mins carried on (without reset)

Miles Run 4.7 Ave Fuel 23.9mpg From warmish start, around ring road at 30mph cruise (Inst Fuel 49mpg)

As you can see I only achieved 18mpg from cold on 2 mile journey.

PS for those worried about my sudden obsession, I will look out for Trip Computer Anonymous meetings locally. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 76k+ miles) (MY2015)

Quote:

PS for those worried about my sudden obsession, I will look out for Trip Computer Anonymous meetings locally