Sudden drop in fuel economy

[maprice]

Hi,

I have a 2017 150 DSG camper with 42k. It has normally returned mid 30’s mpg according to the MFD. Recently this has dropped to low 20s. I have serviced it and changed disks and pads front and back but this has still not improved the MPG. I don’t do short journeys and the DPF light has never come on.

Any ideas what may be causing the drop in economy, and what should I check next.

Many thanks

Mark

 

[Loz]

Have you changed the display from average to single trip? (1 or 2) in the display?

 

[maprice]

Have you changed the display from average to single trip? (1 or 2) in the display?

Yes, I have changed this. It did start happening after a Cambelt change and service. Is it possible the timing is one tooth out or would this have caused catastrophic damage?

 

[Loz]

Is it possible the timing is one tooth out or would this have caused catastrophic damage?

Unlikely, you would know.
More likely the ecu had the software upgrade for the adblue usage and may have changed fuel consumption, or more likely you are having a spell of incomplete regens, and it is regenerating every time you drive.

 

[Lukavell]

I have had this in a golf, it was a brake caliper seizing, however it was pretty obvious when I got out to have a look because not only could I feel the heat, it was creating a haze around said caliper; luckily it happened whilst diverted from the M1 and right outside an empty mechanic shop! Unlikely to be that but it could be sticking a little bit? Might be worth a quick check for excess heat after a few miles of driving.

 

[maprice]

Hi,

I have a 2017 150 DSG camper with 42k. It has normally returned mid 30’s mpg according to the MFD. Recently this has dropped to low 20s. I have serviced it and changed disks and pads front and back but this has still not improved the MPG. I don’t do short journeys and the DPF light has never come on.

Any ideas what may be causing the drop in economy, and what should I check next.

Many thanks

Mark

Hi All,

I have still not managed to find the problem. I’ve had it on a diagnostics tool and the picture below shows the results. The coolant radiator output measurement looks odd. I have changed the sensor but still no change. Can any one offer any more advice on the readings?

 

[airhoguk]

Your fuel temperature is also very odd, perhaps related to your economy issue?

 

[maprice]

Your fuel temperature is also very odd, perhaps related to your economy issue?

Yes, but not sure what could cause them to both be so out. Any ideas?

 

[Sackmycook]

Does the T6 have an actual thermostat?

Mrs SMC had her Fiestas' stuck open resulting in poorer fuel economy. Only realised in winter when we got little cab heat

 

[mmi]

The coolant radiator output measurement looks odd. I have changed the sensor but still no change. Can any one offer any more advice on the readings?

I'm afraid the diagnostics tool is reading wrong channel - probably just ignoring engine's sensor installation list.
I have seen the same happening several times - at best reading alternates between actual value and value when sensor circuit is "open".

Below a snippet from T6/T6.1 EU6 engines:

IDE10225-MAS09658	Install. list for temperature sensors bank 1-Coolant temp. sensor dwnstrm. of radiator	supported
IDE10225-MAS09672	Install. list for temperature sensors bank 1-Coolant temp. sensor dwnstrm. of radiator (SENT)	Not supported

 

[AussieMick]

Have you tried simple things like replacing the engine air filter.

 

[Stof75]

@maprice DId you ever get to the bottom of your MPG problem? I've had exactly the same symptoms recently.

 

[Aron]

Following

 

[skoti]

Same problem with T6.1.
Following with interest.