Author Topic: Reduced mpg since dpf clean  (Read 3498 times)

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Offline Matcan77

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Reduced mpg since dpf clean
« on: December 30, 2019, 07:58:45 pm »
Does anyone know why my mpg has significantly reduced over the last year since a dpf clean please?
I drive 15,000 miles a year with mixture of urban and motorway driving was averaging 56mpg.
I have had a service including oil change, oil filter, air filter and fuel filter but now can't get above 47mpg average even on a longer run.
I've got a mazda 6 2.2 diesel 2010

Offline apav

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Re: Reduced mpg since dpf clean
« Reply #1 on: January 01, 2020, 03:19:59 pm »
What do you mean DPF clean? Did you have the thing removed and done things to it?

Do you measure the mpgs on paper or based on the trip computer?

If you are based on the trip computer, do you reset every so often or do you let it run its statistics over many thousands of miles?

Check the brakes for binding as well but it all seems that the source of your problems is that DPF clean as it all started since then.

Offline Matcan77

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  • Engine: 2.2L
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  • Year: 2010
Re: Reduced mpg since dpf clean
« Reply #2 on: January 01, 2020, 09:19:22 pm »
The light was flashing for dpf regeneration but it wouldn't do it running at high revs. The garage I took it to said they had to 'clean' it as it wouldn't regen.
The mpg was based on what the car computer was saying. I noticed the difference in mpg because I reset the trip computer and the average speed and average mpg every other week when I filled up with fuel. This was virtually a full tank each time.
The brakes are fine.

Offline apav

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Re: Reduced mpg since dpf clean
« Reply #3 on: January 02, 2020, 04:17:37 pm »
It may be OK if your only source is the reset trip computer information. The garage may have done a forced regeneration which is something you can do as well.

https://www.youtube.com/watch?v=HAYyEU4lAiw

But it is a bit brutal for the car and the more you do of them, the more you cut the life of the thing.

Just keep in mind that your car has a timing chain which is problematic. A DPF flashing light can mean that the chain has stretched so much that it needs replacement. In the worst case scenarios, these cars were going multiple chains while a timing belt car only need one. And changing the chain is not an easy job.

You will not get any noise warnings from the chain. But you can download a forscan app and keep a diary of the readings.