S-Type diesel in mpg shock
Discussion
Setting off yesterday to make a 65 mile journey home, making 'average' B-road progress around 50mph, I looked at the instant mpg readout and it said 95. Now this can happen when you take your foot off the gas, but it wasn't. The road was level and I was maintaining speed. After a while there was a roundabout which I thought would kill the magic, but even when accelerating gently on the other side the mpg only dropped to 50mpg - then recovered to 90+.
I reset the trip computer to see how long it would last and whether the various readings tallied. I was thinking that either the sensor had failed, or half a bank of cylinders had packed up - but the car was behaving normally.
Sadly after about 5 miles the mpg started to drop to more normal levels and I got home having averaged 46mpg - still more than the 40 I usually get.
Could this have been caused by the DPF regenerating or - what else?
I reset the trip computer to see how long it would last and whether the various readings tallied. I was thinking that either the sensor had failed, or half a bank of cylinders had packed up - but the car was behaving normally.
Sadly after about 5 miles the mpg started to drop to more normal levels and I got home having averaged 46mpg - still more than the 40 I usually get.
Could this have been caused by the DPF regenerating or - what else?
There are two DPF cycles: passive and active.
On passive cycle the DPF will require the car to regularly be driven significant distances at 2,000rpm plus for the DPF to get hot enough to regenerate and burn off the particulates in it.
Some DPFs have an 'active' cycle where additional fuel is injected into the combustion chambers to create hotter than normal exhaust gases to burn off particulates in the DPF.
On passive cycle the DPF will require the car to regularly be driven significant distances at 2,000rpm plus for the DPF to get hot enough to regenerate and burn off the particulates in it.
Some DPFs have an 'active' cycle where additional fuel is injected into the combustion chambers to create hotter than normal exhaust gases to burn off particulates in the DPF.
Edited by diesel piston on Sunday 17th April 07:43
diesel piston said:
On passive cycle the DPF will require the car to regularly be driven significant distances at 2,000rpm plus for the DPF to get hot enough to regenerate and burn off the particulates in it.
Some DPFs have an 'active' cycle where additional fuel is injected into the combustion chambers to create hotter than normal exhaust gases to burn off particulates in the DPF.
Thanks DP, so it seems to be like an oven doing a pyrolytic cleaning cycle and burning carbon to CO2 and water.Some DPFs have an 'active' cycle where additional fuel is injected into the combustion chambers to create hotter than normal exhaust gases to burn off particulates in the DPF.
Right, so 'Passive' doesn't use extra fuel so should have no effect on mpg; 'Active' usues extra fuel so should decrease mpg. Neither tallies with 95+ mpg so I think I will have to file this under 'interesting' and move on
The engine is a joint Ford/Peugeot design and uses the expensive ELOYS fluid to raise exhaust temperature during regeneration of the particulate filter...it is a similar system to that used on my Citroen C5 2.2HDi. Injecting the ELOYS would provide you with the higher than expected MPG figure...
Toffer said:
The engine is a joint Ford/Peugeot design and uses the expensive ELOYS fluid to raise exhaust temperature during regeneration of the particulate filter...it is a similar system to that used on my Citroen C5 2.2HDi. Injecting the ELOYS would provide you with the higher than expected MPG figure...
Your wrong, the 2.7d/3.0d don`t use the ELOYS system.Edited by diesel piston on Saturday 10th September 16:53
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