Excessive fuel

[amber.2]

I've just replaced my battery as it wouldn't charge above 12.3 Volts , I was advised to remove the shunt off the battery to let the Alternator fully charge the battery ,now charging at 13,8 full time , last week i had to attend a funeral in Sydney from the Gold Coast to ,i now find i can only drive to Hexam , before refueling where i could reach past Hornsby before i used 223 litres for 1,900 km 8.52 litres per 100 km , any ideas

 

[Old.Tony]

I wish I could have economy as bad as 8.5LPHK!!!

Actually I checked the calc. 223 litres divided by 19 hundreds of km = 11.73LPHK. That's a little closer to mine (long haul, not towing, I'm getting about 12.3LPHK, my roof racks and basket will be making a difference, as will the fridges and tools in the tub).

Have you changed anything on the car? Tyre size, perhaps? How long since you've treated it to a nice bottle of injector cleaner? Have you changed brands of diesel recently? How long since the fuel and air filters were changed (both matter)?

 

[amber.2]

I wish I could have economy as bad as 8.5LPHK!!!

Actually I checked the calc. 223 litres divided by 19 hundreds of km = 11.73LPHK. That's a little closer to mine (long haul, not towing, I'm getting about 12.3LPHK, my roof racks and basket will be making a difference, as will the fridges and tools in the tub).

Have you changed anything on the car? Tyre size, perhaps? How long since you've treated it to a nice bottle of injector cleaner? Have you changed brands of diesel recently? How long since the fuel and air filters were changed (both matter)?

The vehicle has only done 20,000km had two full services at Nissan ,with only two people in the car and sitting on the speed limit 100/110 kph the only thing I've done is replace the battery and remove the negative Shunt ,

 

[Old.Tony]

Then I'd expect a little better than that ... how does it roll? Does it seem to lose speed faster? Possible dragging rear brakes? How hot are the front and rear wheel nuts after you've been driving (without braking a lot) and come to a stop (so, flat ground or uphill even better and stop at the top) ?

I'd pull the air filter out and check it anyway. What are the chances the dealer forgot the air filter? Have you had to drive through a significant amount of dust? Does it feel like it still has similar amounts of power or does it feel somewhat sluggish?

 

[tweak'e]

the only thing I've done is replace the battery and remove the negative Shunt ,

the negative shunt is actually a fuel economy feature so not surprised you lost some fuel economy with it disconnected.
its there so the ecu controls how the battery is charged. if battery is highly charged it saves fuel by stopping charging. afaik it can also do things like charging when coasting down hill.

 

[amber.2]

After much though i have replaced the Shunt to the Negative side of the battery ,
Thanks everybody ,

 

[DaNav]

After much though i have replaced the Shunt to the Negative side of the battery ,
Thanks everybody ,

Hi Amber, did re-installing the shunt resolve your fuel consumption problem? We're having similar consumption issues on a 2017 Nav we just bought and as it has a dual battery installed I'm wondering if the shunt has been removed, hence our 11 to 11.5 l/100 kms on an easy trip.
As the car is new to us, I'm not sure what the shunt looks like or where it is (I guess follow down the -ve battery cable) so was hoping you might be kind enough to post a photo if you get a sec?