Why my consumption is higher now?

[koolyce]

Hi,

I have some interrogation about the consumption of my Rogue SL AWD. Since I got my car, I did around 9.4-9.6 L/100km. But now, around 4500km on my Rogue, I do 10-10.2 L/100km and I drive the same. Cruise control on the highway at 110km/h, slow start, no A/C.

My higher consumption started since my fuel reading was bad. I tought that when the break-in period is finish, the fuel consumption is lower.

Also I did 3 times a test. I full the Rogue, do 50km on the highway at 105km/h and full the Rogue again. Result, I do 10-10.2L/100km.

I'm a bit suprise about this. Any idea? It is normal?

Thanks

[crayb]

Maybe the computer was learning your driving habits?

Have you changed/ checked your air filter?

What octane fuel are you using?

Could it be temperature related ( warmer or colder temps)?

Lots and lots of factors affect fuel economy.

Ray

[koolyce]

Maybe the computer was learning your driving habits?

Have you changed/ checked your air filter?

What octane fuel are you using?

Could it be temperature related ( warmer or colder temps)?

Lots and lots of factors affect fuel economy.

Ray

I don't use the computer for the "real" statistic, I'm a bit an enthousiastic and I'm saving all my fulling information for stats.

I have not check my air filter, I only have 5000km. I always use 87, the recommand one and the temperature is mostly always the same.

I don't about an higher consumption in town or stuff like that, but getting an higher consumption by driving on the highway at 105 on the cruise control on the same highway, I'm not sur it is normal.

[philipa_240sx]

The 0.4 - 0.8 l/100km difference you are seeing is not a lot. It's less than a 7% difference.

Can you please post exactly how you are doing your calculations? There are a few things that can cause 'errors'.

- Are you filling up at the same pump at the same gas station?- Do you stop filling on the first click?- Are you driving until the tank is empty? ie. When the low fuel light comes on?- Are you driving on different roads?

As for the break in period. There is no hard and fast rule that it's 'done' at 5000km (3000mi). I would give it some more time... until 7500km (4500mi) or more.

[koolyce]

The 0.4 - 0.8 l/100km difference you are seeing is not a lot. It's less than a 7% difference.

Can you please post exactly how you are doing your calculations? There are a few things that can cause 'errors'.

- Are you filling up at the same pump at the same gas station?- Do you stop filling on the first click?- Are you driving until the tank is empty? ie. When the low fuel light comes on?- Are you driving on different roads?

As for the break in period. There is no hard and fast rule that it's 'done' at 5000km (3000mi). I would give it some more time... until 7500km (4500mi) or more.

Hi,

I don't fill always at the same pump and the same gaz station, but I filled the car always the same, I stop filling when I get the first stop from the click.

Now I can't drive until my tank is empty because Nissan need to replace my fuel sensors, so I filled after 300-400km.

When I do my test, it is always on the same road and same direction.

Actually, 1L/100km difference for highway without any reason, I found this a lot. I can understand if it is in the city or with A/C, but it is not the case.

In fact, my fuel consumption is higher since I get problem with my fuel level reading but I can't figure the relation between.

[philipa_240sx]

Hi,

I don't fill always at the same pump and the same gaz station, but I filled the car always the same, I stop filling when I get the first stop from the click.

The automatic stop on the fuel pump will vary between gas stations and pumps. This could be introducing a lot of error in your calculations. For the calculations to be somewhat accurate, you have to fill the tank to the same fuel level every time.

I would try to fill up at the same pump at the same gas station a few times and compare the readings. Even then, I fill up at the same gas station every time and I have seen up to a 1 l/100km difference between my fuel economy calculations.

1 l/100km is not a big change. Especially when you consider all the factors that affect fuel economy.

[takeshi]

I don't use the computer for the "real" statistic, I'm a bit an enthousiastic and I'm saving all my fulling information for stats.

I think he was referring to the engine computer -- not the "trip computer" in the dash. All modern cars have computers that manage the engine and changing out a sensor may require the computer to re-learn everything. Measuring performance or fuel economy while the computer re-learns may not be very meaningful.

How long ago were your sensors replaced?

[koolyce]

I think he was referring to the engine computer -- not the "trip computer" in the dash. All modern cars have computers that manage the engine and changing out a sensor may require the computer to re-learn everything. Measuring performance or fuel economy while the computer re-learns may not be very meaningful.

How long ago were your sensors replaced?

I will do it at my first oil change, it is a 2 hours job, so going there for 2 hours, and go there in a month...I prefer to wait.

[philipa_240sx]

I don't think koolyce has actually changed the fuel level sensor. It's a moot point anyway as the ECU does not use the fuel level sensor readings for engine control. Replacing them or getting 'faulty' readings should not have any impact on fuel economy.

It is true that the ECU does 'learn' as the engine wears and constantly fine tunes the air/fuel ratio. This is referred to as 'long term fuel trim'. The only way to 'reset' this fuel trim is via the Nissan CONSULT scan tool. This is something that shouldn't be done unless service is performed on the engine. ie. replacing oxygen sensors.