Diesel Increasing Fuel Consumption

[Quint]

Hi, 

2009 2.0 TDCi was averaging about 8.2-10kml/100km (very heavy traffic) for years. As I'm not using this vehicle often, but I started driving it again 2 weeks back and noticed that in the past 2 weeks the consumption has gone up to 11-14kml/100km. I find that too high for a diesel given the same traffic circumstances. So far, I've cleaned the MAF sensor, replaced the air cleaner, put injection cleaner on the car, and have observed little difference as to performance. The last oil that was used was 15w40 (hot temps here), and I'm unsure whether the heaviness of the oil contributes to the drastic change in consumption too. The car has not been driven hard at all (for years) and may need a lot of highway / high rev exposure so I've been doing this of late. The car has 113k kms on it, and would want to know if there's anything else I need to service at this point so that I could bring it back to its former performance i.e. clean EGR, etc.

Any advise on what to look out for would be appreciated. Thanks!

[drsdriver]

I would say , definitely a fuel filter change . Can make a big difference to your mpg if the fuel filter clogged. 

Also check tyre pressures . At least 34psi all round . 

[mjt]

Check the brakes are not binding. I had a sudden drop in mpg and it turned out one of the front caliper pistons was sticking.

[andypsp]

7 hours ago, Quint said:

The last oil that was used was 15w40

isn`t the oil supposed to be 5w30 ?

[Ryan_Tango]

20 hours ago, andypsp said:

isn`t the oil supposed to be 5w30 ?

He's better off using 40 instead of 30 due to the hotter temperatures where he lives. So to prevent the oil being too thin when his car gets up to temperature he must use 15w-40 as 5w-30 is too thin at normal operating temperatures in his climate.

[madmole]

15W will be far to thick when cold to provide much protection unless he lives in the Sahara. I'd go 10W-40 at most if he needs the 40 in the summer

Fuel filter would be my guess

 

 

[Quint]

On 3/3/2017 at 2:26 PM, Quint said:

On 3/3/2017 at 3:38 PM, drsdriver said:

I would say , definitely a fuel filter change . Can make a big difference to your mpg if the fuel filter clogged. 

Also check tyre pressures . At least 34psi all round . 

I do have 34psi all around. I'm due for a filter change in the next 2k kms. Thanks!

 

 

[Quint]

On 3/3/2017 at 6:13 PM, mjt said:

The average temp from where I am is around 30+ deg. The coldest temp on an average day is in the 20s.  the bumper-to-bumper traffic daily, outside temp goes up to 40 as shown in the dash. Engine temp reading reaches almost 1/2 on the indicator with A/C always on. Stop and go traffic where my speed averages 13-18kmh as indicated on the on-board computer. That is why I use 15w40. I think that 5w30 will be too thin. 

[mjt]

4 minutes ago, Quint said:

On 03/03/2017 at 10:13 AM, mjt said:

The average temp from where I am is around 30+ deg. The coldest temp on an average day is in the 20s.  the bumper-to-bumper traffic daily, outside temp goes up to 40 as shown in the dash. Engine temp reading reaches almost 1/2 on the indicator with A/C always on. Stop and go traffic where my speed averages 13-18kmh as indicated on the on-board computer. That is why I use 15w40. I think that 5w30 will be too thin. 

Must just point out that isn't a quote of anything I've said.

[Quint]

3 hours ago, mjt said:

Must just point out that isn't a quote of anything I've said.

Sorry, I didn't know how that happened. That's actually what I wrote. Hmmm....weird. 

[andypsp]

7 hours ago, mjt said:

Engine temp reading reaches almost 1/2 on the indicator with A/C always on. Stop and go traffic where my speed averages 13-18kmh

air-con will keep your mpg lower than it should do i think as you always have it running. and the slow moveing traffic will not do you mpg too good eaither 

[mjt]

It's happened again, but I think (hope) it's because Andy quoted Quint's post which had already incorrectly attributed me.