This post is offered from recent experiences.
The car is a Qubo 1.3 Multijet Trekking 95HP on a 67 plate with 90K on the clock
Summary :
- if your MPG is falling off, it may be that your IAT sensors are getting mucky and could benefit from cleaning
- If you’re running on ordinary diesel you may get a surprising increase in mpg (and performance) by using a ‘Super’ diesel fuel
Discussion :
IAT and mpg
We’ve had the car since March 2023. It’s a bit niche but we needed that precise size and carrying space.
At the start I was disappointed by the performance and fuel consumption (mid-40s mpg). Changing the filters and running on Shell V-Power made a positive difference after a couple of months. But the consumption was still lower than expected (around low 50s mpg) and starting to get worse.
Then the EMS showed the engine block symbol on the dash and code P0096 was diagnosed; you can find information about that in this forum but basically P0096, in our case, related to the two IAT sensors not agreeing (within margins).
Having had both a Punto and a Marea some years ago which both had failed Mass Air Flow sensors, at about the age and mileage of our Qubo, getting a problem with similar sensors at 90K did not surprise me. The easiest IAT (‘Sensor 1’) to access is that in the air intake pipe (on the left side of the engine / before the air filter); it is in the MAF. That was changed; the mechanic said that it was mucky. After quite a few startup cycles, a week or so later, the EMS message showed again. Grrr. This time Sensor 2 was replaced – that’s trickier to access being at the top rear of the engine and needing a torx on a ratchet. The mechanic stated that it was very mucky and would not have been worth cleaning (his time vs cost of part). Since then (August ‘24) the car is sprightlier and with good mpg – high 50s to low 60s; more about that further on.
So, if your mpg is falling off, it may be worthwhile to get at the sensors and see if they could do with a good clean.
‘Super’ diesel and mpg
Background : I’d used Shell V-Power diesel on our Doblo (2013-2023) and had compared several back-to-back tanks of ordinary to several of V-Power to see what differences there might be. The V-Power gave about 15% extra mpg for 10% higher cost; plus more response for overtaking etc.
Why V-Power ? Well, I’d heard of it – ages ago - as being worth a try and the Shell garage is much closer than, eg, BP or Esso. I’ve not compared the premium diesels.
In September 2024 we drove to Italy. All on Auto-routes/bahnen/strade. Mainly on level surfaces running at 65-70mph with little head-wind. About 2,000 miles round trip with 7 days on the road.
In the 18 months or so that we’ve had the Qubo it has been filled with V-Power so we started off with a full tank of that from Dover and didn’t come across any form of ‘Super’ diesel at any of the forecourts at which we stopped (mainly in suburbs or small towns). Covering about 270 miles per day which used a bit over the half-way mark on the fuel gauge. Over the 7 driving days the amount of V-Power became diluted (estimated at 40% of each tankful remaining before top-up) so that by the final day less than 1% of V-Power remained.
On day 1, to Saarbrucken, the mpg was 61. On the last day, from Troyes to Dunkerque, that had dropped to 49, having been steadily falling day by day. Didn’t need to push the engine for acceleration while on the motorways so didn’t notice any drop off in oomph.
For me, that difference in mpg was an emphatic QED. The EMS problem had been resolved so the engine was probably in as good a condition as it could be (bearing in mind it’s done 90K). This limited trial showed V-Power providing about 25% increase in mpg for – in UK costs – about 14% extra. So I’ll stick with V-Power.
Might be worth you trying it out ? Mind you, it might take a couple of tankfuls to clean/prime the fuel system.
The car is a Qubo 1.3 Multijet Trekking 95HP on a 67 plate with 90K on the clock
Summary :
- if your MPG is falling off, it may be that your IAT sensors are getting mucky and could benefit from cleaning
- If you’re running on ordinary diesel you may get a surprising increase in mpg (and performance) by using a ‘Super’ diesel fuel
Discussion :
IAT and mpg
We’ve had the car since March 2023. It’s a bit niche but we needed that precise size and carrying space.
At the start I was disappointed by the performance and fuel consumption (mid-40s mpg). Changing the filters and running on Shell V-Power made a positive difference after a couple of months. But the consumption was still lower than expected (around low 50s mpg) and starting to get worse.
Then the EMS showed the engine block symbol on the dash and code P0096 was diagnosed; you can find information about that in this forum but basically P0096, in our case, related to the two IAT sensors not agreeing (within margins).
Having had both a Punto and a Marea some years ago which both had failed Mass Air Flow sensors, at about the age and mileage of our Qubo, getting a problem with similar sensors at 90K did not surprise me. The easiest IAT (‘Sensor 1’) to access is that in the air intake pipe (on the left side of the engine / before the air filter); it is in the MAF. That was changed; the mechanic said that it was mucky. After quite a few startup cycles, a week or so later, the EMS message showed again. Grrr. This time Sensor 2 was replaced – that’s trickier to access being at the top rear of the engine and needing a torx on a ratchet. The mechanic stated that it was very mucky and would not have been worth cleaning (his time vs cost of part). Since then (August ‘24) the car is sprightlier and with good mpg – high 50s to low 60s; more about that further on.
So, if your mpg is falling off, it may be worthwhile to get at the sensors and see if they could do with a good clean.
‘Super’ diesel and mpg
Background : I’d used Shell V-Power diesel on our Doblo (2013-2023) and had compared several back-to-back tanks of ordinary to several of V-Power to see what differences there might be. The V-Power gave about 15% extra mpg for 10% higher cost; plus more response for overtaking etc.
Why V-Power ? Well, I’d heard of it – ages ago - as being worth a try and the Shell garage is much closer than, eg, BP or Esso. I’ve not compared the premium diesels.
In September 2024 we drove to Italy. All on Auto-routes/bahnen/strade. Mainly on level surfaces running at 65-70mph with little head-wind. About 2,000 miles round trip with 7 days on the road.
In the 18 months or so that we’ve had the Qubo it has been filled with V-Power so we started off with a full tank of that from Dover and didn’t come across any form of ‘Super’ diesel at any of the forecourts at which we stopped (mainly in suburbs or small towns). Covering about 270 miles per day which used a bit over the half-way mark on the fuel gauge. Over the 7 driving days the amount of V-Power became diluted (estimated at 40% of each tankful remaining before top-up) so that by the final day less than 1% of V-Power remained.
On day 1, to Saarbrucken, the mpg was 61. On the last day, from Troyes to Dunkerque, that had dropped to 49, having been steadily falling day by day. Didn’t need to push the engine for acceleration while on the motorways so didn’t notice any drop off in oomph.
For me, that difference in mpg was an emphatic QED. The EMS problem had been resolved so the engine was probably in as good a condition as it could be (bearing in mind it’s done 90K). This limited trial showed V-Power providing about 25% increase in mpg for – in UK costs – about 14% extra. So I’ll stick with V-Power.
Might be worth you trying it out ? Mind you, it might take a couple of tankfuls to clean/prime the fuel system.
