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Discussion Starter · #1 ·
I have no doubt there are a million threads on "my MPG seems rubbish", so here is another one!

Twenty mile round trip daily commute, 70% of which is on fast dual carriageway. Getting 32 mpg.

We all know the manufacturers mpg claims are a work of fiction, but this seems ridiculous. This is a piddly 998cc 3 cylinder engine! I had a 4.0 Jaguar XK8 that I could get high twenties mpg ffs!

Just had crankshaft position sensors error and been replaced - is it possible that they would have been failing over time and contributing to bad mileage? I don't think so.

Any "real world" figures from the community would be welcome.
 

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I've owned my 1.4t (150), auto now for nearly 16 months, long term average on E10 or none premium fuel, 44mpg mixed driving at an average speed of 35mph. Happy with that.
32mpg on a long run seems low to me, I owned this engine for a short period of time and averaged lower 40's, manual gearbox, too.

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I have no doubt there are a million threads on "my MPG seems rubbish", so here is another one!

Twenty mile round trip daily commute, 70% of which is on fast dual carriageway. Getting 32 mpg.

We all know the manufacturers mpg claims are a work of fiction, but this seems ridiculous. This is a piddly 998cc 3 cylinder engine! I had a 4.0 Jaguar XK8 that I could get high twenties mpg ffs!

Just had crankshaft position sensors error and been replaced - is it possible that they would have been failing over time and contributing to bad mileage? I don't think so.

Any "real world" figures from the community would be welcome.
that’s really poor , my old 1.0t would do 40 around town and up to 60 on a-roads etc.
Any errors still Showing ? You will need a code reader to see.
You could disconnect battery for 1/2 hour and then reset everything etc .Then fill tank to brim , do a weeks driving of mixed roads then brim tank again , work out how many miles you have done to fuel put in. Might give you a more accurate figure.
 

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I agree it does sound a bit on the low side. First of all, is that trip computer or actual brim to brim figures ? My 1600 ( although not regularly) does that sort of trip when it gets used and I'm getting about 35 mpg-ish or so. My 1400 before that used to get about 32mpg. I think a lot of the poor mpg on my cars is down to the fact they're hardly ever given a decent run out. Surely if you're doing that daily on a commute to work, the figures should be a bit better ?
There is also the question of how hard do you work it during the commute ? Seems to me that the current crop of "eco" small capacity turbo engines are OK until you start to give them a bit of welly, when their fuel economy is horrible.

My old 2 litre MkIV Cortina would've been able to get 35mpg using it like that and IIRC it used to have 105bhp so a fair comparison I reckon. :ROFLMAO:
 

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I have no doubt there are a million threads on "my MPG seems rubbish", so here is another one!

Twenty mile round trip daily commute, 70% of which is on fast dual carriageway. Getting 32 mpg.

We all know the manufacturers mpg claims are a work of fiction, but this seems ridiculous. This is a piddly 998cc 3 cylinder engine! I had a 4.0 Jaguar XK8 that I could get high twenties mpg ffs!

Just had crankshaft position sensors error and been replaced - is it possible that they would have been failing over time and contributing to bad mileage? I don't think so.

Any "real world" figures from the community would be welcome.
I have a Jag XE that does that to the gallon! But we also have a 1.0T which we have owned since 2016. If we drive with foot to the floor in every gear with sport mode on you cannot get less than 37mpg. If you drive normal around town with the occasional foot to the floor moment we see 44mpg easily. On the motorway sat at 70 will see 60mpg, sitting st 80 will give 54mpg.
What mileage has your car done, is it over 40k ? Have the plugs been changed? If not it maybe worth checking them to see what condition they are in and also check the gap is the same on all plugs..they are supposedly set from the factory but you do see some with a slightly different gap and need slight adjustment.
Sorry forgot to mention we have run out 1.0t on Tesco momentum 99 from new, did try a tank of E10 when it was first introduced but the car was down on power and had a slight judder every now and again so won’t be using that again. It is also well documented that E10 gives less mpg so maybe worth trying some super unleaded for a couple of tanks and see if that helps
 

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Discussion Starter · #8 ·
Thanks all for the input, really appreciate it.

Wife is the driver and the only miles it does is her Mon - fri commute. She is a fairly timid driver so no lead footing. She does tend to change up way too early (in my opinion) - she actually takes notice of the gear change indicator! The few times I drive it I like to hang on to 2nd and third, burn a little oil! I'm old school :)

MPG numbers are from the trip rather than tank to tank. She is off on a long trip tomorrow (High Wycombe to North Wales) so I have reset the trip and have a look when she returns.

I have a code reader and there are no codes showing since the sensors were replaced (about three weeks ago).

Mileage is only 20K, I always keep the tyres at 35 psi. Oil is 0W/20. (Serviced at Vauxhall indie in January).

I do find that it really dogs on not very steep hills and I have to change to first to get up. It is always on supermarket E10 so I wonder if that has a bearing. Really can't afford Super at the moment!
 

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I do find that it really dogs on not very steep hills and I have to change to first to get up. It is always on supermarket E10 so I wonder if that has a bearing. Really can't afford Super at the moment!
I've not yet come across a hill that mine doesn't fly up,
i live at the bottom of what i would call a fairly steep hill and it pulls easily over it in third,certainly never been down to first,good luck dealing with the hills in North Wales ;)
i'm wondering if the maf on yours is working to spec,they don't always leave a fault code if underperforming rather than just plain failed or possibly the turbo underboosting a tad,
live data may reveal something.
 

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Thanks all for the input, really appreciate it.

Wife is the driver and the only miles it does is her Mon - fri commute. She is a fairly timid driver so no lead footing. She does tend to change up way too early (in my opinion) - she actually takes notice of the gear change indicator! The few times I drive it I like to hang on to 2nd and third, burn a little oil! I'm old school :)

MPG numbers are from the trip rather than tank to tank. She is off on a long trip tomorrow (High Wycombe to North Wales) so I have reset the trip and have a look when she returns.

I have a code reader and there are no codes showing since the sensors were replaced (about three weeks ago).

Mileage is only 20K, I always keep the tyres at 35 psi. Oil is 0W/20. (Serviced at Vauxhall indie in January).

I do find that it really dogs on not very steep hills and I have to change to first to get up. It is always on supermarket E10 so I wonder if that has a bearing. Really can't afford Super at the moment!
See how it goes but no way should it struggle on a hill and definately shouldn’t need to use 1st! I live in a hilly area and can get up some quite steep inclines in 4th and never need to go lower than 3rd..second gear on these cars should have you climbing a hill effortlessly.
you say you cannot afford the super unleaded..you do realise your economy will definately be down using E10, everyone I know has commented and most have started using super unleaded and seenan improvement which balances the extra cost. If you have a tesco near you try using their momentum99 which is a lot cheaper than the likes of shell and bp.
 

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One sensor that can be checked easily and cleaned if necessary is the MAP sensor which can been seen on the inlet manifold. Shouldn’t be clogged up at 20k as I checked mine at 50k and was still clean but you never know. That’s the easy one to check and clean yourself with some electrical cleaner.
Other sensors that will cause issues for bad mpg are the oxygen sensor, not expensive and quite easy to change if your mechanical minded and also the MAF sensor, again easy to replace but this one is the most expensive out of the three to change
 

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For the short period of time that I owned the 1.0t, I've never experienced any performance issues whilst driving within any conditions, hills or not. As yours is a manual, slightly less bhp than mine, mine being an auto. I'd expect to achieve slightly better fuel figures than mine on E10.
I'd go for the easy checks first, as suggested above, maybe even worth checking that your air filter is clean too. As you never know, as your car has covered 20k. Maybe a new set of plugs wouldn't harm, if they've not been changed yet? Being on an 18 plate, your Jan service should have been a major service?
On a single long trip, I get around 48 mpg, same at close to 80, too. Although I do have a 6th gear, even being an auto. Your manual box (5 speed), should at least be achieving mid 40's on a long run. I'm talking about E10 fuel, too, as I have no experience with running higher octane rated fuels.
 

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It's the obvious lack of power that would concern me,
get that sorted and the consumption figures will improve at the same time
 
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Discussion Starter · #14 ·
Thanks all. The Missus is on her way to Wales as we speak, and has just called to say the "power to engine restricted" light is on again! This is what led to the replacement of crank position sensors a few weeks ago. Odd thing is that the power is not restricted, it still drives as it always has - but maybe the power is always restricted as it struggles to go up hills. PITA.

I chose an indie specialist over main dealer as in my experience MDs tend to just replace stuff until they find the faulty component. My last indie (Jaguar) was "old school" and would actually do "proper" troubleshooting, even repairing faulty modules rather than replacing them. Hoping my Vauxhall guy is the same as I am taking it straight back on Monday! (Assuming the missus makes it back from Wales!).
 

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I don't suppose you have a record of the codes you got prior to the crank sensor change ?
 

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Discussion Starter · #18 ·
Thanks. Can't remember the P codes but they referred to crankshaft sensor A and sensor B. (I thought there was only one sensor actually but the guy replaced two so I must be wrong).
 

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The fact you posted that multiple sensors were changed is what was worrying me,
there is only the one crank sensor.
I thought that possibly you meant cam sensors of which there are two.
The Vauxhall diagnostic software doesn't usually refer to the various circuits as A or B etc
rather circuit 1,2,3 etc
the crank sensor on this engine having 3 circuits ,(5 volt reference,low reference and signal.)
 
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Discussion Starter · #20 ·
Apologies, I have found the invoice for the work and it was camshaft sensors.

The codes I got were from my (cheap) OBDII reader, I guess the garage would have more detail with Vauxhall-specific diagnostics.
 
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