Loss in mpg after service - any ideas?

Loss in mpg after service - any ideas?

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topless360

Original Poster:

2,763 posts

218 months

Wednesday 26th November 2014
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We had my wife's 1 litre Ecoboost Fiesta serviced last week (25k miles, 15 months old). The service consisted of an Oil, Oil Filter and Pollen Filter change.

However, since the service I have noticed that the mpg has dropped and there is a slight hesitation during gentle acceleration when cold. For the last 25k miles I have reset the mpg counter each week and it has never dropped below 50, usually it's in the range 51-55.

Since the service we've done 2 resets, the first time it was in the 49's and now it's in the 47/48's. Nothing has changed, her commute is exactly the same and she is driving in the same way she always has done.

It also has nothing to do with the cold weather as the car was getting easily 51+ throughout all of last winter.

Ford are taking it back tomorrow to re-check everything, but anybody have any ideas what could be causing the slight hesitation and drop in mpg? The worry I have is that it's such a small change in behaviour that it will make the problem hard to diagnose.

Crusoe

4,068 posts

231 months

Wednesday 26th November 2014
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petrol station changed to winter fuel mix, low tyre pressures, thicker grade of oil (not sure how you check but the new fords need a more performance orientated thinner oil than most of the range), airbox lid or similar not located correctly.

Jimmyarm

1,962 posts

178 months

Wednesday 26th November 2014
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Did they do a software update to it ?

iloveboost

1,531 posts

162 months

Wednesday 26th November 2014
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Jimmyarm said:
Did they do a software update to it ?
That's what I was thinking. Sometimes they do an update as part of a service. A slight variation in mpg even doing exactly the same journey/s is normal though.

Conscript

1,378 posts

121 months

Wednesday 26th November 2014
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Surely the car would been sat still with the engine running at high speed for a while when they did the emissions test. If you're relying on your average mpg count, maybe that's skewed the figure slightly?

Edit: ignore, just saw the bit where you said it's been reset since, sorry!

topless360

Original Poster:

2,763 posts

218 months

Wednesday 26th November 2014
quotequote all
Jimmyarm said:
Did they do a software update to it ?
Not that I'm aware of, but I'll double check with them tomorrow.

The tyre pressures have definitely remained constant as I check them regularly and have done so since the service. The petrol mix is an interesting point but I doubt it as we've filled up twice in that time and it's never happened in the last 15 months, we always fill up at the same place.

One possible theory I have is that they used the wrong oil, the Ecoboost needs 5W20 which isn't a mainstream grade so maybe they put in the wrong oil by mistake? You'd certainly hope not being a Ford dealer but stranger things have happened.

I'll update after the dealer has had a chance to diagnose it.

vikingaero

10,303 posts

169 months

Wednesday 26th November 2014
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topless360 said:
It also has nothing to do with the cold weather as the car was getting easily 51+ throughout all of last winter.
It can be everything to do with the cold weather! Long cold start cycles, engine running rich, lights on more often, fan on top demist, rear demister, maybe use of a/c to aid demist.

alistair1234

1,131 posts

146 months

Wednesday 26th November 2014
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Weather. It's got colder all of a sudden, my MPG has gone down.

Alex

9,975 posts

284 months

Wednesday 26th November 2014
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Check the oil grade that they used. Modern engines are often specified with very thin oils for economy and performance.

My Subaru BRZ takes 0W20 oil, but at its first service, the main dealer had fitted 5W40 oil (I wasn't happy).

A quick Google suggests that the specified viscosity for the Ford Ecoboost 1.0 engine is 5W20. It wouldn't surprise me if the dealer has used 5W40.

TheBALDpuma

5,842 posts

168 months

Wednesday 26th November 2014
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I can't imagine Ford would get the oil wrong on one of their current models.

My bet is just a few weeks of bad traffic so slightly worse mpg. I can get 24/25mpg if I don't hit too much traffic. I'm currently getting 22mpg as the traffic has been heavy this week. Same commute, no change in my driving style, just heavier traffic.

vikingaero

10,303 posts

169 months

Wednesday 26th November 2014
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Also rain. Driving in rain creates a large amount of aero drag and tyre drag. Everyone normally thinks if it's slippery they'll get great MPG - lightly moist you may.

Alex

9,975 posts

284 months

Wednesday 26th November 2014
quotequote all
TheBALDpuma said:
I can't imagine Ford would get the oil wrong on one of their current models.
My Subaru dealer did on my BRZ.

alistair1234

1,131 posts

146 months

Wednesday 26th November 2014
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Actually, wasn't there another thread about this type of engine where a guy had done big miles in a short period of time and it was knackered?

Craikeybaby

10,403 posts

225 months

Thursday 27th November 2014
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Alex said:
TheBALDpuma said:
I can't imagine Ford would get the oil wrong on one of their current models.
My Subaru dealer did on my BRZ.
Going back 15 years I had a Saturday job at the village Ford dealer - they just used the same oil for everything...

IanCress

4,409 posts

166 months

Thursday 27th November 2014
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TheBALDpuma said:
I can't imagine Ford would get the oil wrong on one of their current models.
There was a thread a couple of weeks back where a guy had his Focus 1.0 Ecoboost serviced by Ford and they'd used the oil for Zetec engined cars, not the correct 5/20 ecoboost oil.
His engine died (not neccesarily down to the oil) and Ford paid to replace it.

Is the oil spec mentioned on the invoice?

TheBALDpuma

5,842 posts

168 months

Thursday 27th November 2014
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Turns out I could be wrong in my confidence in Ford then!

anonymous-user

54 months

Thursday 27th November 2014
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It very possibly coincides with the recent drop in temperatures. I always loose a couple of MPG in the cold, and that's consistent across countless different cars.

thatdude

2,655 posts

127 months

Thursday 27th November 2014
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In winter your engine will be staying on the cold-running map for a bit longer (takes longer to get up to temp), the use of ancillaries (heating, headlights) will place load on the alternator which may change the engine idle speed (does on my honda civic) and of course tyre pressures may never get up to their full "warm" pressures, since the ambient temp is cold, so a little more rolling resistance there.

I had one fill of semi synthetic oil in my honda civic (a mistake I realised only after I put it all in!) and noticed a rough drop of about 4 mpg.

Any binding calipers?


BritishRacinGrin

24,639 posts

160 months

Thursday 27th November 2014
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Only thing I can think of which hasn't been suggested already is maybe they overfilled the oil?

Sump

5,484 posts

167 months

Thursday 27th November 2014
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My MPG has gone from 22 to 19 in the last couple of weeks...no ones touched it so it must be weather related.