BP2411

Fiesta MK7 1.4 TDCI mpg

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Hello everyone, just wondering what sort of mpg people are getting out of theirs?  I only really use it for work & back (4 miles each way) and I get about 25 mpg! It's recently been really bad, not sure if it's due to the cold weather or the price of fuel or if something more sinister is to blame.

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The price of fuel has no effect on miles per gallon.  Just pence per mile.  But it's dropped a bit recently anyway lol.

With the high winds and short town journeys mine has been bad this week...I was sitting on 35mpg after half an hour yesterday. 😮  Fortunately the tank average is still above 50mpg but I do one longer journey a week which makes up for the short ones.  

That said, 25mpg from a 1.4 TDCi sounds absolutely horrific, I've had 20 year old, 2.0 petrols doing better MPG than that lol.  Have you got access to Forscan to check for any faults?  Are any of the brakes binding?  Has the EGR been blanked?

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That does seem very low I get more than that in an ST, have you looked at having de-carbonised? Using something like Terraclean

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25mpg!!  Last time I was getting that was in a 320hp Mazda 3 MPs. 

Tdci is not exactly the best vehicle to go 4 miles each way in. 

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I do have forscan, I'll scan later

no breaks binding

Egr isn't blanked but was removed & cleaned recently, glow plugs were also changed recently

I haven't looked into de-carbonising yet but due to the mileage (175k) I think it's due is there something I can do myself first like redex (but not so controversial lol)

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I would not risk a carbon clean on a 175k DV4 lol.

There are more expensive Redex type additives, Millers or Archoil for example, but tbh they're unlikely to give you the 20mpg that you've lost somewhere.

I'd be checking for injector leaks next.

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I had the seals changed on the injectors within the last 18 months - 2 years and I do very little mileage so I'd be fuming if it was them again but something is definitely wrong.

What's my best option for something I can add to the tank to get any gain in mpg? 

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1 minute ago, BP2411 said:

I had the seals changed on the injectors within the last 18 months - 2 years and I do very little mileage so I'd be fuming if it was them again but something is definitely wrong.

What's my best option for something I can add to the tank to get any gain in mpg? 

In my experience I haven't found any additives to increase MPG noticeably so don't bother any more.

Do you get any black exhaust smoke that might indicate a boost leak?

It may even be the injectors themselves at fault, especially if they're still original and not been refurbed with that mileage?

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No signs of any problems bar shocking acceleration but it's been like that since I bought it.  I've had the car 3 years in May and I haven't had the injectors changed in that time, not sure if any of the previous owners did it though.

Oil & filter were changed May 2018, cabin & air filter haven't been changed since May 2016, if the air filter could be a suspect?

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I've never changed it but after the nightmare I had trying to start the car after I had to remove it to clean the egr I'd rather burn the car than change it lol

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When I removed it to clean the egr valve I had to lend a syphon pump to get it started again (3 days later) as ford decided not to put the hand primer on the MK7 for some reason.

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It's easy enough if you have a primer to hand.what your issue was due to the time left removed, the fuel in the lines flowed back into the tank . Alot of air to draw out using a Syphon pump. 

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I've seen people do it with a brake bleeding kit, do you have a link to a primer?

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There are thousands on ebay - https://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&_sop=15&_nkw=diesel hand primer&rt=nc&LH_PrefLoc=1&_trksid=p2045573.m1684

Or head to the scrap yard and get one from an older Fiesta/Peugeot/Citroen.  

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No faults found with forscan, would injectors or fuel filter show on forscan though? I'll go for the filter first due to the mileage and the fact I've never changed it .

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They may not show codes, but you can use Forscans live data readings to determine the condition of both. 

Fuel filter is definitely worth doing if it's not been done though.

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Is there a guide on how to check live data? What sort of ranges am I looking for?

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There's loads of live data available on Forscan, it's all very intuitive though so just have a go.  The main ones to check here are requested fuel pressure against actual fuel pressure.  If there's a big discrepancy, particularly at higher rpm, then the filter may be restricting flow.  The other one is injector corrections, they should be roughly the same across all 4, if one or two are very different then it's worth doing a physical leak off test (YouTube that one) to confirm injector wear.

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Had another go on forscan the other day but couldn't see how to get requested fuel pressure vs actual fuel pressure or the injector corrections.  Fuel filter is definitely on the to do list but I wanted to check it before & after to see any improvements.

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Found this on another site, hopefully it's right to test injectors, then I'll just need to find out how to see actual Vs requested fuel pressure.

1. Run & connect, go to Dashboard section
2. Double click on a dashboard or press Setup button, PIDS selection dialog will be opened. Select ICU module. Select PIDs CYL1_RATIO, CYL2_RATIO, CYL3_RATIO, CYL4_RATIO and click OK. 
3. Run the engine, wait until engine speed is stabilized at idle. 
4. Click Start button and monitor 

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