Hello,

 

I have a fiesta mk7 1.25 2009 with 190k km. I do the service myself every 6-8k km (every year) with castrol magnatec A5 and new filters (Mahle). I change my spark plugs every other year and i changed them last year (about 10k ago, with NGK).

 

My daily drive has not changed (altought the temperatures have dropped to around 10ºc ~ in the winter) and i usually average 7,5-8l/100 (i log every fuel up with drivvo, and last winter it didn't change) and since the last service in the end of october i have been averaging 9l. I normamlly get 400-420km to the tank before the fuel light comes on, but i have been averaging 330 ( 4 tanks).

 

I have done a 10km without using the brakes and they are all cold, so no stuck piston/caliper, haven't seen any changes in power and the visual inspection seem all ok and checked the tyre pressures (no coolant lose aswell).

 

What can it be?

 

Thanks!

Are there any fault codes, pending?

Check live data (anything relevant) for things out of the ordinary?

I hear what you say but mileage is very dependant on so many factors however, your figures equate to 36.5 down to 31 which, IMHO  is well within normal variability (in UK we are in winter which is always worse)

Unless you can be certain you are controlling every single variable very tightly, I'd keep an eye on it for longer term trends to see if it goes back to normal?

There's also the issue of age/mileage although your good service regime should mitigate that a bit.

10 minutes ago, Shearers said:

Are there any fault codes, pending?

Check live data (anything relevant) for things out of the ordinary?

I hear what you say but mileage is very dependant on so many factors however, your figures equate to 36.5 down to 31 which, IMHO  is well within normal variability (in UK we are in winter which is always worse)

Unless you can be certain you are controlling every single variable very tightly, I'd keep an eye on it for longer term trends to see if it goes back to normal?

There's also the issue of age/mileage although your good service regime should mitigate that a bit.

I've checked with forscan and nothing ro report, what live data should i check? I'm thinking of putting new plugs, wire and distributor and see if that helps

Consider...test each plug/coil pack with a variable spark gap like this, if it will fit your ignition set up?
https://www.ebay.co.uk/itm/286158690977

Watch you don't get a shock!
Just changing stuff without some valid reason isn't my way?

Obviously, petrol (never had one since EOBD) so:

Revs (idle and say 3000 - look for differences ad sanity check - do they make sense) and air flows, EGR, turbo vane positions,  anything to do with mixture, O2 sensors, would be my best guess but isn't a good one - hopefully someone else can add.
I'm still holding to my "see if it comes back to normal/check your long term history" but that is down to your records and certainty that something has changed (but what, could it be something you have done?)

When you have a list of PIDs to look at, screenshot them for comparison with future scans

Give the T-MAP sensor a clean with MAF cleaner. Disconnect battery first to clear saved values. Basic vales will rest afterwards and you'll need to relearn basic values so run the car idle first for 15 minutes then drive for 30 minutes mixed driving condition to relearn new values. Worth cleaning the butterfly valve as well. Don't overtighten the bolts on the intake. Also worth replacing the oil breather sponge in the air box. It will be toast