Hello

 

I can't work out why my fabia is doing 7 mpg less than normal. 

 

on a 30 min town + motorway journey i was doing around 60 mpg.  After an oil change, 3 days later the economy dropped. I got no smoke coming out, no lights, i filled up with premium then regular diesel and no change on either. 

 

Now I try very hard to drive as economically as possible and still don't reach the 60's. Still doing 53 to 54 mpg which is not bad but i don't know what has changed.

 

What i looked for so far:

- boost leaks. I sprayed soapy water on the intercooler/turbo pipes, asv valve, but no bubbles came out while revving. 

- i took off the driveway 10 seconds after i turned the engine on so no extra fuel was used. 

- i did an oil change with the recommended oil + filter (can this be it?).

- i drove it hard on the motorway to clear the DPF. I don't do any extra regens 

- i sprayed the MAF sensor with electrical cleaner

- i got my gf to drive behind me and checked on the dashcam for tailpipe smoke.

- i check the oil every week and it's all the same

- checked tyre pressure but that didn't change.

- i don't use AC

 

I read somewhere that an EGR leak might do this. Also an O2 sensor could be the issue. However i haven't got any warning lights , never had one. 

 

Cold weather (although it should improve)? Magic? Life?

 

let me know your thoughts.

 

Bertie

 

 

 

Ive noticed a decrease in MPG since the cold weather has set in! Car idles higher for longer before warm so will use more and driving to and from uni I have dropped about 3-4 mpg. More air means more fuel and colder air means more power so it could be that even if its colder the cars using more fuel. I am not expert but might be the cause. 

 

 

 

4 minutes ago, JGrindel said:

Ive noticed a decrease in MPG since the cold weather has set in! Car idles higher for longer before warm so will use more and driving to and from uni I have dropped about 3-4 mpg. More air means more fuel and colder air means more power so it could be that even if its colder the cars using more fuel. I am not expert but might be the cause. 

 

 

 

i heard this many times yes. I heard so many scientific explanations on denser air less fuel blah blah blah i'm more confused than before. it was the time when the cold weather came around. But when it went back to 12*C the fuel consumption never went back how it was. 

Could be your thermostat, mines not the same engine but I had an issue with low fuel economy made worse in this cold weather and turned out to be a faulty stat, would not open at the right time to car was cold for too long and never sat at the right temperature

The ECU will make ever so slight adjustments to the map as you drive it so maybe one drive in warmer weather isn’t going to allow the ecu to change again? I might be wrong as a map is a map but I have been told they do adjust slightly as you go. 

7 minutes ago, clarendon462 said:

Could be your thermostat, mines not the same engine but I had an issue with low fuel economy made worse in this cold weather and turned out to be a faulty stat, would not open at the right time to car was cold for too long and never sat at the right temperature

i do notice the needle wobbling a bit up and down when getting up to temperature. And even when the coolant it's all hot 90*C, when i turn the fan on the revs go up to 1000 like it has to work harder to give me heat. When i turn the fan off the idling goes back to 800.  #firstworldproblems

Edited 4 December, 20178 yr by Bertie90

I wouldnt worry about a couple mpg loss... It also could be due to cold weather diesel which has more additives to stop if freezing into gloop

 

So was the oil that went in the same as before only new oil?

You check your tyre pressures as the weather changed,  so was that checked cold? 

By now you will have winter spec diesel in your filling stations but that does not make a real difference.

Cold weather, swings and roundabouts, better combustion, less toad traction/ friction, lights on, rear screen, heated mirrors,

so mony a mickle maks a muckle. Little differences add up.

2 minutes ago, JGrindel said:

I wouldnt worry about a couple mpg loss... It also could be due to cold weather diesel which has more additives to stop if freezing into gloop

 

 

2 minutes ago, AwaoffSki said:

So was the oil that went in the same as before only new oil?

You check your tyre pressures as the weather changed,  so was that checked cold? 

By now you will have winter spec diesel in your filling stations but that does not make a real difference.

Cold weather, swings and roundabouts, better combustion, less toad traction/ friction, lights on, rear screen, heated mirrors,

so mony a mickle maks a muckle. Little differences add up.

 

I think i'm getting at a stage where i'm OCD about figures, mpg, how many regens, knock, wobble squeak. Yeah, another thing....why does my suspension squeak ( like you would make two balloons rub) when i go over speed bumps? It does it only when it's freezing and it so noticeable, even people that are not car people notice it and ask me questions. 

 

 

I'm thinking to switch my MFD to Audio only and turn the volume up.

Just now, Bertie90 said:

 

 

I think i'm getting at a stage where i'm OCD about figures, mpg, how many regens, knock, wobble squeak. Yeah, another thing....why does my suspension squeak ( like you would make two balloons rub) when i go over speed bumps? It does it only when it's freezing and it so noticeable, even people that are not car people notice it and ask me questions. 

 

 

I'm thinking to switch my MFD to Audio only and turn the volume up.

I get OCD about numbers too... like I get annoyed when its at like 45mpg... my buddies with petrol cars get annoyed at me for thinking 45mpg is bad...! My suspension sounds like garbage... speed bumps are taken at 10-15mph now due to lower springs! Music up and everything sounds top notch

Tank to tank fill up is all that matters, see if you are really getting as much as 70 miles less from near 10 gallons of fuel as when the weather was a bit warmer.

2 minutes ago, AwaoffSki said:

Tank to tank fill up is all that matters, see if you are really getting as much as 70 miles less from near 10 gallons of fuel as when the weather was a bit warmer.

yes that's what i'll do. It might have been the MFD was telling me lies before and now it's the right answer.

 

5 minutes ago, JGrindel said:

I get OCD about numbers too... like I get annoyed when its at like 45mpg... my buddies with petrol cars get annoyed at me for thinking 45mpg is bad...! My suspension sounds like garbage... speed bumps are taken at 10-15mph now due to lower springs! Music up and everything sounds top notch

My GF has a yaris petrol 09 plate. I swear that thing never had any work done apart from maintenance. She takes roundabouts in 4th gear, she changes gears like she's and f1 driver, never avoids a pothole and only fuels up with supermarket fuel. Not even once that car had an issue. And I tinker with my fabia every weekend, change gears perfectly and then the lower gearbox mount goes wtf!!! Then an injector goes, then a boost leak. Still best car i ever had lol  

1 minute ago, Bertie90 said:

yes that's what i'll do. It might have been the MFD was telling me lies before and now it's the right answer.

 

My GF has a yaris petrol 09 plate. I swear that thing never had any work done apart from maintenance. She takes roundabouts in 4th gear, she changes gears like she's and f1 driver, never avoids a pothole and only fuels up with supermarket fuel. Not even once that car had an issue. And I tinker with my fabia every weekend, change gears perfectly and then the lower gearbox mount goes wtf!!! Then an injector goes, then a boost leak. Still best car i ever had lol  

I took the **** out of my gf when she paid Mini to do an a/c service on her car while it was in for a regular service. I was saying how it was a dealer scam and not worth it etc etc... 1 month later my cars in the garage having a new a/c compressor fitted with a whopping £500+ repair bill... I guess these a/c services might not be as much as a scam as I thought.... 

Deffo noticed a decrease since the cold weather 

i'll go with the weather 

AMD87, the Winter diesel started getting delivered from just near you mid October.

 

?

Was the 65 mpg on a longer trip from a tank or is that a common good economy?

23 minutes ago, AMD87 said:

Deffo noticed a decrease since the cold weather 

what app is that?

Road trip 

9 minutes ago, AwaoffSki said:

AMD87, the Winter diesel started getting delivered from just near you mid October.

 

?

Was the 65 mpg on a longer trip from a tank or is that a common good economy?

Long trip from Sheffield average is mid 40s around town. 

 

Also with the cold cold weather I’ve been sitting in my car on my breaks at work with the engine and heater on which won’t be helping things. 

Solved

I just used a tank of fuel and it turns out that i have been achieving the same miles as before. The computer was showing 60 mpg average  but when calculated how much fuel i put it and how many miles I've done, it equates to 49/50 mpg. 

After the service and cleaning the MAF sensor and the ASV valve it seems to have changed to 50 mpg but the distance achieved is exactly the same as before. 

 

So it was all a computer thing......

40 minutes ago, Bertie90 said:

Solved

I just used a tank of fuel and it turns out that i have been achieving the same miles as before. The computer was showing 60 mpg average  but when calculated how much fuel i put it and how many miles I've done, it equates to 49/50 mpg. 

After the service and cleaning the MAF sensor and the ASV valve it seems to have changed to 50 mpg but the distance achieved is exactly the same as before. 

 

So it was all a computer thing......

Good to hear you've sorted it!! Damn technology... 

So drove back from work today, and that presume economy came back. Keep in mind it's mostly city driving, lots of hills and a few stretches of roads.  65mpg!!!

Sort it out 

18 hours ago, AMD87 said:

Sort it out 

He clearly was driving the Skoda way! Unlike us yellow tinted boy racers  

36 minutes ago, JGrindel said:

He clearly was driving the Skoda way! Unlike us yellow tinted boy racers  

 that was after a 4 hour trackday.