- Use regular diesel from a reputable brand

- Put a new air filter in, it's simple and not going to hurt and a blocked one will certainly increase MPG

- Winter diesel or diesel with extra life preservatives in it can cause slightly lower MPG

 

As above how many miles, the fuel filter does make a notable difference, but not as big as above.

When I changed mine, I found it easier to get a couple of extra MPG and potentially a bit more responsive/quieter. Certainly nothing like you're seeing and that was at 70-80k miles.

 

Have you checked the temperature sensors?

Have the DPF and it's sensors been checked?

If the car thinks it's cold, even when it is not, then it will use more fuel. Ditto if the DPF thinks it needs to regen.

 

Check the oil level and see if it goes up. If it does (unlikely) then regens are going on, getting intereupted and the extra fuel is ending up in oil.

I will add, I don't think it's a common on VW engines, but I know it happened on other brands.

 

 

Edited 20 November, 20205 yr by cheezemonkhai

Hello e-Roottoot,

Many thanks for reply. 

Yes, welcome to the forum will be soon. Regarding your questions I will try to better explain. 

 

Q: How many miles had the car done when you got it and how many now?

I bought that car with 31198 miles on a clock, now I have 40185 miles.

 

Q:How often is the car doing regens?

A: Not sure what are you asking for. What I have observed is that the car quite often has higher idle rpm, about 1000 instead of normal 750. I assuming that is a DPF cleaning.

 

Q: Why not give the very expensive Shell V-Power a miss and even their Regular Diesel and go brim the tank someplace else.

A: Are you suggesting that there is something wrong with the fuel? I can go and refuel on other station, but how this might impact mpg?

 

Q:Saying per tank gives no idea of how many miles per liter you are getting.   Is there a nice clean air filter fitted?

A: There is about 40 liters sometimes 42 liters during refueling and I am doing 280 miles. I've done math, for calculation I took 41 liters for a tank. As a results came up:

1. That currently my fuel efficiency is as an average 31.1 miles / gallon or 9.1 liters / 100 km. 

2. For previous mentioned 450 miles per tank that efficiency is as an average  50 miles / gallon or 5.62 liters / 100 km.

That is is a bit what I can see. Previously I had to to about 100 miles until fuel gauge start moving down. Now it is just 40 miles. At the moment I have just bit more than half tank and I have done 130 miles. 

Regarding air filter, it was replaced on the 1st July (main service in Skoda), but in the mean time I was driving in rural area where was a lot of dust. I will check how actually it is looks now. 

 

Regards

 

3 hours ago, Florian_pl said:

Hello e-Roottoot,

Many thanks for reply. 

Yes, welcome to the forum will be soon. Regarding your questions I will try to better explain. 

 

Q: How many miles had the car done when you got it and how many now?

I bought that car with 31198 miles on a clock, now I have 40185 miles.

 

That's low, the fuel filter isn't due until about 80k miles, so I would think that is one of the last places to look unless the car was sat for a long time with a part full tank and bacteria built up in the tank. That however would show up as other problems.

 

Quote

 

Q:How often is the car doing regens?

A: Not sure what are you asking for. What I have observed is that the car quite often has higher idle rpm, about 1000 instead of normal 750. I assuming that is a DPF cleaning.

 

That sounds like it.

If you're doing a lot of town driving it may never clear.

 

Quote

 

Q: Why not give the very expensive Shell V-Power a miss and even their Regular Diesel and go brim the tank someplace else.

A: Are you suggesting that there is something wrong with the fuel? I can go and refuel on other station, but how this might impact mpg?

 

The shell is fine, but when I tried a couple of tanks, I found whilst it claimed to be cleaner I got slightly worse MPG from it than from the standard shell Diesel.

Worth a shot, but you're talking a couple of mpg, not big differences.

 

Quote

 

Q:Saying per tank gives no idea of how many miles per liter you are getting.   Is there a nice clean air filter fitted?

A: There is about 40 liters sometimes 42 liters during refueling and I am doing 280 miles. I've done math, for calculation I took 41 liters for a tank. As a results came up:

 

If you're even slightly competent with a screwdriver then an air filter is easy to do and at 40k miles if it hasn't been done (Unlikely) then it is due a change.

 

Quote

1. That currently my fuel efficiency is as an average 31.1 miles / gallon or 9.1 liters / 100 km. 

2. For previous mentioned 450 miles per tank that efficiency is as an average  50 miles / gallon or 5.62 liters / 100 km.

That is is a bit what I can see. Previously I had to to about 100 miles until fuel gauge start moving down. Now it is just 40 miles. At the moment I have just bit more than half tank and I have done 130 miles. 

Regarding air filter, it was replaced on the 1st July (main service in Skoda), but in the mean time I was driving in rural area where was a lot of dust. I will check how actually it is looks now. 

Was it replaced as unless you're billed for it, it's not included in a major service until about 60,000 miles.

 

 

Has that tank of fuel been in the car over lockdown?

Has the car battery had a good charge, either through a long run on the motorway etc or on a charger?

 

Again it's a case of trying to narrow things down.

 

Also did the dealer do a scan with your sevice? Same goes if you have or know anyone with VCDS, as that might be able to give some clues.

Edited 20 November, 20205 yr by cheezemonkhai

Hello,

A bit of updates what I have done, but first questions for which I am appreciated.

On 20/11/2020 at 15:02, cheezemonkhai said:

 

Has that tank of fuel been in the car over lockdown?

I was not driving much during lockdown, but definitely I had to refueling once or twice.

 

On 20/11/2020 at 15:02, cheezemonkhai said:

Has the car battery had a good charge, either through a long run on the motorway etc or on a charger?

During 2 weeks of my holiday I have done trip to Poland and back. It had a good charge.

 

On 20/11/2020 at 15:02, cheezemonkhai said:

Also did the dealer do a scan with your sevice? Same goes if you have or know anyone with VCDS, as that might be able to give some clues.

I have been in Skoda with this issue they have saide that they scan the car and no errors were found. I have done scanning today with "car scanner" and no errors were found.

On 20/11/2020 at 08:53, cheezemonkhai said:

Have you checked the temperature sensors?

Have the DPF and it's sensors been checked?

If the car thinks it's cold, even when it is not, then it will use more fuel. Ditto if the DPF thinks it needs to regen.

I have done scanning of my car and looks like DPF is OK, anyway I am going to check DPF more cerfully with propper app for DPF.

 

Back to the car, today I have checked airfilter, pictures attached. I am not an expert, does this need replacment?

During checking car two things captured my eye

1. Fuel consumprtion durring idle, it was 2.3 liter per hour. No A/C or mirros heating, just engine. I was expecting values about or below 1 lietr per hour, see attached pictures.

2. Emission test, there are few points which has failed. Is it something which I should worry? Just to add on Monday I have scheduled MOT, wonder now if I will pass it. See attached pictures.

 

During car scanner there were a lot of sensors and readings. For most of them I have no idea what they are showing. Can someone advise on what I should focus on?

Please see screen shots from the app in zip file.

 

Regards.

 

carscanner.zip

I would change the air filter as I would say it’s due. That will be different to the official Skoda line no doubt.
 

I use Skoda or Mann Filter.

 

Whilst that will give a slight improvement in mpg and generally allow the engine to work more cleanly, I doubt it is all if it.

 

The mpg seems a bit high to me, but temperature and many other things can affect that. 
Was the car at or above 1000rpm then?

If so I do suspect something in the emissions control systems causing dpf regeneration.

 

When the oil was changed was it with VW507 and not anything else? VW507 must be used on all dpf cars as it is low ash.

An indicated consumption figure of 2.3L/hour at idle with no ancilliaries running is very high.

I have not owned a diesel with a dpf filter but my old 1.9pd diesel in the mk2 used to show 0.5L/hour at its natural 900rpm idle when warm.

 

Even my current 1.4tsi display shows 0.5L/hr at idle in similar circumstances.

 

Sounds like the car is locked into a permanent and continuous regeneration?

 

Only with the aircon on at full blast during a 47 degree day have I seen idle consumption near 2L/hour.

Hello Guys,

Thanks for feedback

On 22/11/2020 at 10:21, cheezemonkhai said:

Was the car at or above 1000rpm then?

No it was not, rpm were about 750.

 

On 22/11/2020 at 10:21, cheezemonkhai said:

 

When the oil was changed was it with VW507 and not anything else?

The oil and oil filter has been changed at 1st July. I have been in Skoda so I am assuming that they have put correct one.

 

On 22/11/2020 at 21:38, Gerrycan said:

Sounds like the car is locked into a permanent and continuous regeneration?

The readings showing that DPF is OK,

 

I have done small sesion to capture few parameters to see how they are behave during stop and drive, I have combined three pictures of different parametes with reflect to rpm.

Part 1 is showing air temp and MAF, from some strange reason readings has stoped recording. It might be that I have clicked someting during short breake.

Part 2, air/fuel ratio normally should be about 14.7. What I can see it is about 4 and sohastically going up when rpm increasing. Does it should be conversely? I am not sure this variability, it does not look good for me.

Part 3, readings of O2 sensor (lambda sensors). What I have read is that the mA should be around 0 mA otherwise fuel mixture is rich or lean. What I do not like again is this vairability. O2S1 looks like have higher values constantly where O2S2 has proper values on the begining, but the end is rubish.

Basically when I was googling I have found information that so high increase consumption of the fuel is matching with lambda sensor failure (up to 50% higher consumption and less power during acceleration). There is just one problem, there is no DTC error. Any ideas what it might be? Sympthoms are muching to lambda sensoer failure, but there is no error.

I have been today to do MOT and surprisedly I have passed MOT.  After my findings I was pretty much sure that I will fail MOT, but I did not. In the service they have explained to me that for diesel they are not doing the same emmision test like for petrol engine.  Anyway they have ignored me when I started talking about my readings. For them there is no error so there is no problem.

I will be much appriciated if somone can have a look on my readings and advice what I should do next. I would prefer to take some more measuremnts from the car to better understand what is happening rather that replacing bit by bit.

You could disconnect the MAF sensor and get comparative readings.

 

The car has a default program which will not have the car running well but will help to diagnose things.

 

If you disconnect the MAF wire and fuel economy improves, you then know that is a good place to start.

 

I take it you have checked the intake is free from obstructions (leaves etc) and also checked the exhaust for leaks/holes?

 

You are getting to the limits of my knowledge here, so the above are based on things I have seen/had on other cars in the past now.

Edited 25 November, 20205 yr by cheezemonkhai