BAD AVG MPG S3 2.0 FSI T Quattro

[RAG]

Hi All,

I seem to be having an issue with the MPG and hoped you guys could give some advice.

I have recently had some work done as some of you know and have had my car scanned and data logged to reset the map. The scans and data logging showed no faults at all and the tech guy said that the car is in good shape and he found no physical problems either. I know I need a new dipstick which may account for part of this issue but surely not to this extent.

I cleaned the MAF sensor and it did seem to sort the MPG issue out temporarily. However since I have had the car (3 years) the average MPG driving here and there with the occasional heavy foot was always steady at around 27mpg and up to 34/36mpg on long runs. Just recently I don't seem to be able to keep it above 20mpg.

Given my driving style has not changed and the car has no faults showing can anyone give me an idea as to what may be causing this issue?

I have had a look through some other posts but not sure any of the problems mentioned would be relevant due to no faults showing in VAG software.

As always any help is well appreciated.

 

[RS4K]

i get around 160 miles out of a full tank from stop start around town driving which is around 15mpg i think. i have had mine checked etc and have a map on it and it is all clear. i drive foot down everywhere though lol so that doesn't help

 

[voorhees]

Do the free checks first dv,leaks,clean the maf again and check the fuel trim http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info
Also if the poor economy has only been since doing work on your S3 then has everything been put back correctly ? anything damaged ? Is the work 100% right.
That is what would I would be doing if it were me ( 32 on a run to Devon is my best ever mpg )

 

[RAG]

i get around 160 miles out of a full tank from stop start around town driving which is around 15mpg i think. i have had mine checked etc and have a map on it and it is all clear. i drive foot down everywhere though lol so that doesn't help

Hi RS4K

Thanks for your reply. LOL foot down would account for that. I dont feel so bad now as I will get up to about 300 miles per tank.

 

[RAG]

Do the free checks first dv,leaks,clean the maf again and check the fuel trim http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info
Also if the poor economy has only been since doing work on your S3 then has everything been put back correctly ? anything damaged ? Is the work 100% right.
That is what would I would be doing if it were me ( 32 on a run to Devon is my best ever mpg )

Hi Voorhees,

No this problem started before any work happened to the car so not that. I will go through the the list of items you suggested and get my guy to look at the fuel trims via software next week. How would I check the DV and for any leaks (i assume hosses). I am competent and will be able to follow a guide or work out if I new location for DV but this is my first turbo car so a little different than what I am used to. Also is there a straightforward way to check for leaks?

Many thanks

 

[RAG]

Would my Revo settings have any impact on this issue? currently running B=7 T=4 F=9. Car is smooth with no flat spots and pulls all the way through the rpm.

 

[S3Alex]

Would my Revo settings have any impact on this issue? currently running B=7 T=4 F=9. Car is smooth with no flat spots and pulls all the way through the rpm.

Your settings I'm assuming haven't been changed,so that won't be the issue,and in any case wouldn't account for such a drop in mpg.

Even mine wasn't returning such poor results with Revo software at Stg4,until the throttle body started to return some very odd values,but hadn't failed in such a way that VCDS would pick it up.
It was a load correction factor that was way out,making the car run rich.

 

[nluk100]

Check the DV for splits and also check the PCV valve too as both of these are problematic. Have you replaced the spark plugs and what about the fuel filter?

 

[RAG]

Check the DV for splits and also check the PCV valve too as both of these are problematic. Have you replaced the spark plugs and what about the fuel filter?

Hi,

Thanks for your reply.

I have changed the both of these in recent months so I don't think it will be them.

What is the PSV and where is it and the Dump Valve located lol?

I am a competent DIY'er but this is my first turbo car so a little green when comes to the location of things.

 

[RAG]

Your settings I'm assuming haven't been changed,so that won't be the issue,and in any case wouldn't account for such a drop in mpg.

Even mine wasn't returning such poor results with Revo software at Stg4,until the throttle body started to return some very odd values,but hadn't failed in such a way that VCDS would pick it up.
It was a load correction factor that was way out,making the car run rich.

Hi Alex,

Thanks for your reply mate.

I think I should just ask you for advice as you seem to have a lot of experience with these cars.

How would I test the throttle body for issues? I did hear that it is meant to re align it self when you turn on the ignition but is there a way of doing this without the VCDS?

 

[S3Alex]

No probs.

The fault in mine was pretty unusual and only found comparing values from my car Vs another so I'd think it's an unlikely cause but the TB itself can cause problems which usually show up on VCDS.

I don't know if there is a manual method for doing an alignment but a good tuner ought to be able to sort it.

 

[scotty dugg]

I'm in the same boat, struggling to breach 27.0mpg on a run at 50mph.

I've to check for boosts leaks and then eventually the turbo.

Not ideal!

 

[RAG]

I'm in the same boat, struggling to breach 27.0mpg on a run at 50mph.

I've to check for boosts leaks and then eventually the turbo.

Not ideal!

Hi Scotty Dugg,

I will go through some checks and get my guy to scan later in the week and let you know if anything comes up. Might be worth trying some of the suggestions made by the guys on here aswell.

If you work it out let me know please.

 

[raffhussain]

27 MPG. That's impressive.
I drive mine mostly local and last time I checked MPG was around 18. I do have a heavy right foot though
But I when the Mrs drives it she will get maybe 20. I would have thought that would be right when your driving a S3. Correct me if I'm wrong.

 

[fernando young]

i think i'm nowhere close to 27mpg, i usually do 16-18 in heavy traffic city, maybe 20 tops doing granny driving

 

[scotty dugg]

This is constant speed in 6th no booting it. There's an underlying issue that just doesn't seem right. Bog standard car I should add.

 

[RAG]

This is constant speed in 6th no booting it. There's an underlying issue that just doesn't seem right. Bog standard car I should add.

Hi,

Sounds like I don't have issues by the comments of other AVG MPG. I have just filled up and I am going to give it a thorough check for millaeage etc. Filled up £56 to the top and reset everything so we will see what happens. I am going to try get fuel trims checked tomorrow with the VCDS and go from there.

 

[audismart]

Turn off your air con, lol.
Have you fixed the dip stick yet? most probably the housing that holds the dipstick has deteriorated and cracked, it was a common fault on 1.8t cars mk1 audis and mk4 golfs, if your car is is leaking compression then that will cause the car to run badly?

 

[RAG]

Turn off your air con, lol.
Have you fixed the dip stick yet? most probably the housing that holds the dipstick has deteriorated and cracked, it was a common fault on 1.8t cars mk1 audis and mk4 golfs, if your car is is leaking compression then that will cause the car to run badly?

LOL I have and no real difference. I have not changed the dipstick yet but one on order. Your spot on it has deteriorated and sometimes causes a little ruff idle. Still need to check other possibilities but not had the time yet. Will let everyone know when all is checked.

 

[RAG]

Morning All,

I thought I would give an update to you on this ongoing problem. I have now replaced the dipstick and still had the same problem. My guy put the car on VAG software and all is ok. He then put a camera in the manifold sensor and discovered a massive cocking up of the inlet valves. He said that he cleaned an R8 last week and it not only improved the MPG but also gave the car an additional 50hp once put back on the rolling road. I asked if a Terra clean would sort this but he said that does not go near the the inlet and exhaust valves and would need the head taking off to do.

Can anyone tell me a way of having these valves cleaned without taking the manifold off and doing manually please? He says that it will be approx 5hrs work??

As always thanks in advance for your help.

 

[RAG]

No probs.

The fault in mine was pretty unusual and only found comparing values from my car Vs another so I'd think it's an unlikely cause but the TB itself can cause problems which usually show up on VCDS.

I don't know if there is a manual method for doing an alignment but a good tuner ought to be able to sort it.

Hi Alex, I have just posted an update to this post and would appreciate your advice. Thanks

 

[S3Alex]

Hi Alex, I have just posted an update to this post and would appreciate your advice. Thanks

Unfortunately very common with all TFSi engines.
Terraclean won't do the job and it does mean getting the inlet manifold off.
The head doesn't need to come off and the exhaust valves are not affected.

The best way is to have it walnut blasted and it can be done for under £300.

Before.




After.




A few companies like AMD and Awesome can do this.


You can do it yourself and a few companies sell cleaning kits but it is a fair bit of work.

 

[RAG]

Thanks Alex, Ill look into getting the Walnut clean.

Do you know anyone in the sussex area that does the walnut blast clean?

 

[S3Alex]

Thanks Alex, Ill look into getting the Walnut clean.

Do you know anyone in the sussex area that does the walnut blast clean?

I'm afraid I don't.
I only know places like AMDTuning,which may not be too far from you.....

 

[RAG]

Cheers Alex,
I rang AMD and they said that it would need a total strip down of the head and Awsome said no strip down can be done from front of engine with manifold off but they do this manually not with walnut. I will look further into this but it does seem the inlet valves can be cleaned without the head coming off. Is that information correct?

 

[S3Alex]

Cheers Alex,
I rang AMD and they said that it would need a total strip down of the head and Awsome said no strip down can be done from front of engine with manifold off but they do this manually not with walnut. I will look further into this but it does seem the inlet valves can be cleaned without the head coming off. Is that information correct?

As far as I know,the head doesn't need to come off,and I'm pretty sure mine was done that way.
Don't quote me on it as the car has been in bits so many times anyway.....

 

[Cambaines]

I don't know how effective it is but I had mine hydrogen cleaned which is meant to clean your Inlet as they run it through your air inlet, how much it cleans it I really don't know, nothing like wallnut blasting though, black sh1t came out of my exhaust every time he revved it to clean it through mind

 

[XFi]

Clogged up inlet valves on a turbo car isn't as bad as a non turbo car like the R8. Sounds like you have a faulty MAF, have you tried unplugging it and seeing what you get? Either that or one of your lambda/O2 exhaust senors is broken and is causing massive over fueling.

I'm able to achieve 34mpg on my daily commute without trying, my engine has never been cleaned and the engines at 96k now so I do not feel like cleaning of the engine will resolve this. It will certainly go some way to help in terms of efficiency, power and delivery of power though.

 

[S3Alex]

Clogged up inlet valves on a turbo car isn't as bad as a non turbo car like the R8. Sounds like you have a faulty MAF, have you tried unplugging it and seeing what you get? Either that or one of your lambda/O2 exhaust senors is broken and is causing massive over fueling.

I'm able to achieve 34mpg on my daily commute without trying, my engine has never been cleaned and the engines at 96k now so I do not feel like cleaning of the engine will resolve this. It will certainly go some way to help in terms of efficiency, power and delivery of power though.

I'd dispute that a bit....the whole point of the valves is to admit air freely to the engine,with the least possible resistance.

When you start restricting that area with coking,irrespective of the engine being normally aspirated or turbocharged,you lose area,and thus restrict peak flow.
As you increase flow,with a remap for instance,that is exacerbated further.

 

[Boydie]

In my Stage2+ S3 I was constantly getting over 300 miles per tank with mixed driving

Now in my standard Scirocco R with Revo intake I am barely touching 300 miles since my driving is now more town focused

 

[Cambaines]

I get between 17-21 mpg all town driving, probably get 27-30 on a run, I don't drive stupid all of the time but it is nice to boot it! I've just got 180 miles out of my tank after a stage 2

 

[Boydie]

180 miles? that is horrendous! i would cry!

 

[Cambaines]

I usually can manage around 220 to be honest but I was driving a little heavy after the remap should come back into line a little now I hope

 

[S3Alex]

I usually can manage around 220 to be honest but I was driving a little heavy after the remap should come back into line a little now I hope

I can usually average 22mpg with a mixture of town and open roads,which means about 260 miles at the most,but obviously I do drive like your average gran...

 

[kash_v]

I get from half tank of vpower,before the light 90ish miles all town driving...Yet to actually do a long journey in it.

 

[XFi]

I'd dispute that a bit....the whole point of the valves is to admit air freely to the engine,with the least possible resistance.

When you start restricting that area with coking,irrespective of the engine being normally aspirated or turbocharged,you lose area,and thus restrict peak flow.
As you increase flow,with a remap for instance,that is exacerbated further.

Of course but a turbo'd car will feel the effects of this less due to it being forced induction and not relying on the engines ability to suck air into the chamber. I'm not saying it won't have an effect, I'm saying it wont have as much an effect. Either way if his valves were clogged to the extent that his MPG is that bad then I'd assume they would struggle to close fully and cause engine damage. I'm sure the engine would misfire badly as well before it was to get to that stage too.

Yes coking of valves will reduce power output, reduce efficiency thus reducing MPG but not to this kind of extent! I still believe this issue is most likely sensor related.

 

[t1evo]

180 miles? that is horrendous! i would cry!

I get 13-15mpg around 150miles out of the tank all local and very short journeys. Although I did once see 40mpg coming home one night on the A40 doing 50 slightly downhill!!

 

[Simply D]

all these 20+mpg figures are a myth!

im sure i was seeing 9mpg around town n possibly 16/17 on the motorway.

Was depressing me so much i just switched the display to show speed. thought that was just the cost of owning a S3 :s

I did have her checked over as she hunts sometimes when idling but nothing awry was found

 

[S3Alex]

all these 20+mpg figures are a myth!

im sure i was seeing 9mpg around town n possibly 16/17 on the motorway.

Was depressing me so much i just switched the display to show speed. thought that was just the cost of owning a S3 :s

I did have her checked over as she hunts sometimes when idling but nothing awry was found

If you're talking about short term figures then that would be partly true as I can easily get mine well below that.

What most of us are discussing is a longer term average,much more representative of overall figures and no,even on my car it's not a myth.

 

[Simply D]

If you're talking about short term figures then that would be partly true as I can easily get mine well below that.

What most of us are discussing is a longer term average,much more representative of overall figures and no,even on my car it's not a myth.

Then I must deffo have problems then

Even when non-hooning, the mpg figures on the dash were non-flattering.

Will need to do this oil cap test jazz when I get back n see how it responds