MPG Issues

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Westy_787

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Hi all,

First of all, this is my first post so go easy!

I've recently bought and 56 plate 2.0TFSI A3 with the BWA engine. Just over 70k on the clock and overall I'm very happy with the car. The previous owner has obviously looked after it just looking at the extensive service history with the car and the condition inside and out.

The car this replaced was my 60 plate E91 BMW 318D M sport plus, which unfortunately suffered a snapped timing chain due to the dreaded N47 engine being made out of chocolate. I would do almost daily 174 miles and would average approximately 45mpg ish.

I know the two cars obviously couldn't be anymore different, ones petrol and ones diesel. Ones an estate and ones a sportback ect ect, but having changed jobs I now only travel 20 miles to and from work so can enjoy a petrol again.

One thing I've noticed is very poor fuel mpg in the A3. My commute to work consists of one duel carrageway and one junction on the mway (approx 7 miles) Before I bought it I knew it would be bad. I was expecting minimum of around 20mpg with a bit of hard driving, but after a few weeks of steady, constant 'OAP' driving it really struggles to get to even 25mpg and that's at a push. Driving from Stoke to Preston, continuous 70mph saw a maximum of 30.1 mpg and that was for there and back when the motorway was dead. Reading fault codes there's nothing stored but once the engine gets warm it does start to run ever so slightly lumpy, which I know is quite normal for these engines.

Going off what I 'think' maybe causing it, the PCV valve and the fact It is due a fuel filter, spark plugs and air filter which I'll do this week, has anyone else experienced this? Thought I'd ask since someone maybe able to enlighten me. Obviously I'm not expecting 40+ at all under any circumstances but I was expecting to see early 30's I have to admit.

Thanks in advance
 
Id change, pcv, dv, spark plugs, oil filter/oil, fuel filter...it should run better.

However your mpg does sound about right.
 
I would do those things anyway but I wouldn't expect a huge improvement, my commute is 15 miles of motorway with a short section of junctions either end, I average around 27 mpg with it stuck at 70 with cruise control on, and usually even less on the way back (more inclines).
 
Run some BK44K cleaner through it and might clean the injectors a little.
I had a slight missfire on cylinder 3 when monitoring with VCDS, car also had a slight hesitation from 2.5-3k revs in 1st 2nd and 3rd from cold, this seems to have gone and the car now feels a bit smoother.
 
Cheers for the advise lads,

Given it a little run Saturday morning, around 25 miles each way with foot down a little more than normal and was reading 35mpg which was surprising. Did however seem to completely cut out for a period of maximum of two seconds though on the return journey home. No dash lights, headlights, power and radio off, read fault memory and no faults stored which is a little unusual. Anyway, Full major service carried out on Sunday Inc plugs and does seem to be smoother. Averaged 35mpg again on the commute to work so must be a little temperamental
 
I can still drag 20-24mpg out of my car,and that's a bit more powerful.

We had a serious problem with fuel consumption a while back,and I'd suggest checking all of the above,plus:

MAF
MAP sensor
Throttle body
Lambda probe
Thermostats

The engine will run with multiple faults across these(as mine did),and finally the throttle body was found to be faulty.
 
TFSI's have never been the best for mpg but changing the above mentioned items and a service (especially the air filter) should help. I've never heard of our petrol engines being lumpy though, that's a strange one. If you are going by the OBD mpg calculation, don't. Do another mpg test by filling the tank a couple of times, keeping note of litres used and distance covered.
 
Quick update, it would something has failed in my opinion just a case of what really. Seems to be getting better and better the more I drive, it seems to be averaging between 26/29mpg (on dash) steady, it's reading 31+ majority of the time I have to admit. Even saw 39.8mpg this morning again on dash. However, even accelerate up 10mph to overtake for example and it shoots all the way down to 20/22mpg almost instantly. Taking forever to get back up to even 25mpg. Going to start replacing some of the above mentioned and see if it improves. Unusual that no faults are stored and reading measured values, everything seems correct. But thanks again for the advise, I'll update again once I've replaced a few components.
Ps, turns out running ever so slightly due to flywheel failing. Failed this weekend, when accelerating, get a juddering/squeak underload. Just my luck ha
 
From a tank my s3 gives me 260 miles, thats half driving town and the rest motorway at the weekends.

If it was all motorway/dual carriage way i reckon id get round 300.

I dont really drive it hard, often feathering the throttle unless a 120d feels the need to inspect my rear bumper.
 
kash_v said:
From a tank my s3 gives me 260 miles, thats half driving town and the rest motorway at the weekends.

If it was all motorway/dual carriage way i reckon id get round 300.

I dont really drive it hard, often feathering the throttle unless a 120d feels the need to inspect my rear bumper.
Click to expand...

Going to start doing my own mpg calculations between each full tank but that does sound something similar if not a little less. Do love the element of surprise though, having an unexpected 200bhp when said Bmw gets too close.
 
I have a BWA 55 Reg 2.0 TFSI and average 23MPG for city driving. A real ️ hog!


Sent from my iPhone using Tapatalk
 
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Thought I would re-open this thread as I am having the similar issues, however my MPG stays low all the time. Im getting about 200 miles per tank on a 2.0 TFSI.

So far Ive changed the following: PCV, DV, Thermostat, Coolant Sensor. I've also had a full service with oil and fuel filters changed. I am going to look at my air filter today to see what state its in and replace it as well. I am slowly running out of idea's and not really keen to throw more money at the problem.
 
Nanz said:
Thought I would re-open this thread as I am having the similar issues, however my MPG stays low all the time. Im getting about 200 miles per tank on a 2.0 TFSI.

So far Ive changed the following: PCV, DV, Thermostat, Coolant Sensor. I've also had a full service with oil and fuel filters changed. I am going to look at my air filter today to see what state its in and replace it as well. I am slowly running out of idea's and not really keen to throw more money at the problem.
Click to expand...
When were your spark plugs last changed?
 
200 miles! I get more out of my 3.2. Not much more though.

it’s not had a dodgy map in the past has it?
 
danrst171 said:
When were your spark plugs last changed?
Click to expand...
Had them changed in the last service I did back in August 2020.

I am going to check them this week however, just waiting for the socket to turn up.
 
abmat said:
200 miles! I get more out of my 3.2. Not much more though.

it’s not had a dodgy map in the past has it?
Click to expand...

Not its bog standard out of the factory. The car has only done 50,000 miles. This all started happening after I had the air-con compressor changed at a garage local to me. The guys then had no idea how to diagnose the issue let alone try to sort it so I stopped going there and I've just taken it upon myself to try and sort this myself with the help of another mechanic I've found.
 
abmat said:
What colour were the plugs last time?
Click to expand...
Too be honest I don't know, I didn't see them as the mechanic did it in the service. He did say they were not great quality and replaced them with NGK plugs.
 
So I cleaned the MAF sensor this morning and this seems to have sorted my problems. Went for a good long drive and am now getting 25+ MPG local driving and 34+ MPG on the motorway.

I'm gutted I didn't think of doing this months ago.
 
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