[Johnnybhoy7]

For about the tenth time in here to rattle the experts brains about my low mpg. To summarise the story...
Car wasn't getting up to temp - stats replaced
Warped disc was catching - brakes replaced

Thought these had solved my issues of low mpg but they're back.

Car sailed the mot last week so I know it's no issues with braking department which leaves me to believe that it's the injectors.

I don't have any fuel related fault codes so what I would like to know is how can I diagnose it? What are other signs or worn injectors.

I get a strong smell of diesel on idling so thought could be seals but visually I can't see or hear any fuel leaking.

I've obviously taken into consideration the temperature and the effects of winter fuel but my mpg is considerably lower than previous winters as I've had the car 3 years.

Not doing many miles ATM only about 40 a week but only returning about 20 and 37 on longer runs

Thanks again for the help

[pmmcbl]

What engine is this? But doing 40 miles a week don't expect big returns especially if you are doing them around town.

[Johnnybhoy7]

Originally Posted by pmmcbl

What engine is this? But doing 40 miles a week don't expect big returns especially if you are doing them around town.

M47 320d. Wasn't expecting big miles from short journeys. As I said I'm even getting low mileage on long journeys. Done 120 mile round trip basically driving like a gran. Wasn't cold was a mild day. Car was well heat up. Only returned 37. Shite basically haha but even the short journeys should be getting more. Got more driving to work in forged Astra vxr

[Digitalize]

Look at things like EGR, Swirl Flaps, MAF, air filter, oil etc. And to a lesser extent even glow plugs.

[Johnnybhoy7]

Originally Posted by Digitalize

Look at things like EGR, Swirl Flaps, MAF, air filter, oil etc. And to a lesser extent even glow plugs.

Egr was terracleaned 6 months ago. Unplugged maf and still ran the same does that mean it's working or not? Swirl flap are done. Glow plugs replaced and the control unit. Air filter gets cleaned every August along with an oil change. I really don't know what else it could be haha

[Pumper]

You are not alone.

I had all glow plugs changed, both thermostats changed, new bosch MAF installed, low mile 2014 lambda sensor installed, etc. and still suffer form crap MPG (with 205/55R16 tyres). My average sits at arround 36-38 with at least 50% highway. During the coldest two weeks (-15C and more) driving arround town it retured 19mpg.

Got myself a can of Liqui Moly diesel aditive as a last resort. If that won't clean up the system (if there's an issue with injectors) I won't invest any more money trying to solve the problem as it will never pay off in fuel savings.

The last thing I might do to the car is a DPF removal/delete with a remap. That's a ~230€ investment over here.

[djgandy]

Is your MPG computer measured or tank to tank?

[Johnnybhoy7]

Originally Posted by djgandy

Is your MPG computer measured or tank to tank?

measure and from OBC as its been calibrated

[borinous]

what are your expectations for MPG? if i recall yours isnt remapped or anything?

i have no idea what mine does around town. my OBC is at about 44.1 i generally dont re-set it and i did a trip to cornwall from essex and even though the needle didnt really budge from above 50mpg the average only went up to 44.8. mine is remapped with a generic map.

i would test the accuracy of the OBC using a MPG app where you input the amount of fuel and mileage etc. see if it tallys up.

sounds like your car is in top shape only other things could be low tyre pressures, running big fat tyres, having 2 15" subs in the boot? driving with the window open or air con on (which given your location i suspect is un-likely)

it could be over fueling if something gone screwy with the FPR? do you get alot of soot out the back.

Boost leak?? check all your air ducting for splits or cracks.

[Johnnybhoy7]

Originally Posted by borinous

what are your expectations for MPG? if i recall yours isnt remapped or anything?

i have no idea what mine does around town. my OBC is at about 44.1 i generally dont re-set it and i did a trip to cornwall from essex and even though the needle didnt really budge from above 50mpg the average only went up to 44.8. mine is remapped with a generic map.

i would test the accuracy of the OBC using a MPG app where you input the amount of fuel and mileage etc. see if it tallys up.

sounds like your car is in top shape only other things could be low tyre pressures, running big fat tyres, having 2 15" subs in the boot? driving with the window open or air con on (which given your location i suspect is un-likely)

it could be over fueling if something gone screwy with the FPR? do you get alot of soot out the back.

Boost leak?? check all your air ducting for splits or cracks.

It's not mapped no. I'd say reasonable about town would be 30. I'd be happy with anything over that. If it was only the short journeys I was getting low mpg I wouldn't care as I'd know that was the cause. But it's the fact the long journeys the mpg is shit too which makes me think something's wrong. No black suit what so ever. I get a puff of white smoke when the car starts which everyone says is the plugs and module. They're 2 months old plus there's no fault codes stored. I had a listen to boost leaks and can't hear anything plus the car still pulls very well. Tyres are only 265/30/19 on the rear. No subs. No windows down or air con - Baltic here lol ive calibrated the OBC mileage so I know that's pretty accurate but I did do calculations the old fashioned way too and again it was very low. It's not costing me a lot of money as I'm not doing the miles I use to but it's just really annoying me. I like my car to be as perfect as I can get it haha

[Aragorn30d]

how short are your short trips?

If i reset the OBC and drive to the local shops or macdonalds a few times, it'll be in the low 20's.

It'll do 30+ about town, but only if the engines actually reaching operating temp. It takes about 5 miles to get up to temp normally, so any trip shorter than this will have awful consumption.

[vladmury]

I noticed when temp drops below 7 degrees the mpg is down also by 8-10 mpg. In the sunmer, 320d 163 auto I get easily 50 mpg cruising at 130 kmh.

Check MAF , water temp, injectors values in Inpa and DPF if its clogged.

[Johnnybhoy7]

Originally Posted by Aragorn30d

how short are your short trips?

If i reset the OBC and drive to the local shops or macdonalds a few times, it'll be in the low 20's.

It'll do 30+ about town, but only if the engines actually reaching operating temp. It takes about 5 miles to get up to temp normally, so any trip shorter than this will have awful consumption.

If I reset mines and drive to work, it's very short you're lucky if it's 3 miles I'd be very lucky to get over 17 lol when up to temp driving about town I get about 25. I know it's not terribly low it's just annoying. I can live with the low mpg to work as I expect that but it's the longer journeys I only get 37 that annoys me most.

Originally Posted by vladmury

I noticed when temp drops below 7 degrees the mpg is down also by 8-10 mpg. In the sunmer, 320d 163 auto I get easily 50 mpg cruising at 130 kmh.

Check MAF , water temp, injectors values in Inpa and DPF if its clogged.

Yeah I know when it gets colder it drastically effects the mpg but this time last year I was getting 34 mpg.

I unplugged the maf for a while and seen no improvements so not that
Car does get up to temperature pretty quickly
Don't have a dpf
Need to look the INPA values try find a local who can use it and tell me what the numbers mean

[vladmury]

Well if by dissconecting the MAF you see no improvements doesnt that mean if the MAF was good car will drive worse with maf unplugged?

[borinous]

37mpg on longer journeys does sound low. but if that journey is at cold ambient temp maybe thats normal? seems there is a theme appearing where people are saying when its cold outside the MPG suffers.

also noted you mentioned driving like a gran....sometimes thats not the most efficient mode to be in to conserve fuel. you may find that cruising on a motorway at "gran" speed of 55mph is actually making the car sit in a high fuel usage rev range. when sitting at 70/75mph puts you in a leaner band therefore using less fuel?

I did a trip to disneyland paris on a single tank of diesel so 60 litres i did 600miles which works out to be ~45mpg so if thats scaled down to a shorter 100mile journey 37pmg doesnt sound unfeasible

[Aragorn30d]

it depends on the journey and how your defining "long". To some people 10miles is a longer trip, but the reality is thats still pretty short.

My brothers 320d would struggle to get 40mpg on what he considered a decent non-town journey, namely his drive to work. Its perhaps 10miles, of A-road with a 50 limit. But its also full of junctions and traffic lights, and being a diesel, its doing half that distance before its fully warmed up.

Take the same car on a 300mile motorway run to england sitting at sensible speeds on cruise control, and it will manage about 50mpg.

[Pumper]

Originally Posted by Aragorn30d

Take the same car on a 300mile motorway run to england sitting at sensible speeds on cruise control, and it will manage about 50mpg.

That's the problem with some of our 320ds. I never even see an instant consumption of 50, let alone average (even after a cruising trip of 150 miles with average speed of ~65-70 mph I only get 42mpg or less - I bet that Johnny has the same issue).

[Aragorn30d]

instant consumption is kinda missleading, because your very rarely in a constant state on a perfectly flat road. Uphill you might be down in the 30's, but coming down the other side you'll be up in the 60s or 70's

[Johnnybhoy7]

Originally Posted by Aragorn30d

instant consumption is kinda missleading, because your very rarely in a constant state on a perfectly flat road. Uphill you might be down in the 30's, but coming down the other side you'll be up in the 60s or 70's

My drive home from work at night is only about 2 miles. If I reset it on my way home, one hill to drive up I only get 17mpg by the time I'm home it's awfully low haha the 'long journey' I done was about 170 miles all in. Was basically west coast to east coast and back. I was sat at 60 on the m8 mostly on cruise control. By driving like a granny for me that means not my usually harsh accelerating haha

[Aragorn30d]

yeh i think with such short journeys its never going to be great. would have expected a bit more driving across country though.

[vladmury]

Denmark -Romania and back (4000 km) I got 5,6l / 100 km (50 mpg) driving most of the time with 140 kmh . 320d 163 auto 318 000 km :-) with 205/55/16 dunlop blue response

[Johnnybhoy7]

Originally Posted by Aragorn30d

yeh i think with such short journeys its never going to be great. would have expected a bit more driving across country though.

Yeah I know the short journeys are gonna be a killer but I'm only getting half what I was getting this time last year. It's bugging me and should have defo got more over the longer journey I feel. It surely has to be maf egr or injectors?

Maf and egr should be fine I think but gonna give them a wee clean see how I get on. If that fails just gonna send it into a garage