Very Poor MPG

[yossarian247]

52 minutes ago, Cooket3 said:

Completed the next calculation and I have done 35.19 mpg, still  rubbish. my cars computer says 27.7mpg and was reset when i topped up the tank, my mind boggles to how the trip computer is way out, 1 or 2 mpg yes but not 8!

I have known worse, the fuel computer on my old Xsara HDi used to show 35 Mpg when it was actually getting 50+ Mpg!

 

 

[lilpopjim]

I had my engine swapped with another 2AD-FHV engine from another Auris as my original had a head gasket leak. I bought a crashed SR180 and swapped it over. Engine is good but since i've got this new engine in i've been getting poor mpg. I used to get about 400-420 miles to a tank.

I done a journey from Hertfordshire up to Birmingham to get a supercharger for my dads MR2 then down to Hastings and back up to Hertfordshire. Computer said average of 44 but i think it was actually 39 when i figured it out. this was 80-90mph most of the way as the roads were clear as anything.

I've almost finished my first full tank on this other engine and i'm getting 31mpg average (i haven't emptied it so can't calculate!) as per the computer.Even cruising at 70 will yield 32mpg... Terrible!

The engine came from an ex demo Toyota SR180 so was likely driven slow for its life. The EGR was almost completely blocked so i gave it a good clear couple weeks ago. I'm thinking about cleaning the whole intake manifold at some point to be honest as obviously all the exhaust gases flow into the manifold, so there's going to be a huge buildup of carbon so will decoke that at some point. Hopefully this fixes improves this **** mpg.

I'm also thinking about getting a chip for the car as well. Power is okay but feels slow after owning it for a year and a bit. Still beats most cars but eh... more power! My dad says the same about his toy car, this is why he's getting his MR2 MK3 Roadster Rotrexed to give him 340bhp!

 

Edit: Also, now that i think of it, i used to get better mpg on my Toyota Corolla T-Sport and that had a 1.8L 192bhp engine! saying that i was forced to cruise at 70 because of the noise (was at like 3.8K 70MPH). Then again that engine had two sets of Cams. A low speed cam so i basically acted like any other 1.8 and a high speed cam which gave it i think 50 extra horses to get to 192bhp. Would suck fuel once it got to it's 8.2K redline though .

I remember getting 42.5mpg on a run at some point!

 

[DAF XF]

Mines is 2.0 126hp but my experience from brimming tank right to top that my trip computer underestimates real fuel economy by usually 2mpg. So if it says 46 I've actually got 48. 

Mine was already well broke in when I got it with 60,000 something on it. Highest ever achieved was 55mpg but never replicated it and it was driving at 50 or just below and taking more care accelerating slowly and braking slowly etc. The old one about imagining the accelerator having an egg underneath it so you didn't want to push too far in case it cracks!

worst is probably 42 or 43 roughly and 47/48ish is standard mpg I seem to get . I notice unlike any other diesel I've had before it it really doesn't like cold weather and there's not that huge a gain to be made by driving a lot more economically. I'm going to carry out the egr valve clean on mine as its now done over 150.000 and never been looked at as far as I'm aware and it gets a lot of supermarket fuel. 

Been keeping more records since Feb as I downloaded an app so have probably subconsciously been more economical in my driving!

Last few fills:

feb fill 1- real 49.98mpg       trip 48.2mpg    From 480miles

Feb fill 2 - real 51.81mpg     Trip 49.5mpg    From 557miles

feb fill 3 - real 47.11mpg      Trip 45.7mpg    From 495miles

feb fill 4 - real 49.40mpg       Trip 47.4mpg   From 474miles

mar fill 1 - real 48.66mpg      Trip 47.0mpg   From 511miles

 

 

[lilpopjim]

I've only had my car for about 10K miles. Mpg has always been 38-40 or there abouts but since swapping the engine with one which hasn't got a head gasket problem I've been getting about 32mpg.

To be honest I haven't been doing a whole lot of long journeys recently but like others I get decent mpg cruising at 40/50 (obviously) but as soon as I hit the motorway it drops drastically to 28-32. Ive noticed that it will go to 40 or so then will drop down to low 30/ high 20 then back up to 40. I'm thinking 5th injector issues but surely it can't be going off all the time.. 

Sometimes when cruising you get the smoke and the burning smell which is the DPF regeneration but it doesn't last long. 

I miss my very first car. I had a Vauxhal Corsa 1.3CDTi  which constantly got 55-60mpg regardless if I thrashed it or drove economically. I got 65-70 at one point when I drove as economically as I could. 

[Countrylad]

My 1.6 petrol Touring gets around 37 mpg in daily use, but it rises to 41-44 on long journeys, and I once saw the figure briefly hit 46. Doesn't compare with a hybrid or a diesel, but it's a simpler engine set-up and I'm all in favour of that because there's less to go wrong.

Recently the average mpg on the dash dropped to 33 or thereabouts, but after a good thrash on the motorway it was back up to 38 and has stayed there since. I think there might be a moral there somewhere. Italian tune-ups work.

[lilpopjim]

Italian tune ups do work!

My sister drivers her Ford Fiesta  like a diesel.. changes gear at like 1800rpm  in a 1.25 petrol and she's constantly lugging  the engine..

She's selling it now but the engine ran like apsolute crap. Misfires on idle and if you went past 50% throttle the car would start to die and missed a lot. You'd start to slowdown xD 

I got hold if it and redlind it everywhere (once it got to redline at 40% throttle or so :P ) for a good 15-20 minutes once it got to temperature. 

Car was apsolute fine after that!

[Cooket3]

Just done a total of over 5 hours on the motorway! 90% was motorway driving and I manages a whopping 41mpg! Alot better but not amazing but this figure seems in line with other forumites, oh and my trip computer still said 27.9mpg!!

[lilpopjim]

Ha! What the hell is up with the trip computer then.. When i'm on the motorway it will read low 30's when cruising at 70. anything above that and it drops to high 20's like yours! Stupid thing.

By the way how was the tuning box? How much better (or worse) was the engine after that?

[Cooket3]

I have no  idea! I have reset trip on both A and B before my journey and both are the same, the only other conclusion is that the last owner srive for 5 minutes ever day in a city and my computer has remembered that but wont start from fresh?? Also it says a full tank of diesel will get me 296miles!! WTF after 150miles 2 bars are gone and says i got around about 150 left to go, then it thinks "oh there something wrong here" and calculates 1 mile as 2 (I do 2 miles to 1 thats left in the tank) and every fuel bar that goes down 1 bar = less miles e.g. 1 bar = 80, 2=50, 3=40, 4=30 5=30 etc 8=20 and i darent find out what bar 9 is!

[Cooket3]

Just experimenting on my motorway journet. According to my average mpg I was getting 60+ on the motorway in 4th gear doing over 60mph, when in 5th and 6th I get way less. Somethings not right, could it be something to do with the engine etc before the turbo kicks in?

[lilpopjim]

Didn't realise you replied before! 

The fuel gauge is just an instrument that's supposed to be used as a guide not as an accurate fuel level indicator. Remember that the tank isn't just a box, it's shaped to fit the car under the rear seats so it's got dimples and shapes punched out for strength and what-not.

It's accurate for the most part, it tells you when its full and tells you when it's empty which is all i need as far as i'm concerned 

 

That's funny, maybe you should put a fiver in the tank and just do pure motorway miles in 4th and see what you get. The engines peak torque is around 2K/2.2K rpm which is of course when the turbo is at full boost. I'm not an expert lol but i'd expect motorway driving would be most comfortable for the engine at this rpm. I know it wont be at full boost at this rpm when you're cruising but maybe the fuel map is different at this rpm while cruising?? I don't know..

It's also worth taking note that i've got 40 miles remaining on my car with 360 miles on the clock!! knowing the trip computer, like yours it's !Removed! stupid so i'm expecting to get 430 miles out this tank.. Amazing really seeing as i've been driving to the gym every morning which is a 4 miles drive.. engine only gets up one or two bars on the temp.. Amongst other journeys which have been around town and that kinda thing. I'm impressed :D I was driving it nicely for the first 200 miles but i've been driving it spiritedly on the last 150 miles. Mainly hard acceleration to get up to speed before just cruising in the highest gear.

[Cooket3]

O know the fuel guage is just for show and info, but its just soooooooo wrong thats what really annoys me and the mpg calculation is completely wrong too. If it was accurate I can cope better with the poor mpg etc

Putting a fiver in the tank wont achieve anything its impossible to read accurately, the only proper way is to brim the tank and drive then re brim. Im filling up today and will only drive in 1st to 4th this time to see what i get after a week then re fill.

Short journeys are really bad for my car as even 15 min drives plummet my mpg.

I didnt have the chip on the car for the motorway trip or months before, I was running on the cars own programmine. I can only dream of 430miles on a tank, as you can see from my post i drove for 5 hour trip on a motorway and still got less than that

[FROSTYBALLS]

6 minutes ago, Cooket3 said:

Putting a fiver in the tank wont achieve anything its impossible to read accurately, the only proper way is to brim the tank and drive then re brim.

Putting less than 15 litres of fuel in when filling up can itself give erroneous readings as regards range, fuel consumption, etc.

[lilpopjim]

Fuel gauges have always been weird in Toyota and Lexus cars. It's a little frustrating but you get used to it! Getting 120 miles on the first bar makes me believe I'm getting sublime mpg  figures but then it drops 2 bars in the next 5 miles haha.

The mpg computers can be so far off though! Some tea they're accurate sometimes they're 10mpg off as I've found.

Also I got 415 put the tank when it hit 0 on the range, thought it was time to fill up after that! It's funny though as like I said, I've been doing so many short journeys last couple weeks. 200 mlies on the motorway cpupled with short journeys gave me 340 to the tank. Thats worsee than my old corolla with 190hp..

When i cleared the EGR out when i got the car i noticed an increase in MPG as well as the car being more happy when cold and more responsive. When I get time in the summer I plan to remove the intake manifold and decoke that and see what difference it makes. Not before I've used my dad's snap on  endoscope though.

[Cooket3]

I filled my car up from zero (3 litres left in the tank) and the computer said i could get 394 on a tank now when its always been 100 less! This car gets worse mpg than my old petrol 240bhp leon.

There has to be something wrong as on the motorway i got 41mpg. My egr was cleaned last month but i have now noticed that there is little power less than 2k rpm then full boost kicks in throwing you back into the chair. The other day when i pulled off (was a really hot day) I had virtually no power in 1st and second to 2.5k rpm then full power after that, there is no smooth transition at all

[Cooket3]

Just had a P0087 error, rail pressure error, sounds expensive! :-(

[lilpopjim]

Oh no, sounds like it's related to the problem you were having the other day.

Hopefully it's just a fuel pressure regulator. Normally found on the end of the common rail; normally around £50 i think. 

Do you think it could be your fuel pump?

Edit: Also check/ replace your fuel filter if you haven't in a few years! I know diesel filters can be neglected and just plain forgotten about until the water light comes on. Friends car was a little lumpy when being floored a couple years ago.. Fuel filter was as black as anything. Replaced it and it ran absolutely fine.

[Cooket3]

Im hoping its due to the chip being turned too high. Going to disconnect after work and re try.

I have no idea if it could be the pump as i am not technical when it comes to cars. Fuel filter was replaced a few months ago when it was serviced

[lilpopjim]

Ah right didn't realise you had that chip still on. How is that anyway? I'm thinking of getting the Lindop one soon.

I've got a second SR180 which I'll be breaking soon so if you need any parts let me know.

[Cooket3]

The chip only went back on a while ago after other testing of the car. The chip is removed and the error doesnt happen anymore , put chip back on and turned it to zero and works fine, I must have had it turned too high.

I think it does improve performance but not mpg at all, maybe something else wrong with my car as ive noticed it now sometimes struggles to start. Ive been told it may be a pressure think in the rail. I remembered to record it on camera one day! the day before it was twice as bad

20170419_170432.mp4

[lilpopjim]

Glad you figured it out. How much better is the car with the chip? Is there a big difference in low down torque? I'm still pulling hairs on whether to get a chip or not. 

Well you either have MPG or power they don't really go hand in hand!

Sounds like it's diesel knock though its hard to tell as it doesn't last long till the engine idles fine. Possibly due to the increased fuel rail pressure from the chip so its over fueling on startup until it idles. What do you think? Try it with and without the chip.

 

[Gathelios]

Just a quick thought on why the computer's MPG is off, the maximum it shows is 99.9 on the current view. So if you coast a lot I wonder if that's the maximum it's able to calculate from for the average.

In reality, putting the clutch in and rolling down a hill will give you far more MPG than 99.9, but if the car only recognises that 99.9 the averages are negatively skewed.

I used to have a Skoda that measured up to 999.9, it was a lot more accurate when going brim to brim.

I've also been thinking about a Lindop chip for a long time now, let me know your thoughts!

 

Sent from my iPhone using Tapatalk

[lilpopjim]

That's possibly true. My mpg figure is either correct or it's completely off.. I find that motorway journeys yield a more accurate figure compared to short journeys. Short journeys apparently gives me 32 mpg but I know for a fact it's a lot more than that :P

Well the Lindop was partly developed by Toyota as far as I know by the boys up north. (am i right?) It's probably the best way to increase the power of the engine safely. I know Bluespark do those tuning boxes that increase boost/ fuel pressure just like the Lindop one but those  boxes are also universal units, not "custom" for the 2AD-FHV lumps in our cars.

Increasing boost and fuel is your best bet. Getting those cheap Bluespark ones only dump more fuel into the engine. Not all the fuel will be burnt up (more than likely) so i can image your EGR/ intake manifold will cake up faster than normal along with extra soot in the DPF potentially blocking that up along with more frequent regen cycles..

I'll just get the Lindop 

[Cooket3]

The chip does work, I think it is more powerful but cant really tell you by how much unless i do a few drag races or put it on a rolling road! Mpg is supposed to increase as more torque is generated and therefore need less throttle to pull away, im lead to believe, but my car must have problems to get utter bs mpg etc.

[Cooket3]

chip is off and still doesnt start good somedays like my above vid. Any ideas?