1.4 MPi: 24.5mpg, WTF

JohnAA · 30-12-2007, 10:34

Just refilled it brim to brim after 235 miles. £45

At these prices, it can't even return 25mpg, that is what I get from the Supra during 'mild' motorway driving.
Not

The tyre pressures are OK (were 5-10psi down when I bought the car)
What else should I check in order of importance now?
My guess is to change the spark plugs.
Air filter appears to have been recently changed in the service history. Is the fuel filter an issue with these cars?
Anything else I may have missed? Fluid levels are all fine. It's got to be something obviously wrong here...

Edit: just checked the service history printouts and it had new plugs (BKUR5ET) 3K miles ago.
So what on earth could force mpg to be so low!?

djswivel · 30-12-2007, 11:05

If you've done a lot of milage, the cat may have gone.

Or it could be the lambda sensor - this really buggers up emissions.

corradoboy · 30-12-2007, 11:08

I've always found small petrol engined cars to be uneconomical. Had a 1.2 Corsa for seven months whilst I was training as a driving instructor and that never managed better than mid 20's. My old Impreza could average 33 if you drove like the pope's chauffeur. The problem is, for me anyway, that as there is virtually no power whatsoever you spend a lot of time with your foot flat to the floor, which forces a lot of fuel through an engine that can't do much with it. I also think small engines are unsafe, as often in dangerous situations the best course of action might be to boot it and get clear, and if your car can't do that then you're gonna get it. That's why I now teach in a vRS. I recently had it in for some repairs and had a Corsa diesel for a couple of days and all the learners commented on how pathetic it was to drive, having got used to the oomph

Small engines = false economy based on another eco-mentalist green lie.

JohnAA · 30-12-2007, 11:12

Lambda sensor, good point.

Why didn't I think of it, what's wrong with me?

Is it accessible guys, is it a fairly universal type (i.e. cheap?)

Cheers

rum4mo · 30-12-2007, 12:08

Quote:

Originally Posted by corradoboy

I've always found small petrol engined cars to be uneconomical. Had a 1.2 Corsa for seven months whilst I was training as a driving instructor and that never managed better than mid 20's. My old Impreza could average 33 if you drove like the pope's chauffeur. The problem is, for me anyway, that as there is virtually no power whatsoever you spend a lot of time with your foot flat to the floor, which forces a lot of fuel through an engine that can't do much with it. I also think small engines are unsafe, as often in dangerous situations the best course of action might be to boot it and get clear, and if your car can't do that then you're gonna get it. That's why I now teach in a vRS. I recently had it in for some repairs and had a Corsa diesel for a couple of days and all the learners commented on how pathetic it was to drive, having got used to the oomph

Small engines = false economy based on another eco-mentalist green lie.

Yes how very true, once when travelling South on M6, and in heavy fast(sh) traffic, driving my CAV GSI 2000 4X4, I suddenly spotted that the roof rack full of bikes, mounted on the car ahead and in the centre lane, was sliding sideways - to RHS of the car, I booted it as I didn't want to get involved with the aftermath of that. Just made it along side as the rack came down the side of the car - it missed me but a pug 205 picked it up and I'm sure it wrecked at least his radiator - don't know if anyone ran into the back of him. You don't that when you still have about a 1000 miles to go!

rum4mo · 30-12-2007, 12:12

Quote:

Originally Posted by JohnAA

Lambda sensor, good point.

Why didn't I think of it, what's wrong with me?

Is it accessible guys, is it a fairly universal type (i.e. cheap?)
Cheers

Really this car needs checking professionally as just changing sensors is very expensive and guessing. If you want a cheaper "guess" I would have a go at changing the engine temperature sensor - the one the ECU uses - if it does use one with this engine. Buy a Haynes book to guide you if you are thinking about sorting your own car - might have to order it though.

redbaron · 30-12-2007, 12:13

you should easily be getting 35+ and into the 40's on a longer run...

lambda sensor is worth a check.. reset the ecu (batt off for 10 mins should do it...)

would also try some injector cleaner in case one is sticking?

have you tried giving it a damn good thrashing ?

one odd thought some hero hasnt tried uprating the fuel pressure regulator have they? this would explain the economy as it will be running richer than dodgy labour party donator......

JohnAA · 30-12-2007, 12:23

Quote:

Originally Posted by redbaron

you should easily be getting 35+ and into the 40's on a longer run...

That's what I thought, worst case 35 if there is a heavier element of start-stop traffic.
Previously I had a battered Astra diesel as a runaround, low-pressure turbo (no pressure more like it) and despite it's sorry state (and mileage) it would still return 40mpg. The head wasn't even crossflow FFS...

Quote:

lambda sensor is worth a check.. reset the ecu (batt off for 10 mins should do it...)

I'll do that definately after any major component change. If it was in limp-mode there would be an ECU light though, wouldn't there?

Quote:

would also try some injector cleaner in case one is sticking?

That would be my next step, use some STP total system cleaner (the only one (out of two) that actually works in my experience)

Quote:

have you tried giving it a damn good thrashing ?

I'll grab a tree branch and get started

Quote:

one odd thought some hero hasnt tried uprating the fuel pressure regulator have they? this would explain the economy as it will be running richer than dodgy labour party donator......

Nah, it was owned by the same fellar from new, and I get the impression he wasn't young either. There is no evidence of 'boyracer' interventions anywhere.

What I don't understand is this: Failing sensors would be flashing warning lights, wouldn't they? Hmmm....

oilburninnut · 30-12-2007, 12:40

Quote:

Originally Posted by corradoboy

I've always found small petrol engined cars to be uneconomical. Had a 1.2 Corsa for seven months whilst I was training as a driving instructor and that never managed better than mid 20's. My old Impreza could average 33 if you drove like the pope's chauffeur. The problem is, for me anyway, that as there is virtually no power whatsoever you spend a lot of time with your foot flat to the floor, which forces a lot of fuel through an engine that can't do much with it. I also think small engines are unsafe, as often in dangerous situations the best course of action might be to boot it and get clear, and if your car can't do that then you're gonna get it. That's why I now teach in a vRS. I recently had it in for some repairs and had a Corsa diesel for a couple of days and all the learners commented on how pathetic it was to drive, having got used to the oomph

Small engines = false economy based on another eco-mentalist green lie.

i agree the wifes 1.3 swift is not in anyway economical,it is quite powerful for a 1.3 at 90bhp,but only returns 35ish mpg's,and it never gets driven like she stole it,i was kind of hoping when it loosens up a little it may improve(only done 2000 miles)on a long run we were strugling for 50mpg's,which my fabia would have done easy,and faster

ric04vrs · 30-12-2007, 12:58

i'm sure a faulty Lambda sensor would throw the engine warning lamp on

Reece_1 · 30-12-2007, 13:47

Quote:

Originally Posted by corradoboy

I've always found small petrol engined cars to be uneconomical. Had a 1.2 Corsa for seven months whilst I was training as a driving instructor and that never managed better than mid 20's. My old Impreza could average 33 if you drove like the pope's chauffeur. The problem is, for me anyway, that as there is virtually no power whatsoever you spend a lot of time with your foot flat to the floor, which forces a lot of fuel through an engine that can't do much with it. I also think small engines are unsafe, as often in dangerous situations the best course of action might be to boot it and get clear, and if your car can't do that then you're gonna get it. That's why I now teach in a vRS. I recently had it in for some repairs and had a Corsa diesel for a couple of days and all the learners commented on how pathetic it was to drive, having got used to the oomph

Small engines = false economy based on another eco-mentalist green lie.

Always had engines in the 1.2 range and never had any problems regarding both with performance and economy. However do find 1.0 litre engines tend to a be a bit heavier in terms of fuel consumption - had a Kia Picanto 1.0 last year as a hire care the mpg wasnt a brillant as expected. My own Fabia 1.2 returns average mpg well into the 50s, and on a nice long run with no stop/starts and right conditions goes into the 60s.

I dont drive slow and then I dont drive like a stress monkey.

Duggie · 30-12-2007, 15:00

My 1.4 MPi Returns around 25mpg... my mate has a M3 and it does better than that!! However, when I do drive economically i can get the actual MPG rating on the dispaly to hit 50-55 ish, the combined rating never gets that high though! Please let me know what happens with yours!!

smstext · 30-12-2007, 15:09

have you had it checked with a vag com? might point at sometihng thats wrong. other than that has the car done alot of small 5 mins start/stop runs?

I personally would but redex injector cleaner in and go for a very good boot in it and flush the system through and see how it goes after that.

ScoobyChris · 30-12-2007, 15:42

Quote:

Originally Posted by Reece_1

Always had engines in the 1.2 range and never had any problems regarding both with performance and economy.

Agree with this - my old Micras used to return 50+mpg no matter how much they were abused and the Corsa 1.2 would easily get 40+mpg, but was an 8v unit rather than the newer 16v one.

Definitely recommend a diagnostic fault scan as that might highlight something simple which has been overlooked. It might also be worth giving the car an Italian tune-up as that seems to work wonders in clearing up faults

Chris

JohnAA · 30-12-2007, 15:52

What's the italian tune-up guys?

Tom_vRS · 30-12-2007, 17:30

Thrash it!!! Get the engine nice and hot, a good 10 miles in 3rd gear at 60mph would do it.

JohnAA · 30-12-2007, 18:21

Quote:

Originally Posted by Tom_vRS

Thrash it!!! Get the engine nice and hot, a good 10 miles in 3rd gear at 60mph would do it.

So you think it might be carbon deposits inside then?

It is not inconceivable, the car has done 85K miles probably in urban conditions.
The STP cleaner will make a vast improvement if that is the case - I'll have to wait until the tank is half empty though, at £15 a go I'd like to get good value out of it.

Tomorrow I'll take out the spark plugs and check condition

and gaps (Haynes says it should be 0.8mm). If temp or oxygen sensor is faulty they should be very black.
I'll also do a compression test just in case, it won't hurt I guess. Won't bother with leakdown test, since I'm not going to open the engine anyway.

Intriguing

...

kwacka · 30-12-2007, 18:34

checked for binding brakes??

Chrispy · 30-12-2007, 18:38

Quote:

Originally Posted by corradoboy

I've always found small petrol engined cars to be uneconomical. Had a 1.2 Corsa for seven months whilst I was training as a driving instructor and that never managed better than mid 20's. My old Impreza could average 33 if you drove like the pope's chauffeur. The problem is, for me anyway, that as there is virtually no power whatsoever you spend a lot of time with your foot flat to the floor, which forces a lot of fuel through an engine that can't do much with it. I also think small engines are unsafe, as often in dangerous situations the best course of action might be to boot it and get clear, and if your car can't do that then you're gonna get it. That's why I now teach in a vRS. I recently had it in for some repairs and had a Corsa diesel for a couple of days and all the learners commented on how pathetic it was to drive, having got used to the oomph

Small engines = false economy based on another eco-mentalist green lie.

Agree 100%

Also, I'd say lambda sensor. Unless completely knackered (or disconnected) then the ECU may not see it as faulty and so not light up the check lamp. It's readings may have just drifted with age and telling the ECU to overfuel to a fair degree.

How does it start and run when hot and cold? Lambda sensors only kick in when the exhaust temps have reached about 80 degrees and so are ignored when cold (open loop mode).

EDIT: Just read your mileage - O2 sensors normally get to about 60k before their readings start to drift in my experience. Personally, I'd change it, the air filter and plugs and then take it for a proper Italian tune up (aka warm it up and thrash the living **** out of it down an open road).

JohnAA · 30-12-2007, 18:39

Quote:

Originally Posted by kwacka

checked for binding brakes??

Not yet - need to have the wheels raised for this. It did cross my mind though.

Chrispy · 30-12-2007, 18:42

Quote:

Originally Posted by JohnAA

Not yet - need to have the wheels raised for this. It did cross my mind though.

Not really, they usually smell and also the wheels get hot after a run. Hot enough to feel through the wheel trim.

JohnAA · 30-12-2007, 18:45

Quote:

Originally Posted by Chrispy

...How does it start and run when hot and cold? ...

Starts and runs fine.
I wouldn't expect a sensor with 85K miles on it to be running 100%, usually they start drifting after 60K showing leaner than they should (causing the ECU to overfuel a bit)
But here it is way off, it would have to be knackered for mpg to be so lamentable. Surely the ECU warning light would have kicked in by then.
It's got to pass MOT on February, I guess emissions will reflect then any signs of sensor age.

JohnAA · 30-12-2007, 18:49

Quote:

Originally Posted by Chrispy

Not really, they usually smell and also the wheels get hot after a run. Hot enough to feel through the wheel trim.

Crickey, it would risk boiling the brake fluid then.
I've got a non-contact thermometer, worth checking the wheel temps after a drive next time, you never know eh.

Chrispy · 30-12-2007, 19:07

Quote:

Originally Posted by JohnAA

Crickey, it would risk boiling the brake fluid then.
I've got a non-contact thermometer, worth checking the wheel temps after a drive next time, you never know eh.

Worst case scenario, yes.

Missus car did it on the O/S rear caliper. Ended up getting it replaced as the piston had corroded and wouldn't retract smoothly. N/S then decided to do it too but that seems to have been ok since a good workout with a retraction tool and a drowning in copper slip.

Chrispy · 30-12-2007, 19:11

Quote:

Originally Posted by JohnAA

Starts and runs fine.
I wouldn't expect a sensor with 85K miles on it to be running 100%, usually they start drifting after 60K showing leaner than they should (causing the ECU to overfuel a bit)
But here it is way off, it would have to be knackered for mpg to be so lamentable. Surely the ECU warning light would have kicked in by then.
It's got to pass MOT on February, I guess emissions will reflect then any signs of sensor age.

Well, yes and no. In my E36 days, people were often complaining of crappy mpg but with no warning light (on post 1995 cars with OBDII also). Change of lambda sensor and all was well, and this was on cars that didn't have starship mileage. Circa 80k on some.

Not sure how far the readings have to drift for the ECU to complain to be honest but under normal circumstances the lambda sensor produces a voltage that fluctuates between 0.8 and 1.1v up and down.

30-12-2007, 10:34	#1
JohnAA Briskodian Join Date: Dec 2007 Posts: 34 Members Car: Thanks: 5 Thanked 0 Times in 0 Posts	1.4 MPi: 24.5mpg, WTF Just refilled it brim to brim after 235 miles. £45 At these prices, it can't even return 25mpg, that is what I get from the Supra during 'mild' motorway driving. Not The tyre pressures are OK (were 5-10psi down when I bought the car) What else should I check in order of importance now? My guess is to change the spark plugs. Air filter appears to have been recently changed in the service history. Is the fuel filter an issue with these cars? Anything else I may have missed? Fluid levels are all fine. It's got to be something obviously wrong here... Edit: just checked the service history printouts and it had new plugs (BKUR5ET) 3K miles ago. So what on earth could force mpg to be so low!? Last edited by JohnAA; 30-12-2007 at 10:52.

30-12-2007, 11:05	#2
djswivel Briskodian Join Date: Dec 2007 Location: Redruth, Cornwall Posts: 1,015 Members Car: Fabia vrs Images: 4 Thanks: 98 Thanked 51 Times in 48 Posts	Re: 1.4 MPi: 24.5mpg, WTF If you've done a lot of milage, the cat may have gone. Or it could be the lambda sensor - this really buggers up emissions. __________________ http://www.myspace.com/lackofpower

30-12-2007, 11:08	#3
corradoboy Briskodian Join Date: Jan 2007 Location: West Yorkshire Posts: 689 Members Car: 05 Fabia vRS Thanks: 4 Thanked 50 Times in 35 Posts	Re: 1.4 MPi: 24.5mpg, WTF I've always found small petrol engined cars to be uneconomical. Had a 1.2 Corsa for seven months whilst I was training as a driving instructor and that never managed better than mid 20's. My old Impreza could average 33 if you drove like the pope's chauffeur. The problem is, for me anyway, that as there is virtually no power whatsoever you spend a lot of time with your foot flat to the floor, which forces a lot of fuel through an engine that can't do much with it. I also think small engines are unsafe, as often in dangerous situations the best course of action might be to boot it and get clear, and if your car can't do that then you're gonna get it. That's why I now teach in a vRS. I recently had it in for some repairs and had a Corsa diesel for a couple of days and all the learners commented on how pathetic it was to drive, having got used to the oomph Small engines = false economy based on another eco-mentalist green lie. __________________ Diesel - Goes like stink

30-12-2007, 11:12	#4
JohnAA Briskodian Join Date: Dec 2007 Posts: 34 Members Car: Thanks: 5 Thanked 0 Times in 0 Posts	Re: 1.4 MPi: 24.5mpg, WTF Lambda sensor, good point. Why didn't I think of it, what's wrong with me? Is it accessible guys, is it a fairly universal type (i.e. cheap?) Cheers

30-12-2007, 12:13	#7
redbaron Briskodian Join Date: Jun 2003 Posts: 9,584 Members Car: Thanks: 18 Thanked 73 Times in 63 Posts	Re: 1.4 MPi: 24.5mpg, WTF you should easily be getting 35+ and into the 40's on a longer run... lambda sensor is worth a check.. reset the ecu (batt off for 10 mins should do it...) would also try some injector cleaner in case one is sticking? have you tried giving it a damn good thrashing ? one odd thought some hero hasnt tried uprating the fuel pressure regulator have they? this would explain the economy as it will be running richer than dodgy labour party donator......

30-12-2007, 12:58	#10
ric04vrs I parked up 1st Join Date: Jan 2006 Location: not near enough to the Ring Posts: 6,265 Members Car: silver Fabia VRS Thanks: 31 Thanked 193 Times in 187 Posts	Re: 1.4 MPi: 24.5mpg, WTF i'm sure a faulty Lambda sensor would throw the engine warning lamp on __________________ very bored and liable to do something stupid

30-12-2007, 15:00	#12
Duggie Briskodian Join Date: Mar 2007 Location: Oxfordshire Posts: 421 Members Car: Skoda Fabia 1.4 MPI Thanks: 11 Thanked 17 Times in 15 Posts	Re: 1.4 MPi: 24.5mpg, WTF My 1.4 MPi Returns around 25mpg... my mate has a M3 and it does better than that!! However, when I do drive economically i can get the actual MPG rating on the dispaly to hit 50-55 ish, the combined rating never gets that high though! Please let me know what happens with yours!! __________________ Dream as if you'll live forever, live as if you'll die today. Jabbasport rear ARB... (HELL YEAH) Weitec V1 coilovers. Vrs 16' Alloy Wheels. Forge Front Strut Brace. Sidestrips off. Colour coded front grille. Alpine IVA-D105R headunit twinned with a Novex bandpass sub enclosure 2X12 inch subs and a Fusion 1000W amp. Hornet Maxx1 auto alarm.

30-12-2007, 15:09	#13
smstext 2.0 FSI Sport. Join Date: May 2007 Location: oxon Posts: 10,491 Members Car: Octavia Mk2 FSI Sport Thanks: 13 Thanked 338 Times in 304 Posts	Re: 1.4 MPi: 24.5mpg, WTF have you had it checked with a vag com? might point at sometihng thats wrong. other than that has the car done alot of small 5 mins start/stop runs? I personally would but redex injector cleaner in and go for a very good boot in it and flush the system through and see how it goes after that. __________________ Oxon Meet 24 Jan 09 click here for more info Briskoda Summer Camp Trip June 2009 click here!!

30-12-2007, 15:52	#15
JohnAA Briskodian Join Date: Dec 2007 Posts: 34 Members Car: Thanks: 5 Thanked 0 Times in 0 Posts	Re: 1.4 MPi: 24.5mpg, WTF What's the italian tune-up guys?

30-12-2007, 17:30	#16
Tom_vRS Briskodaholic Join Date: Dec 2004 Location: Fenland, Cambridgeshire Posts: 11,793 Members Car: '97R BMW 328i Saloon Thanks: 728 Thanked 451 Times in 328 Posts	Re: 1.4 MPi: 24.5mpg, WTF Thrash it!!! Get the engine nice and hot, a good 10 miles in 3rd gear at 60mph would do it. __________________ 97/R BMW 328i in Boston Green.

30-12-2007, 18:34	#18
kwacka Briskodian Join Date: Dec 2006 Posts: 285 Members Car: Thanks: 14 Thanked 35 Times in 35 Posts	Re: 1.4 MPi: 24.5mpg, WTF checked for binding brakes??

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