Very low MPG.

[Westbeef]

Hi All,

My MPG is very low, I'm talking 19MPG calculated, 22MPG on the screen.

I'm not driving like an idiot - i'm driving quite sensibly.

Where can I look to the problem for this?

I'm currently having an issue with ABS/wheel bearings which I'm in the process of sorting, can this cause the low MPG?

Thank you.

1.4 Sporting Mk2B

 

[homeward]

That's less than half what I'm currently getting on my 1.2 16v....

Unless the brakes are permanently dragging (which would probably end up with very hot wheels -- which you'd be able to feel, at the end of any trip; and would probably make some sort of indicative noise (which, I suppose, you could mistake for wheel bearings going...)), I'd suspect something else. What exactly is wrong with the ABS; and how do you know the wheel bearings are going?

Have you done a code read? Is the engine light on...? Is there any leak on the air intake side, or the breather hose...? The only reason I'm asking is that the engine could be over-fuelling, to compensate.... :chin:

Otherwise, before I have my first espresso of the day, I'm out of ideas. Sorry.

 

[Westbeef]

That's less than half what I'm currently getting on my 1.2 16v....

Unless the brakes are permanently dragging (which would probably end up with very hot wheels -- which you'd be able to feel, at the end of any trip; and would probably make some sort of indicative noise (which, I suppose, you could mistake for wheel bearings going...)), I'd suspect something else. What exactly is wrong with the ABS; and how do you know the wheel bearings are going?

Have you done a code read? Is the engine light on...? Is there any leak on the air intake side, or the breather hose...? The only reason I'm asking is that the engine could be over-fuelling, to compensate.... :chin:

Otherwise, before I have my first espresso of the day, I'm out of ideas. Sorry.

I know the rear breaks are hot when I pull up but it's always after a 30 min journey so I presume that is normal? I've got the ABS light on - changed the sensor which hasn't sorted it so it's pointing towards wheel bearing. (The reading for ABS light said Speed sensor issue) I haven't checked for air leaks on the intake side of things but I do have a blowing exhaust - how badly can this affect MPG?

I've also got a new Thermostat to put in, but I can't see a thermo reducing my MPG by 15 (I was a steady 35 MPG a week ago).

 

[homeward]

I know the rear breaks are hot when I pull up but it's always after a 30 min journey so I presume that is normal? I've got the ABS light on - changed the sensor which hasn't sorted it so it's pointing towards wheel bearing. (The reading for ABS light said Speed sensor issue) I haven't checked for air leaks on the intake side of things but I do have a blowing exhaust - how badly can this affect MPG?

I've also got a new Thermostat to put in, but I can't see a thermo reducing my MPG by 15 (I was a steady 35 MPG a week ago).

I think you may have just answered your own question...!

Firstly, why the new stat...? If the engine isn't getting up to temperature, then you will be overfuelling, I'm afraid. A blowing exhaust -- depending on how badly it's leaking -- won't be helping....

Secondly, brakes/wheels shouldn't get hot, during normal usage, unless you're doing lots of high-speed-curvy-bends-type driving.... (Mind you, I haven't driven like that for a while...!) Can't remember if -- but am guessing the answer is yes -- the 1.4 has disks all-round.... :chin:

More questions.... Have you managed to clear the ABS warning light? Do you get the usual wheel-bearing 'graunching' sound? Does it change when you turn rapidly one way or the other? Which wheels are affected....

My suspicion is, that, once you've sorted out what's wrong with the wheels/brakes; and replaced the exhaust and 'stat; that your consumption will improve markedly. Personally, I'd start with the wheels.... :idea:

 

[Westbeef]

I think you may have just answered your own question...!

Firstly, why the new stat...? If the engine isn't getting up to temperature, then you will be overfuelling, I'm afraid. A blowing exhaust -- depending on how badly it's leaking -- won't be helping....

Secondly, brakes/wheels shouldn't get hot, during normal usage, unless you're doing lots of high-speed-curvy-bends-type driving.... (Mind you, I haven't driven like that for a while...!) Can't remember if -- but am guessing the answer is yes -- the 1.4 has disks all-round.... :chin:

More questions.... Have you managed to clear the ABS warning light? Do you get the usual wheel-bearing 'graunching' sound? Does it change when you turn rapidly one way or the other? Which wheels are affected....

My suspicion is, that, once you've sorted out what's wrong with the wheels/brakes; and replaced the exhaust and 'stat; that your consumption will improve markedly. Personally, I'd start with the wheels.... :idea:

The temp is about 3C short of 90, it's hard to tell on these they aren't numbered .

The ABS issue is an odd one - the lights don't come on for the first 2 mins of driving and during the period pushing the break pedal causes a grinding feeling like ABS is permanently ON when breaking. Soon as the error light comes on the pedal slackens a bit and breaks work as expected. Can't clear the light trying a few things, the next being this wheel bearing.

I'm hoping I can plug my exhuast with some putty for the time being - I can't afford a new one or even a section to be fitted .

Edit: Also I think it's drums on the rear .

 

[Speedwell]

Many years ago, I had grinding when pressing the brake pedal. It was caused by one brake pad being worn down to the metal due to a partially stuck piston, which would push forward under the high pressure in the hydraulic line but not retract. Have you checked your pad thickness ?

 

[Westbeef]

Many years ago, I had grinding when pressing the brake pedal. It was caused by one brake pad being worn down to the metal due to a partially stuck piston, which would push forward under the high pressure in the hydraulic line but not retract. Have you checked your pad thickness ?

I haven't I've meant to change them but with so much going on with everything else I've neglected this. I'll get it done ASAP then, even if I stick cheap pads on it's better than nothing. It doesn't grind when the ABS fault light is on though? Maybe it's just not breaking on that wheel at all at that time then?

Also any tips on changing thermostat without requiring a bleed afterwards? I've seen how painful that can be .

 

[Speedwell]

I haven't I've meant to change them but with so much going on with everything else I've neglected this. I'll get it done ASAP then, even if I stick cheap pads on it's better than nothing. It doesn't grind when the ABS fault light is on though? Maybe it's just not breaking on that wheel at all at that time then?

Also any tips on changing thermostat without requiring a bleed afterwards? I've seen how painful that can be .

I'm not suggesting that must be the cause but worth a check. My experience was from before abs was in use - mk2 cortina IIRC.
Sorry, no experience of changing Fiat thermostats.

 

[varesecrazy]

Also any tips on changing thermostat without requiring a bleed afterwards? I've seen how painful that can be .

top up coolant to MAX level,
replace cap.

remove battery - for better access,

leave rad cap ON,

undo the 2 x 10mm bolt heads wiggle thermostat off,
undo hose,

replace hose clip, if required

clean off mating faces, install new gasket, a little goo on gasket faces,
install 2 x bolts,
tighten hose clip,
tighten 2 x bolts,

check coolant level, should have dropped by @ 0.5 litre, TOP UP to MAX.

leave rad cap off and run up engine for 2 x mins,
then leave to cool,
top-up level again and replace cap,

check for leaks after a short drive,

check level for a few days..,

Charlie

 

[Westbeef]

I've purchased, Pagid Front disc pair, set of pads for the front pair too. Also got a new handbreak cable as I need a new one of them. All for a tidy sum of £78 .

Will update after weekend when I've put the new breaks on .

 

[varesecrazy]

I've purchased, Pagid Front disc pair, set of pads for the front pair too. Also got a new handbreak cable as I need a new one of them. All for a tidy sum of £78 .

Will update after weekend when I've put the new breaks on .

take your time with the brakes,
do 1 side at a time and make sure EVERYTHING is CLEAN

have fun with the handbrake cable.. often an awkward / time consuming job.. but as always.. well worth doing,

Charlie

 

[fingers99]

Also, a holed exhaust can fool the lambda into thinking that the car is running lean. The ECU will add fuel to correct (but, in this case, in error).

 

[Westbeef]

The Thermostat on gave me about 2 more MPG and it's sat on the perfect temp now. Thanks to Big Mick for that , I will update on the brakes on Sunday and When I've got it on stands Sunday I'll find the source of my blowing exhaust and try patch it up until payday.

 

[varesecrazy]

back boxes are dirt cheap , and easily DIY -able,

should be less than £40 fitted,
sure my last one was £26 delivered and £3 for a tube of assembly paste.

 

[Westbeef]

back boxes are dirt cheap , and easily DIY -able,

should be less than £40 fitted,
sure my last one was £26 delivered and £3 for a tube of assembly paste.

It's blowing from near the manifold , I just haven't located as to where yet.

Brakes changed over weekend - found that the drivers side pad had binded to the disc. I thought this was the cause of all my problems but changing it hasn't really mad a difference yet. There's no scraping to be heard and it brakes fine now so I don't think it is still binding. Pads themselves had decent life in them but the discs were badly scored. See below

 

[varesecrazy]

It's blowing from near the manifold , I just haven't located as to where yet.

Brakes changed over weekend - found that the drivers side pad had binded to the disc. I thought this was the cause of all my problems but changing it hasn't really mad a difference yet. There's no scraping to be heard and it brakes fine now so I don't think it is still binding. Pads themselves had decent life in them but the discs were badly scored. See below

the exhaust leak will most likely just need a new gasket..,
pain to do as you'll have to soak all the nuts for days before stripping : - {


but will cost less than £5, and being pre-lambda..should make a BIG difference to running / MPG.


did you notice any differences in resistance winding the caliper pistons back in..??
of do you think it was the "sliding fame" doing the sticking.?,
charlie

 

[Westbeef]

the exhaust leak will most likely just need a new gasket..,
pain to do as you'll have to soak all the nuts for days before stripping : - {


but will cost less than £5, and being pre-lambda..should make a BIG difference to running / MPG.


did you notice any differences in resistance winding the caliper pistons back in..??
of do you think it was the "sliding fame" doing the sticking.?,
charlie

The pistons didn't slide back in easily - took a fair bit of force on a small G clamp but I'm not sure what's normal. First time doing it . But Drivers side was much more difficult to push back in then passenger side.

 

[varesecrazy]

sounds as if that the drivers side. may well be a bit sticky then..

just keep en eye on the temps,
after a 10 + minuute drive - trypulling up gently using the handbrake , then compare the temp of wheels / wheel nuts,
on front pass + drivers wheel areas.. if the drivers side is binding it will be HOT - rather than warm,

charlie

 

[Westbeef]

sounds as if that the drivers side. may well be a bit sticky then..

just keep en eye on the temps,
after a 10 + minuute drive - trypulling up gently using the handbrake , then compare the temp of wheels / wheel nuts,
on front pass + drivers wheel areas.. if the drivers side is binding it will be HOT - rather than warm,

charlie

They were both hot (couldn't touch the disc) after a 5-10 minute drive, I guess this means I'm looking at new calipers .

 

[fingers99]

Try pulling up without using the brakes.

Buying new is a possibility, but exchange is also possible -- try http://brakeparts.co.uk/ for example.

Important to get that sorted, but don't neglect other possible causes.