Ahhh! my 1997 1.1L punto 55s has been gradully drinking more and more even more quickly.

Before MOT it was doing 36ish mpg, a little low compared to others but its 4,800 miles overdue a timing belt renewal.

Took the car to Kwick fit for the MOT, never used them before (1st car - 1st MOT), my dad paid for all of the work to be done. It failed the MOT for exessivly corroded rear suspension and brake lines, advisary item was the Cat - corroded

Its now passed MOT but has a rattling exhaust, (They used metal things instead of rubber things to surport it / hold it to the car) Fair enough, no big problem, exhaust only rattles when cars doing half its idle speed.

Clutch feels like it need bleeding and the car no longer has much mid range power, - all low and very high. (shame really coz i only ever used low / mid range revs)


i dont what to take it back to them coz of the crap job they did to start with, i have been used to working on the car, fixing in to get on the road to start with, MOT just wasnt somthing i could do. suspension wasnt bad but an MOT's an MOT.

more recently the mpg has continusly fallen since the MOT from 36ish to 18Mpg, Before the MOT i had changed:

Engine Oil (And Filter)
Clutch / Brake Oil
Clutch Slave clyinder
Wiper Motor (Front)
Brakes
Spark plugs
Tyres
Air Filter


If anyone can see that i've done something wrong, or missed something please tell me.
Any suggestions to get the MPG back upto 45 please say.

Easy stuff first.

Check for fuel leaks along the supply line and at the fuel tank for starters.

Then check the brakes are not binding.

Next make sure all tyre pressures are correct.

Then let us know...

Tyre pressures:
Front
26psi 26psi


27psi 17psi - missing cap for valve
Back
^ Tyre Pressures are the same as when the car was doing 36 mpg ^

Fuel might be leaking from the carb part above the inlet - not alot just looks damp. (Again bought the car like this when doing 36 mpg)

No leaks anywhere else, no brakes binding.
Nothing looks wrong with the car, car drives well..

It could be the lambda sensors

They might have damaged them when they replaced the cat

will4318 said:

It could be the lambda sensors

They might have damaged them when they replaced the cat

Click to expand...

Causing over-fuelling... like driving with the choke out in an older car...

TBH I'd still sort out the tyre pressures.

sniff the wet patch (no smutty remarks please) if it smells like fuel, treat as if fuel and check hoses/clamps. If left it could end up a fire and no as in fully integrated robotised engine but the hot stuff.

it smells a mix of both fuel and oil so it might be from the breather tube - no clamps on the tube in my car but on my bros '91 Panda there are clips?

Ffoxy said:

Causing over-fuelling... like driving with the choke out in an older car....

Click to expand...

:yeahthat:
It happened to my mk2 brought the mpg down to 20ish

They can be damaged easily and as the exhaust has had work done it seems likely to me

A fuel leak causing that much loss would leave a puddle under the car wouldn't it?

Would tyre pressures make that much of a difference?

Not usually as petrol evapourates rather fast so no trace is left, it usually evapourates before it drips.

Tyre pressures can make quite a difference but not that much

A fuel leak big enough to quadruple the fuel consumption would stink of petrol. Its got to be going though the engine. The Lambda sensor is the place to start but don't neglect the throttle body, inlet manifold breather system and of course it is firing on all 4 pots?

Slightly off the topic but did you change the fuel filter? It might be choked with debris and dirt and it may putting pressure on the lines before it. This may even have caused a leak and it may be leaking as you drive...

Did you say you got a new cat? We got an aftermarket cat for our Tempra years ago. It was immediately noticable how crap it was compared to the original, despite being significantly smaller. It never reached 41mpgs ever again after that, the very best it could do was 38 with a struggle....

Use a multimeter to test the oxygen sensor, the old analouge one we have here has a designated setting for reading the normal operating resistance for oxygen sensors and such other parts with similar electronic properties

The fuel filter has not been changed by me. its been changed twice during the cars life time and it has done 48,000 miles. last change at only 43,000 (3 years ago).

There used to be a burning smell but not of petrol, this smell has since gone with a new radio.

The sensors, i dont know how to check these and with a lowest price tag of £60 im not looking to replace them. does anyone know where i can find these any cheeper or have any other suggestions to this low Mpg.

Lastly, i've been getting a static shock off the car for the past 3 months or so, about a month before the Mpg fell, would this be related?

If you have a digital multimeter then you can test the Lambda sensors

It says how to do it here http://www.lambdapower.co.uk/Diagnosis/Diagnostic_index.asp#q11

If it is them you will soon make up for the cost in your petrol saving

just an update, the car is now running 36 mpg again, i havent done anything to it though...

at a guess its an eletrical problem - mainly becuase i havent done anything to it and it appears to have fixed itself!

Thanks for all your help, if anyone has a similar problem and finds out what it is please tell me!

MadMan0 said:

just an update, the car is now running 36 mpg again, i havent done anything to it though...

at a guess its an eletrical problem - mainly becuase i havent done anything to it and it appears to have fixed itself!

Thanks for all your help, if anyone has a similar problem and finds out what it is please tell me!

Click to expand...

strange! good news though. but keep an eye on that fuel at the throttle body, personaly i'd put a jubilee clip on it to be on the safe side.

AHHHHH!Ahhhh

This issue has come back?! gone from over 75mpg on the last tank down to 18mpg?!

Known issues with the car at the moment:
Hole in exhaust back box
Gearbox transmission minor leak
Odd sounding engine - NEW ISSUE - started when fuel went below 3/4 tank

engine eletrics are all new
Fuel system renewed also
New HG fitted a while back
Full Service at the same time as the HG

NO signs of the HG being faulty since it was done
It was redex in the tank again - might be the cause as a strange noise developed last time i used it

Tyre pressures all Good.
Tyre profiles all Good

Top speed is above 90mph so performance is no worse...
No smoke from exhaust
Exhaust sound go's every now and again - i.e no sound! (still not worked this one out happens when you go over 80)

Went to race track not to long ago - hence the over 80mph, the car ran perfectly before, during and after the track (a few months ago)

The car is dirty black stuff in the rain here (UK-London)


Over than the strange noise at start up - "KA-Boom" and car jolts when you first start it from cold - and the lower mpg than normal it go's well

Any Ideas?

My bad...

Fuel gauge fault - showed empty with warning light with more than 10L still in the tank

Mpg worked out at 45mpg - still lower than average but a recent clutch fault which i forgot to mention may have played a role in that

Fuel consumption is only remotely accurate when you record miles between brimmed tankfuls. All the fuel gauge does id help you avoid running out of fuel.