General Forum Guru's

[phonesurgeon]

I need your help regarding my Mk1 Punto 55

The problem: smelling as if it is running rich, thus fuel consumptions high (15-20 mpg) before i drove to Italy (4k return trip) the car consumption was in the region of 45mpg.

what are my best options?

 

[Ffoxy]

Well as you dont mention already doing this, try the air filter.
Check tyre pressures are correct & that no brakes are binding.
Next see if the coolant temperature sensor is working.
Maybe clean out the throttle body.

See what all those do before planning other work.

 

[phonesurgeon]

Ffoxy thanks for the tips... i usually clean the air filter with compressed air at least once a month, the brakes aren't binding(just changed discs and pads), the tyres are ok.

Coolant temp sensor next on the list... clean throttle bodies? do i use any chemical? as it looks pretty clean(from the outside... maybe take em off and give a thorough clean?)

Any other suggestions?

P.S. forgot to add, the car start easily but on idle/tickover it sounds rough, like a tractor and this is when you can smell it runs richer...

 

[Ffoxy]

Then the last point, sounds like possible coolant temperature issue. Check the coolant is actually in contact at all times with the sensor initially, if not it fools the ECU into thinking the actual coolant is still warming up so keeps the mixture rich. Or the sensor may be faulty. So first off purge any air from the cooling stystem. If thats all ok then probably the best way of making sure the sensor is OK is fit a new one...

Then maybe on to the injectors... these can be ultrasonically cleaned... but not yet huh!

Use ordinary Carb cleaner or the suchlike on the TB...

 

[blu73]

I'm not far from harrogate and have a ultrasonic bath big enough for some injectors (read small), if it comes to that..

 

[phonesurgeon]

Ffoxy thanks again...
i will get multimeter out and check the coolant temp sensor...

I have an ultrasonic cleaner(i use it with pcb's) and i'll give it a go... tomorrow tinkering time, methinks.

Edit: just so i am clear the coolant temp sensor is the one on the radiator?
Apology if this sound strange but english is not my first language.

 

[dumbledore]

coolant sensor is not on radiator. It will be on the engine somewere.
Also high fuel consuption could be caused by faulty oxigen sensor(lamda sensor). Either way coolant or lamda sensor if they broken your engine should still have good power at full throtthle. If the car does not have the power then there could be other problems.

 

[blu73]

no that one is the cooling fan switch.. its on the inlet manifold and its blue

 

[fingers99]

The trick with the injectors (you're lucky having only one) is said to be one wash to get the general muck off, then another but pulse the injector with 12v across the terminals while it's in the bath.

 

[phonesurgeon]

dumbledore yes car has power at full throttle... just consumptions are horrendous. So coolant temp sensor or lambda sensor... something to go on.
blue73 thanks for the explanation.
fingers99 will do that...

 

[phonesurgeon]

Mini Update:

I ve ordered both the coolant temp sensor and the lambda sensor awaiting delivery tomorrow (or thereabout).
Over the weekend i have given the jet a thorough clean in ultrasonic cleaner and carb cleaner.

Will post results after fitting new parts.

 

[phonesurgeon]

UPDATE:

Fitted new lambda sensor and new coolant temp sensor... aaaaaaannnnnnddddd
it didn't solve my problem.Car is still smelling rich, and still return 20mpg.

What do you guys think? I am baffled...

 

[Ffoxy]

Are you sure there is no air lock around the coolant temp sensor? If there is the sensor will instruct the ECU to run rich. I'm assuming there are no codes embedded in the ECU at all?

 

[phonesurgeon]

Ffoxy thought about that aswell... but no.

I ve read on google that a faulty air temp sensor could cause same symptoms...(running rich) could it be?
The car is a Mk 1 punto 55S and i don't have any code reader for it...

 

[fingers99]

Pinched earth to the injector, air temperature sensor...............

 

[dumbledore]

Could be the actual CAT damaged. blocked?. If you can test it. I vacuum meter may work, not sure if will though on a MK1, as there are no obvious vacuum pipes you can remove. Also it may be possible the air flow meter if it has one to be faulty. A genuinely faulty ECU may do that. So if the problem is not obvious you need to experiment before you replacing the item as it will get expensive.

 

[fingers99]

If the cat was blocked you'd expect a very dramatic drop in performance.

Lambda is worthy of a peek/test.

 

[phonesurgeon]

Fingers the lambda sensor is brand new asnd the car pulls in all gears and i was close to triple figures. So cat excluded. next job will be the air temp sensor... failing that i will sell the car for another 1

 

[GeorgeDamper]

Take the air filter box off and start the car. Have a close look at the injector - they can leak and dribble excess fuel into the SPi unit. This is normally associated with difficult hot starting but it only takes 5 minutes to look anyway.

 

[dumbledore]

Also could be the obvious, ignition problem causing a misfire hence the petrol smell. So check ignition leads (they can be a bustard to attach to the plugs so they may have come loose) and coils. Also take out the spark plugs to assess the severity of the overfuel. Also misfire could be caused by mechanical problem, so while you have the spark plugs out do a compression test. You never know you may have a head gasket starting to go, a burned valve, etc. If you don't have a smooth idle misfire is a strong contender for the problem.