18L per 100km ?!?

I almost froze myself when I spotted this! Any ideas?
Authorized Fiat service center suggested that they should rinse injectors ?!?
Maybe I haven't translated this properly (but they sure suggested some washing!). Anyway, they also said that everything appears to be normal (so the board computer says)...The point is that they are not sure if this washing will help. All filters are brand new and there is no issue about them. I have also searched and discovered that some sensors can take the guilt for this (as I recall, it was oxygen or lambda sensor...something like that). I hope that someone here recognizes what I'm trying to explain (and it is obvious that I am not an expert on this issue :bang: ). Does anyone knows where those sensors are located, can they take the guilt for this problem...any suggestion will be appreciated.

Thanks.

leave the injectors, it would be a waste of time and money. if the car performs fine the injectors arent the issue.

it would help if you stated the model you have, and age and milage.

the lambda sensor is always a possible cause of poor fuel economy, and can show no other symptoms. you can test it easily, but i need to know which model you have before i can help you test it. dont go buying a new one unless you test yours first.

18L per 100km:

18/4.54= 3.96 UK gallons

100km =62.14miles

62.14/3.96= 15.69mpg.

Lambda sensor is usually at fault for other things aswell, like juddering on part throttle and uneven idle etc etc.

Could be thermostat or the like?

Does your thermostat get above 60 at any point?

Ross

by thermostat do you mean overcooling (thermostat stuck open) causing overfueling (cold fueling strategy in use for too long)?

if that was the case you would notice the temp gauge was sticking right at the bottom for a long time after the car is started.

that would cause a loss of fuel economy.

jug said:

by thermostat do you mean overcooling (thermostat stuck open) causing overfueling (cold fueling strategy in use for too long)?

if that was the case you would notice the temp gauge was sticking right at the bottom for a long time after the car is started.

that would cause a loss of fuel economy.

Click to expand...

Yeah thats why i asked about the temp. Some people are unsure of what is normal and whats running cold. If it doesnt get above 60c then the thermostat is running cold all the time causing extra fuelling to be pushed in.

Ross

Many thanks for the fast answers, guys.

The car is Fiat Brava SX, 1.6-16V, year 2000. Eveything else works perfectly, this fuel consumption is the only thing that's killing me. How can that lambda sensor be tested? Also, I will try later on to check the temperature scale (and to see is it stucked as you mentioned)...

the consumption is too much... This once happened to me and turned out to be the lambda. Usually the starting when hot problem goes with it.

Also are you sure there are no leaks? do you smell a smell of petrol?

A1ex said:

How can that lambda sensor be tested?

Click to expand...

you need to disconnect its connector, and then use a multimeter to measure resistance of the heater and the probe as described in the following pic.




to access the connector you need to remove the black plastic cover at the back of the engine bay, slightly to the left of centre when looking into the engine bay. there are 2 knobs you loosen off and then you can pull the cover away. behind there are a few connectors, the one that has 4 wires, and a white sheath over the wires on the right hand side of the connector, is the lambda connector. you can tell if you've got the correct connector using the above pic.

Hey, thanks for the tip...
I will do that right away and I keep you posted.
Once again, many thanks for precious advices.

Hey JUG, thanks for the instructions. I did it exactly as you told me to do.
I tested it few minutes ago and here are the results:

Probe resistance (B): cannot be measured (always goes beyond the scale)
Heather resistance (A): from 5.3-5.8 Ohm.

I have attached an image (just to make sure I did it right)


Also, I'd like to mention that I was looking into the temperature gauge also (based on h2ypr idea), and after 10 minutes of driving, the scale barely moved from it's initial position.

Sorry just to but in on this topic but my car has always not liked starting from hot a idles irratically sometimes. Also sometimes stalls when i put the clutch down into corners and i loose power steering. Also juddering acceleration sometimes. S i tryed unplugging my lambda sensor and it made no difference to the car atall. Do i need a new one as i dont have a multimeter.

Also is there anyway i can take it out and clean it or does it work in a different way?

Found a meter tested the pins in the plug and they read no current atall for all 4. Either the meter is crap or the lambda is dead. The meter reads 12v for the battery so it is working :S

A1ex said:

I did it exactly as you told me to do.
I tested it few minutes ago and here are the results:
Probe resistance (B): cannot be measured (always goes beyond the scale)
Heather resistance (A): from 5.3-5.8 Ohm.

Click to expand...

I would definately change the lambda based on that info. it failed both tests.

A1ex said:

Also, I'd like to mention that I was looking into the temperature gauge also (based on h2ypr idea), and after 10 minutes of driving, the scale barely moved from it's initial position.

Click to expand...

that does sound like the thermostat is stuck open. its not very difficult to remove, and then test using some water in a cup. in cold water it should close completely, in very hot water it should open completely. check a haynes manual for further details. try cold starting the car and leaving it to idle, to see how long it takes to warm up (idle drops to 850rpm). it should only take 5 mins for then idle to settle.

reaper1988 said:

Do i need a new one as i dont have a multimeter.

Also is there anyway i can take it out and clean it or does it work in a different way?

Click to expand...

you dont test the lambda by checking for current on the pins. you need to measure the resistance across 2 pins, as shown in the pic. resistance and current are different things, read the multimeter manual

you can't clean a lambda, well you can try but i've never heard of it making any difference.

Ahhh ok well i dont think the multimeter works properly anyway (some cheap one from a discount store) Do you think my sensor is dead from the info i gave or cant you tell unless i get a multi meter test?

reaper1988 said:

cant you tell unless i get a multi meter test?

Click to expand...

yep its hard to say

Cheap enough to replace anyway to be honest, been as you already have access to it

Mine was cleaned as opposed to replaced once but then I had ongoing exhaust problems with other symptoms that was causing a build-up of crap I just keep a spare one now just in case.

I did try removing it but it was stuck tight. I didnt want to shake the car to much with me under it on jacks so will get me mechanic to do it when i get a new one. Any cheap places you can advise me on getting one?

Brava ELX 1.6 96

motorfactors

Hey Jug, many thanks for your answeres and advices...
I will replace the lambda within the 48hrs (as soon as the shops starts workin' again....easter holidays and all that), and I will get back here as soon as it is done..

Stay sharp and happy easter to everyone!!

If the temp aint moving much from the bottom of the temp gauge, then replace the thermostat. No point testing it in my opinion as while its out might aswell replace, because it will need done at some point. They always do.

As for the lambda, reapers problems sound EXACTLY like a lambda problem. Replace and as jug said it should clear that up.

Helz - cleaning the lambda sensor is a good temporary measure usually (temporary being the operative word. Could be 2 months could be 2 years till it needs replaced)

The carbon builds up on the lambda blocking its ability to properlly gauge fuelling, hence it believing that its getting either less or more fuel than required.

Ross

Well once i get a new one fitted which prob wont be for a while as i have to fix my silly suspension problems and get more £££ i will dig up the thread and tell you if it fixed anything :slayer: