Technical Lambda sensor high voltage!

[anchorless]

Hi Guys. First post but long time lurker

Looking for some help with my 96 1.6 brava

Red Injector/Engine light on. Very lumpy, very juddery, when I put foot down power seems somehow restricted, even flat out, foot to floor I struggle to get over 40mph. Very high petrol consumption (20mpg at best!). Checked the spark plugs seems ok

Reading (many) threads on here I got the impression it could be the Lambda sensor. Pulled out the plug today and stuck a voltmeter on it.. At cool/idle get 0.2/0.3 volts which rises to 0.5/0.6 after a while.

However, when I put my foot on the pedal it shoots up, just took a reading of 2.8V?!??!

Am I doing something wrong or is the lamda definitely screwed??

please dont tell me to take it to a garage, I paid £200 for the car and I don't want to spend a penny more than i need to keep it going! A Lambda sensor (if necessary) is my last ditch attempt before the scrappers

THanks!

 

[Gregovic]

I have no experience with Lambda fault nor do I know the correct values, maybe someone else could jump in on that. HOWEVER, the only easy and surefire thing to do is the one thing you don't want to. The Engine management light means the ECU has logged a fault and knows whats wrong. If you take it to a garage they can tell you exactly whats wrong with it. (Or maybe someone in your area has a fault reader and can do it slightly cheaper.) For things like this over a forum it'll always be a bit of stab in the dark.

Just to be sure you might also want to check resistance of the injectors with a multimeter. They can get bad on a 1.6. For easy measuring, when standing in front of the car, on the right of the engine (Near side for you crazy brits) there is a 5 channel connector for the fuelinjectors on the fuel rail. One of those pins is the earth (the center one if I remember correctly) the others are then for each injector. Resistance should be above 13 Ohms. Anything between 11 and 13 Ohms means they are on the way out and might not be working correctly anymore. Below 11 ohms they are most often completely nackered. (new injectors are roughly 150 pounds at the dealers. They can also be found a bit cheaper. A full set of 4 used ones from a scrapper would be about 60 pounds I think.

 

[aurick86]

Hello,
-the correct lambda values are between 0 and 1 volt ( WITH THE ENGINE AT OPTIMUM TEMPRATURE).
--closer to 0= lean air-fule mixture
--closer to 1= rich air-fule mixture
-the value should go up and down very fast it should read 0.3v ..0.8v
-the lambda value for stoichiometric air-fule mixture is about 0.45v

the thing is there are 2 types of lambda sensors :
-narrow band
-wide band
I'm not sure about this but i think wide band sensors read more than 1 volt ( like 2-3v)

Fiat bravo take narrow band it should read maximum 1 volt how ever rich the mixture gets.

I have mounted a non original lambda sensor from a Renault Logan ( or Dacia Logan) as the parts for this car are very cheap ( it's built here in Romania ) about 10 ponds.
This O2 sensor has 4 wires and fits perfectly (except the connectors, wich i had to solder).

Buy an universal narrow band sensor and solder the connectors on it.

Please correct me if i made any mistakes.
Cheers!

 

[anchorless]

Strangely enough its fixed itself now!
No more engine light, running fine (or as fine as it ever did!) :bang:

I did test the injectors and the 2nd pin was only reading 5ohms (both before and after the problem fixed itself) - does this mean this one has had it? and if so, how come the car seems to be running ok now? Is it possible its intermittantly working?

 

[Gregovic]

It is possible its still working somewhat, and is capable of keeping the engine running. (I have one at 8 Ohms thats still working) Most likely however the spray pattern is no longer uniform and correct and it's not firing correctly at all times. This would mean higher fuel usage for sure and can cause engine wear aswell.