O2 sensor live data.

[norfolkmatt]

Car started to be a bit hesitant and a slight misfire so had a quick look on my rstuner.

Had a current fault Rear o2 heater sensor, checked plug was corroded so wired in bypassing the plug hoping if would just be that.
Still got the fault so had a quick look on the live data and it was showing this. Looks like the rears fine but the front is goosed and should be fluctuating a hell of a lot more than that suspect Causing my misfire?
I've got a spare rear lambda read they're universal?

 

[Joe'172]

Both look smoked. Doesn't the graph have a time vs voltage plot?

 

[Chris.C]

The rear one is meant to flat line as that's only a diagnostic probe, so doesn't actually influence anything.
The front one should be anywhere I between 100mv and 700mv, and fluctuating a lot more than that like you say.

That graph looks a lot like my gf's graph on her fiesta st, I know it's a different car but she had a slight misfire, changed the lambda and it cured the problem and the graph looked normal again.

Id say give that spare one a try that you've got as the front n rear lambdas are the same iirc

 

[norfolkmatt]

Yeah I was pretty sure the front should be 700 something mv max?
The cable long enough to use a rear on the front?

 

[Joe'172]

I though they were both 12v sensors and the front is also heated so it brings temps up quicker on cold start.

Front should fluctuate between 4-800mv and the rear downstream used to measure gases after Cat. Hence why after de cat most people encounter EML lights.

I may be wrong.

 

[norfolkmatt]

Nah I think your right, the front definitely isn't right.

 

[Sean6545]

Front isn't working as it should. As above it should fluctuate between 100 - 800 mv aprox.

Is the engine up to temp?

 

[norfolkmatt]

Yeah engine is up to temp, just jacked the car up at home and I've got a horrible feeling my cat has gone, blowing and rattling quite bad...sensor was too tight so will get u.it up on the ramp at work and have a look.

 

[Dan519]

pre cat sensor signal is a 1000mV (1V) range. It's a switching signal, between roughly 40mV and 950mV