General Quick Lambda Sensor Reading Question

[Greggers]

I've just run a test on my car to check that the lambda sensors are working correctly and it looks like the pre cat one is fine, oscillating betwen 0.1v and 0.8v regularly at idle and then dropping to 0v when revved. The post cat one though I'm not sure about...

At idle, it was sitting at 0.8v which I believe is normal but when the engine was revved, it drops to 0v and then very slowly increases but not back to 0.8v. It sat at about 0.2v and stayed there

I've attached a couple of pics to show what was happening

 

[12[X]]

My post cat is quite similar.. am guessing the heater is gone as it comes back to life during a drive; unless the ECU stops heating the sensor at idle? If you’ve a 1.8 – that’s 2 with this behaviour now

 

[Deckchair5]

No, those are good looking traces Greggers
At steady tickover your pre cat O2 is oscillating nicely and your post cat is recording- note the ripples- and is showing steady state low reading at tickover. This shows good closed loop operation, no exhaust leaks and both O2 sensors working as they should


Here's a similar healthy trace of steady idle and a rev up at the end



Your trace above is quite different 12X in that yours show total flat line, no response, no ripple and even revving the engine produces no effect whatsoever on the post cat. The post cat O2 shows off temperature or dead. Classic O2 heater circuit problem

 

[Greggers]

Thanks Decks, always good to hear!

I'm sure I've asked you this before, but what software are you using? It looks really useable with clear accurate graphs... I like it! I've just got my ELM327 and am looking for the best software for it. What I'm really looking for is one that can read the injectors so I can work out the duty cycle of them

 

[Deckchair5]

That's a Gendan diagnostics readout there and that's with an ELM interface but that doesn't do coil duty cycle, for that then the FiatEcuScan download up above works well and does quite a bit of other stuff not normally available but for that you need a straight through VAG type interface

 

[Greggers]

That's a Gendan diagnostics readout there and that's with an ELM interface but that doesn't do coil duty cycle, for that then the FiatEcuScan download up above works well and does quite a bit of other stuff not normally available but for that you need a straight through VAG type interface

FiatEcuScan - Check!
VagCom Cable - Check!
Diagnostics Knowledge - Er.... Houston, we have a problem

 

[Deckchair5]

Ha! That still puts you ahead of most back street garages