Lambda sensor issues help

[Andys60]

So I've got an issue with both pre and post cat 02 sensors....in fact the post cat 02 sensor is shot for sure....
My problem is I'm unsure if the pre cat one is knackered too!!! I'm gonna put some stills of freeze frames on and I'm hoping somebody can help me out...
The problem is the short trim fuelling is always in the negative 20 odd % extremely rich and never comes the other way??? Voltage is perfect fluctuates within the perameters as it should... Anybody got any thoughts please...
Pics to follow

 

[Andys60]

 

[Andys60]

 

[Andys60]

 

[Andys60]

 

[Andys60]

Any body got any ideas cheers
Andy.

 

[Andys60]

Sorry about the same stills lol

 

[Andys60]

So knowbody got any thoughts?

 

[da rok]

the lambda sensors are only there to measure the oxygen content, so if the readings look whack, its not always the sensors at fault, can be leaks on the exhaust or a number of other engine related problems, normal readings should go from around 0.3/0.4 volts to 1 volt max (normally 0.7/0,8) and down again, a good reading would do this cycle every 1-1.5 seconds... if the sensors are old then replacing them could do the trick, my sensors were toast after 10 years and were shorting out blowing my 30 amp ecu fuse. its easy to pull them out, so check their condition visually, look for broken wires etc, you can also bench test them with a volt meter to see of they reading properly.

 

[MicKPM]

You need to graph the results to really be able to see what's occurring... Numerical figures update too fast to see/be useful

 

[Andys60]

Wish I had access to some software so I could graph it for sure..... Cheers for the input guys....
My only I said really is the rich rich rich negative condition on the short fuel trim? Never goes any where near lean....
As for the voltage on the o2 sensor it acts like any good sensor stays within its limits voltage wise and really quick reacting as you would expect.