What would the symptoms of your stock O2's failing be? I'm getting mildly erratic in closed loop only, sometimes constant light throttle AF = 14.4 then sometimes AF = 16.5 and stuttery ...

Anyone?

 

It'll throw a CEL if the sensor(s) are going bad... Otherwise - they either work, or they don't.

 

Yeah, my perma-CEL is not helping me there ...

I'll have a look at the codes tonight and post the results ...

 

If the AF is 14.4, then 16.5, then something is changing air or fuel. Why do you believe it's the O2 sensor that is bad (particularly if both sides read the same)?

 

I don't know if both sides are reading the same because my innovate is passenger side only, however, if the OEM O2 sensors are failing and reading wrong by the nature of closed loop will make it try and add / subtract fuelling to get to what it thinks is the desired AF of 14.7, however my innovate is reading the correct AF and displaying that to me.

I may of course be totally off base, but I think it's a fair assesment ...

 

Your assessment would be correct if the front 02s are failing. But not the rears... The rears are just part of a feedback loop.

 

Good to know because O2 sensors are crazy expensive ...

 

The rears are interchangable from bank1 to bank2 and visa-versa. But the fronts are bank specific. So bank 1 has to go to bank1, and bank 2 has to go to bank 2...

Although you'll need to pull the CEL code to know for sure what's going on.

 

exhaust leak

 

But wouldn't this be audibly evident?

 

Roger, I'll pull the codes and let you all know what's going on ...

 

depends on how bad the leak is, I don't know about yours but my Z is so loud it is some times hard to hear things unless it is really bad, I had a hard time chasing down a leak I had

 

My exhaust is only 2.5 inch and with the turbos is super quiet in closed loop, and for it to mess with the AF it would have to be pre-O2 sensor which would in theory make the leak loud ...

 

O2 sensors get lazy with age and can cause a lot of different problems.What i mean by lazy is they switch hundreds of times a minute to adjust a/f and when they get lazy the switching gets very slow to respond.If you have over 50,000 miles its not a bad idea to replace them as the exhaust heat just wears these things down.

 

I have 38k on the car, 36k being boosted, the last 13k being TT and pretty rich, I'll check the codes and plan on replacing them anyways ...

 

Code is :-

P0430,TW (Two-Way) Catalyst System, Bank 2

Now this could be one of the following :-

• The catalytic converter is no longer functioning properly
• An oxygen sensor is not reading (functioning) properly
• There is an exhaust leak

Well I know the catalytic converter is no longer there so that rules out #1, so I'm gonna go ahead and replace both manifold side O2 sensors just for kicks ...

 

Non-foulers would fix your issue

 

I would usually tend to agree with you but given the other wierd behaviour that I am seeing ... when I clutch it the AF swings about trying to find 14.7, I'm definately getting much worse gas mileage recently and this wierd stuttering ... I am convinced that my O2's have gone a bit senile and need replacing.

Yes, this won't get rid of the CEL (because my front and rear readings are effectively 0 delta) and the non-fouler would help with this.

I'll get it seen to early next week and let you all know ... thanks to everyone for their opinions and advice

 

So, how hard is it to replace the upstream O2s with everything installed?

 

Pretty much a pita.