DIS Failure symptoms?

[XfireZ51]

Originally Posted by scottfab

Sure feels familiar. What side went to 70? I mentioned this before, O2 sensor.

Bad O2 would be consistently bad, not just when cold and at small AE increments.

[scottfab]

Originally Posted by XfireZ51

Bad O2 would be consistently bad, not just when cold and at small AE increments.

That would be incorrect. Sorry. You have to understand the different (many) failure modes of an O2 sensor.

[XfireZ51]

Ok. Please explain and then tell me how it explains the symptoms Lee is describing better than what I think the issue is.

[Funracer]

Originally Posted by XfireZ51

Ok. Please explain and then tell me how it explains the symptoms Lee is describing better than what I think the issue is.

[scottfab]

Originally Posted by XfireZ51

Ok. Please explain and then tell me how it explains the symptoms Lee is describing better than what I think the issue is.

I'm not going to go for "better". I'm going to caution about ruling out the simple things.

First read my previous post on one of the failure modes. (heater) then note the the O2 sensors can behave intermittence from a coating of contaminates on the zirconia element. I suspect the one I had that went bad of failing in this way since it worked fine sometimes then would go "lazy" sometimes. Once the system adjusts to they lazy O2 reporting (uses richer block/trim) then starts working well again the trim will go low) run lean until adjustments happen again.

Best isolation I did was to reset (battery disconnected) and collect data while running down the road. I could see the struggle.
I swapped the two O2 sensors and saw the switch side to side. I was fortunate to have the long leads on both.

We all know intermittent problems are the worst. I say rule out the simple possibilities before going to more elaborate ones. If this car had always had this issue it would be different. As it is I am left thinking it ran well at one time. (mods or no) So look for and proceed to isolate from easiest to hardest components.


1. consistent fuel pressure? (pump issues)
2. O2 sensors ? (intermittent)
3. injector ? (intermittent)
4. Redesign cals

[LGAFF]

Yes, ran fine last year....as noted...and maybe nor relevant, weather was much warmer(cal??)

I agree could be the 02, but it needs to be tuned also