tosha
Well-Known Member
Thanks a lot. The problem that I have is that I started getting P0430 errors, but my dealer keeps insisting that these are tune ralated and they are working with Roush on analysis and getting an updated tune from them. One update that they installed recently did not really fix anything. As long as the cat is not melted and I don't end up with a failed engine, I'm ok to let them figure it out. Thinking about it more, it seems that datalogging won't help me much, as it would show same conditions that already lead to CEL. What's the best way to inspect physical condition of the cats? Does it make sense to get one of these inspection cameras and use sensors holes to do a visual inspection? I want to double check what I'm hearing from the dealer.The way I understand it,
The front O2's has a rich/lean switching rate that is directly from the engine operating conditions. Easily seens in the lamba PID. It changes rates with load and RPM. This switching rich/lean "depletes and fills" the catalyst of stored oxygen. Oxidation and reduction cycles of the three catalyzed reations.
To test the catalytic converter, they are concerned with its oxygen storage capacity. below a threshold of oxygen storage, and it gets reported as failed/ ineffecient.
To test this, steady state conditions need to be meet for long enough to run a test with fuel being controled by the rear O2 sensors. Theres a few steps and it will abort in the middle of any of them if conditions are not maintained.
When it controls fuel from the rear sensors, the switching should be slower the more oxygen the catalyst can store slowing the oxygen signal(transport delay) from reaching the sensors, so they overshoot lambda more than the fronts would. If this overshoot isn't enough, the catalytic converter is considered failed/ ineffiecent.
Attached is a picture of what im talking about. When they start to fail/ become ineffecient the switching becomes less noticable in the logs. Probably best to just wait for a MIL light and let the ECU do its job, rather than comb logs looking for early signs, which would actually be harder to notice the more ineffecient the catalytic converter becomes.
Of course if its temperature related and melting failure, you probably wont see signs of it in a log until after it happens and the car sounds, smells, and runs bad. Some failures they will crack first, then melt, but as far as I know when they melt, its quick with out advanced warning.
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