Update: Long and Short of it - User Error. Turns out my misfires were in fact due to a melted cat. I likely melted my cats while using the race tune and 100 plus octane fuel. I thought I made damn sure I was using unleaded race gas but perhaps I misread the pump. While I will admit I may have made a mistake, I don't believe APR or any of the other tuners do enough to inform customers about potential dangers with using their race tune. So, if you have a race tune, or if you are thinking about running race gas, be aware that the cats likely can not handle the extra heat and/or most certainly not any lead.
All fault codes are now gone, except for the new o2 code because I replaced the cats with test pipes. Sounds horrible with the stock exhaust. I will be reflashing my ECU back to Stg 2 (with the o2 delete option). Car should pull like a freight train, and especially after adding the new DSG tune with a 7200 redline. I think having had to deal with this problem for the past month ultimately turned out for the best. As long as I can find the right catback exhaust to reign in the screaming Honda the car has become.
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So my STG 2 APR car apparently melted a cat. I never had any indications there was anything wrong. I have VAGCOM and would have pulled codes if there was any indications.
I found out I had a melted cat after the dealer said that was the cause of misfires I had all on one bank. Trouble is in terms of order of events I pulled codes before giving the car to the dealer for diagnosis and had no O2 related codes. Just misfires, leak in air intake, and fuel trim.
Can a cat fail in a sudden catastrophic way? One second everything works great, and the next heavy misfires under load above 4/5k rpm? It just seems unlikely a cat could breakdown so suddenly. And if it can and did, why the heck didn't I have any warning?
Does APRs tune program out the O2 sensors? Basically there was no indications my A/F was out of balance.
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