A couple of quick thoughts:
Damn! Thank you for the considerable thinking and writing you put into it for me.
Did you mount your O2 sensor between 9 and 3 O'clock in the pipe? 12:00 is the best spot. One of the biggest things that kills O2 sensors is water, especially after a cold start if the sensor is heated all of the way up and the pipes are cold (lots of condensation along the pipe walls in the exhaust). This can be plausible if you're running long tubes and the sensor is mounted in the mid-pipe, because it takes some time for the pipe walls to heat up enough to prevent condensation. If you mount the sensor between 9 and 3, then there is less chance for it to be hit with water droplets, but they can still get picked up by the exhaust flow.
Yeah, I'd estimate it's mounted at about the 2, which is about the best I can do in the mid-pipe. Yeah, I have the
BBK LTs and there's no room elsewhere. Might go to a custom
Kooks setup for the next combo and will keep this in mind.
Do you know how hot your exhaust gas is getting? The only time I've seen properly mounted O2 sensors fail like that is in hard-core road race conditions where the EGTs exceed 950°C at the sensor for a long period of time. This usually only happens when the sensor is located very close to the header collector with shorties. Glowing red pipes would be a good indicator. The other way to get the EGTs that hot would be ignition timing that's way-late, but your car will also drive like a slug with super late timing, so that's probably not the situation in your case.
Can't be that bad back at the mid-pipe, but the heat-sink bung should help with that. No idea if it'll help or hurt the condensation. Timing's too advanced in the mid-range at light throttle, as I hear a bit of detonation. I'm running around 17* base timing on a stock A9L. It's doing great at WOT, though. I will address this soon with my upcoming quarterhorse install.
Have you called Innovate? I remember in the past there were a ton of counterfeit sensors dumped on the market for super cheap and they failed in the 1 to 3 month usage range. It seemed like a lot of the Lambda meter suppliers picked these up at the time. Unfortunately, the aftermarket doesn't have the same quality standards as the OEMs, so you never really know what you're going to get in terms of quality. The counterfeits also included cheap EV1 injectors - there were green-top 42 lbers listed on Ebay for $20 / each. These were definitely NOT made by Denso or Bosch. Both of these parts are rather scary since a failure from either one could take out your engine in short order. I think you made a good move ordering from a reliable source.
Yeah, I don't play around with amazon & ebay. Sometime I will with FB marketplace, but I still try to validate the part with research and close examination. I've all but decided I won't do electronics there, anymore. I've been shafted too frequently. Another rule is paypal with buyer's protection on purchases, but never on sales. Don't care if it's hypocritical. The difference is I won't use it unethically. Thanks for the heads up on EV1 injectors. A while back, before I swore stuff off, I got a set of red top FMS 30-lbs injectors. The bodies match identically, and they came in a rough, old Ford box. I think they're real, but they may be the last set I buy for 2 reasons now. Counterfeits are the first. The 2nd is that I've been reading and chatting with folks who say the more modern high impedence Deka 80's can control low pulse width very accurately, compared to the older stuff. That would allow for E85 in my future, potentially. I might pull out all the tricks one day for a glory run on the upcoming build.
In either case, once you get the new sensor, I strongly suggest re-checking your tune to make sure the original sensor was reading correctly at the time. If it was bad, going bad, or a counterfeit, then you could have some Lambda measurement offset in your engine calibration. A potentially very frustrating situation.
Good luck with the new part!
Put the new sensor and bung in yesterday. Stock tune looks identical. There was no feedback from the MTX-L or its sensor to the stock computer. When I start tuning with the quarterhorse, I will be the feedback mechanism, but I'll also verify the AFR and timing by reading the plugs.
