Best Location for AF Sensor Bung, UPDATE: I got a SS muffler, what you all say now... Options

[913B]

I am going Microsquirt. My current muffler right before I tried cleaning the dust off the part label and it just incinerated is a Dansk 1.8 muffler from what the PO said.
I did have to reweld and rotate tip to exit correctly under the valence.
Maybe it was a bus muffler?

Anyone have any experience on where to place the AF sensor bung, too bad its not on the car to check for clearance/obstruction issues.

I was thinking of welding it on the tail pipe where the black circle I marked off.

I could buy a new exhaust with the bung attached, but this is my attempt at going Microsquirt without spending too much and work with what I have.

Anyone cut one up before and know of a good spot?

Thanks in advance.

Ted

[BeatNavy]

I've been running Microsquirt for a couple of years now. I don't have experience with that specific muffler, but if I had to guess the place you propose is as good as any. I'm always hesitant to drill into the "body" of the muffler for fear of upsetting the internals, and you don't have too many options there. I'm sure others can provide more specific guidance.

Yes, clearance is an issue to be concerned about. Take into account not just the sensor but the cable and the fact that you have to get it all lined up to thread it into the bung. That means you either need more space than you may realize or you have to remove the muffler before installing/removing the sensor.

Running Microsquirt in closed-loop on a type IV can be a little tricky, particularly at idle. Idle AFR numbers can be misleading on our motors due to a number of factors. I initially ran closed-loop using a stainless steel, dual-tip muffler sold by a vendor here. It had the O2 sensor bung pre-installed, presumably in the "best" location. It is a great muffler, but for whatever reason I could NOT get usable AFR numbers at idle. Always showed way too lean and had me chasing my tail for months. Above 1500 RPM or so it was fine and closed loop worked great, but idle was useless.

Eventually I switched to another vendor's muffler, with single-tip, and voila', my AFR numbers at idle were useful.

So: make sure you heat exchangers/headers aren't leaking at the heads. Make sure your muffler is not leaking at the heat exchangers. And don't drive yourself crazy chasing a specific idle AFR or closed loop setup at idle if it just won't happen with this muffler.