Dan,

I'm away from home for the holiday weekend d ATM. And there’s the very real possibility the builder has already addressed the issue when he replaced the connector on the harness for the Merc connections. I’m just asking questions so I can properly address the issue when I get back.

Thanks. Brad.

One more tuning tidbit, do NOT allow any compensation. learning to occur at idle , set minimum tps to at least 2 if not 3% and I usually go 200 to 400 rpms above idle too because no matter what holley says about 02 placement vs tip, a 4" ID exhaust ALWAYS seems to false lean a little at dead idle and the holley will keep adding fuel because its off target, Smitty

Fair point here. 4" diameter for an idling engine would pretty much appear to be atmoshere. The exhaust flow boils about bringing air upstream.

My Yamaha R1 on a high idle, would shoot slugs of exhaust out 10ft. Insane how much exhaust energy and a slug of air mass can have. It was also very random, as the pulses moved about.

I run 10 02s on my dyno, 11 when running most holleys and you can see the cylinder 02s getting richer and richer at idle while holley reads off target lean at dead in tailpipe trying to keep adding fuel if not kept out of learn until rpms pick up even fully muffled. Hot rods, vehicles shw up here with aftermarket efi to be "tuned" that have added so much fuel customer can keep it running to get off the trailer, oil full of gas, plugs killed, chugging

Smitty, Tartilla,

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O2 Sensor Bung

Does this change the context in regard to the false lean?

Thanks. Brad.

You're a ways away from the transom. 3" risers?

The O2 sensor is a bit closer to the exh port than what most O2 sensor manfacturers would recommend. But also at the collector merge point. It's likely more a heat factor, and guys that run late timing or poor atomization...a lot of the A/F charge is burning in the port/pipe.

Smitty would best know what would be sufficient. Many ecx tails have the O2 sensor well down stream, vloser to atmosphere that has an easier time coming up the pipe. Reversion of air, not just water is also happening.

Dual 3" pipes will support a lot of HP dry, and less wet of course. That's with effectively zero pressure restriction from the pipe size.

Brad
where you have it,it will work.would have liked it more towards the middle of the adapter in reference to the outside 90° pipe.

Sutphen jogged my memory that you fab'd up the O2 sensor bung plate. One of the specs for install was a 10° angle down. Something like that. Likely to drip off any condensation and moisture.

Sutphen,

I put it where I could put it.

i can tell you, by observation of the software, the WBO2 is working beautifully.

Thanks. Brad.

Tartilla,

Somewhere here on OSO is a thread by Eddie Young, where he details how he installs an O2 bung in the side of the Merc elbow, and it’s pretty much exactly where I have it in my setup, relative to the top of the manifold, and I believe he has it pretty much square to the exhaust path. Mine is rotated around the axis of the C/L a bit, just because it was where I could squeeze it in there. I realize I’m probably getting a lot more reading from a particular cylinder than a general exhaust charge, but it is what it is.

Thanks. Brad.