[brucepick]

Thanks theunchosen.
I think there's good sense in your notes.

It's pretty odd really - LB causes the cat to cool off and apparently causes the block to heat up. I'd assumed the hotter lean combustion temps were just local in the cylinder and the cooling system would keep the rest steady at the usual temp. But maybe not, if it runs very lean at wider throttle.

A couple weeks ago I took off all the lower grill blocks and only kept the full upper grill block I'd just built. In warm weather it's been mostly doing LB with no issues. In cool or rain it doesn't want to stay in LB.

Left side has a/c condenser, with cat and engine behind that. Right side has radiator, and tranny behind that.

I'm thinking, restore most of the blocking on the side where the cat is. Keep the cat warm. I'm sure there's a temp sensor inside an oxy sensor that talks to the ECU. In summer I need to leave a bit of air path open there because the a/c condenser is on that side, it needs some air flow.

And, in consideration of what you wrote, keep the air path on the other side - where the radiator is - open. So the rad can keep the engine cool when it gets hot in LB.

Still I have to say, just going from recollection, I think it mostly is cranky about LB in cooler or wet weather. I can test if blocking up the cat's cooling air flow gets me more LB.

Thanks!