So I took my Z in my sig out last night (first time in 19 months). I made sure it got an oil change, new gas, and had been running properly before opening it up.

When I did open it up I made sure my meth injection was working, and I paid close attention to the wideband AFR gauge to make sure I wasn't running lean.

I believe it was tuned to have around 11.5 on the AFR at WOT. And for the most part that it where it was. However, there were times it dipped down to 11.1 and I saw it hit 10.9 once momentarily.

What is the ideal AFR? At what point would it be dangerously lean where I would need to get out of the throttle?

 

I would say that is fine. There are ALOT of factors that go into what afr would be a problem, generally I wouldnt want to see it any leaner then low 12's.

 

Most FI guys like to keep afr's in the 11.5-11.7 range of course there is some give and take in there according to timing, internals, fuel type that kind of thing.