So I know that narrow band A/F gauges are unreliable but latly my has been saying that I'm running lean in boost sometimes. Most of the time it runs perfect on the gage but other times it runs lean and it also feels like it's lean (less power). No knocking yet but I'm a little concered. Any idea what it could be. Bad fuel pump, FMU, ???????

 

NBs are horrible. You could be running rich, you could be running lean, no way to know.

FMUs can sometimes be a bit "flakey". My vortec seemed pretty reliable, the BEGi would sometimes take a second to catch up.

 

Mine is a 1.8 NA. Don't I have your old vortec? I have a 6:1 disk in it right now. Is weird. One time it went in the red then popped back to green. I would just ignore it but like I said I can feel it lack power at times.

 

this fucked with me for a while to, I think when he said "NB" he means narrowband as opposed to a wideband, not NB miata...

 

Lean on a NB gauge should still mean anywhere from 14.7:1 to 19:1, i'd want to figure this out.

 

Also, lean on a NB could be rich in reality, and rich on a NB could be lean in reality.

 

the NB signal will display rich (10-14.6:1) from 1.0-.8v, then stoich from .799-.2v (14.7:1), and lean from .199-0v. (14.7-19:1)

correct?


something like this:

 

Sorry I get NB now. So it is something to worry about. Any ideas.