I discovered that the 460 EFI engine in my 1992 class C motorhome is going
to open loop at around 7" to 8" of absolute manifold vacuum (i.e. the O2
sensor indicates steady rich at that vacuum). I would expect the engine to
go open loop closer to 4" or 5" of vacuum when I really have my foot hard on
the gas. Is this normal for this engine, or is there something else I
should be checking?