Originally Posted by DrCharles
I have an Autometer 3579 (analog 2-5/8" gauge) which I find very useful for tuning. For example, I can see the difference between the common pump E10 and no-ethanol gas (about 0.3-0.4 AFR). I couldn't have tuned my Holley 850 without it (IAB, MAB, IFR, TSR, PVCR and of course main jets).

The replacement oxygen sensor that they sell for $120+ is actually a common Bosch unit that you can get considerably cheaper. The major problem with their design is that it is not tolerant of the voltage drop during cranking (it will never warm up and actually start reading). The tech line actually told me to put a switch in the +12v line and don't turn it on until after the engine is started. Which did "fix" the problem. Really great engineering there, guys eyes

A more expensive one (than the Autometer that was over $200!) would have datalogging capabilities that are even more useful. You need some kind of wideband AFR otherwise you are just guessing from ET/mph (assuming you're even at the strip) or trying to figure out if a driveability bog, sag, stumble, etc. is too rich or too lean twocents


Two things, who measures the AFR during cranking? No one.
Why didn't you already have it wired in to a switched in run 12V?
I don't think the issue is Holley's engineering.