MSD A/F Tuner

You can get a cheaper version from Autometer (mine was $55)... They splice onto your narrowband factory O2 sensor and relay the signal that the ECU sees. I like my autometer guage a lot... It's not very accurate like a wide-band O2 setup would be, but it's a fairly good guesstimation of your A/F ratio as the ECU sees it... You have to accept the fact that EFI cars will stay bouncing around on the A/F scale while in closed loop mode (normal driving). You only get helpful information at wide open throttle, when the ECU goes into closed loop. I use my autometer with a Pro-M MAF Tuner, and I can actually adjust the A/F ratio to some extent from the cabin of my vert. Get one of the Autometer guages, and if you don't like it, you won't have that much invested anyway...

Are you talking about this device?... If so, yes it's just an indicator. You can get one from Autometer for $55... A/F ratio meter.

http://store.summitracing.com/defau...ord&searchtype=both&part=msd+air/fuel&x=0&y=0

Sorry man, I linked you to the wrong page... Yeah, your link above is what I meant to link to. And yes, it's just an A/F ratio meter, and not a very accurate one from the way it looks. It just tells you whether you're rich or lean, but doesn't show a good scale of HOW rich or HOW lean. I'd go with the autometer if I were you. The reason that MSD device costs so much is because it comes with a heated O2 sensor, and has to have a heating control circuit. Since you already have an O2 sensor on your car, you can buy the Autometer product, and get a better product for less money... Just my opinion...

You can adjust your fuel pressure, and see a difference in how rich your car is at wide open throttle with the Autometer unit. At idle and regular driving speeds, you'll see the Autometer jumping around because the ECU is trying to adjust for a stoichiometric mixture. That MSD would be total garbage if you ask me... It only has two indicator states, rich and lean...