I would not have expected a dual bank Air/Fuel meter to be $450+. I have been looking at the Fast and the Innovate models. Is there a cheaper dual bank one out there?

This one is not dual channel but I could buy two for the price...what does narrow band mean and would it work? I have four original GM O2 sensors laying around my garage from my 2002 avalanche...are they wideband or narrow?

http://www.amazon.com/MAGNUM-Exhaust...productDetails

Why dual bank? We just put O2 fittings in both starboard tail pipes. For marine, this is close enough. If you have the O2 plugs welded in your tails, you could probably borrow someone's O2 sensors and gauge. They aren't fragile and once you get the fuel set, this toy stays on the shelf.

Actually you want them in the port side pipes. The odd bank of a bbc reads leaner than the even side.

I have two of the innovate mtx-l, they work great IMO and are cheap. I haven't hooked up data logging yet because it comes with a serial port that you have to convert to USB and then somehow get that to work with windows 8. That is my only gripe with the product.

Narrow band only read rich or lean of stoich and bounces around. Wide band is what you want if your going to be tuning. That will show you the actual ratio instead of just rich or lean. The o2 sensors from your avalanche are narrow band and work fine in that application of just stock efi riding around at 14.7. When you tune an engine for performance ( cars atleast) most o the time the best power will be made around 12.5. I hope that makes sense to you.

Lot's of opinions but this is what we tune to. Idle AFR 15-15.5 in gear, midrange (3500-5500 RPM) 14.1-14.3 and 13.2-13.6 5500+RPM (3.5 power valves open at 5500 RPM). The plugs always have color and never any sign of detonation. We use premium pump gas and make 750+HP at 6800 RPM. All this is from memory, might be off a smidgen.....

Had frustrating experiences with the Innovate LC-1. Might have been just a bad unit, but I returned it for refund after a month of messing with it. It kept auto calibrating itself at the weirdest times.

Been using AEM Uego units with Bosch widebands since then. Zero problems. Cheaper than the Innovate also.

I agree that you can get by with one sensor on one gauge.
Bungs in the odd bank tailpipe (well ahead of water).

Tune one motor, make the same changes on the other motor and swap the sensor to it to verify and/or tweak.
Then pull out the sensors and keep them for whenever you make another change that affects your mix.

MC

I have looked at these also and did some reading. They are correct about wanting wide band so you can see what it is at different loads.

I believe one of the popular o2s available is a wide band from Bosch, it is available for 50 to $60, not sure if thread will fit merc. Doubt it. How much do these jump around? Does the meter filter it at all, I always thought they were a 0 to 1 volt output, so a meter is basically a volt gauge? Thought about installing one and take the boat for a spin with someone reading the multimeter! Would it work?

Watching this one

In theory it would. I have a kick ass fluke Oscope at work that would even log it. Just need a conversion or a range.

I have an Innovative and an AFX. If you want, I will send them to you. Use them as long as you need and send them back. Let me know. I still have your address.

You want wide band.

I'm using the Innovate MTX-L unit. Nice gauge, good harness, easy install, data log is great (Win XP Pro), been running it for two years now. It has been invaluable for tuning and engine monitoring, hence I leave it in full time. It was eye opening to see the difference in AFR between VP110 and pump gas.

System uses 5V reference if I'm not mistaken.