Air/Fuel ratio meter question????

take the gauge out and throw it in the trash....its worthless. buy yourself a wide band o2 and it will give you an exact number for your a/f ratio. wide bands run $300ish and up. with that blower on there and a 347 if you dont have your car dyno tuned or at least get a wide band o2 you are asking for trouble. your a/f ratio is probably way off.

The A/F gauges that use the O2 sensor signal will jump all over the place. The reason is that the O2 sensors "switch" between .2 volt lean and .6 volt rich with a curve that looks like the drop off a high cliff. The curve is almost straight up and down, so the voltage shoots from .2 to .6 and back down . again 2 or more times a second at cruse. You won't get much useful information except when the mixture is extremely lean or extremely rich, there is no middle ground.

Use 43 (Dark Blue/Lt Geen wire) or pin 29 (Dark Green/Pink wire ) on the computer. Use Wire tap-ins from Radio shack P/N 64-3052. The computer is located under the passenger side kick panel. That keeps you from having to crawl under the car and make a weather proof splice in the wiring. You can use either one, or run a SPDT switch and use both. Then you can use the switch to select which side to view.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/t...91eecPinout.gif


AutoZone wiring diagrams

http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for 79-88 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-98 model cars

get yourself another 02sensor and a welt in bung so you can run a stand alone type setup for that thing. see, the computer reads the 02 sensor via voltage. so therefore if you piggyback another mechanism to it you will divide the signal by half becouse it has to go in 2 seperat directions. so now your gauge nor your computer will read it right

NUTCASE said:

get yourself another 02sensor and a welt in bung so you can run a stand alone type setup for that thing. see, the computer reads the 02 sensor via voltage. so therefore if you piggyback another mechanism to it you will divide the signal by half becouse it has to go in 2 seperat directions. so now your gauge nor your computer will read it right

Click to expand...

Not exactly right...
The signal from the O2 sensor will power both the computer and the gauge if the gauge has a high input resistance (impedance). That's why you can use a high input impendance (1 Megohm or more) DVM or multimeter to measure the O2 sensor output voltage. Measuring the sensor output is useful to determine how well the O2 sensors are working.

The problem is the O2 sensor signal isn't suitable for anything but the computer to use - see my previous post as to why.

I was just going off my experience of trying to jump factory water temp and oil pressure gauges

If you're attempting to tune via a narrow band sensor then you're spinning your wheels. The narrow band sensor is in capable of giving you any valuable information other than a stoich AFR of around 14.7 (provided that the thing is any where near being properly calibrated). Taking into consideration that you're using 42lb injectors and a 90mm meter of some sort, I'm lead to believe that you want to want to try and use this thing to get a grip on your air fuel ratio. I talso comes to mind that the ideal AFR for the setup is probably going to be somwhere in the 12 to 13 range (not knowing the rest of the combo, this is just a guess) for maximizing HP. If that's the case, those AFR ranges are not withing the narrow band sensor's range and you will certainly get readings from it that make no sense whatsoever. Your options the way I see it are to get a wideband readr and sensor or have the thing dyno tuned. Once complete and if your final AFR ends up in the 14.7 range then you can use your narrow band sensor and gauge to see if it's still there. That's about all it's good for.

One other small tidbit that I neglected to mention. If it's a wideband sensor that you're attempting to run a wideband gauge off of, well... the gauge will in most cases not operate correctly either. The after market guages that I've seen so far are looking for a narrow band signal to convert into a reading. You will still need an AFR meter that's capable of converting that widemand signal into a narrow band signal in order for the gauge to indicate anything resembling usable data. I use an Innovative LM-1 wideband 02 reader. It has a 1V narrow band output specifically desigend to convert the wideband sensor sensor reading to a narrow band output that an AFR gauge is capable of using. Either way. You'll need an AFR meter.