Derek10AE

Ok heres my situation guys, I went about installing my new autometer fuel/ratio gauge in my 88 TII exactly as the instructions told me to. After hooking up my 12v power wire and finding a good ground I moved on to the final step which was the signal wire. I hooked the signal wire up between my O2 sensor(which was also replaced today) and the PCM as shown in the instructions. Started my 7 and waited until the exuast warmed up to over 600 degrees as stated in the directions. After a good ten mins. of waiting nothing. I played around with all of my connections for the next hour and all I was able to figure was that if I have the O2 sensor hooked up only to my gauge I get a reading, but when it is hooked up the way it should be with my stock wire going from the O2 sensor to the computer and my signal wire spliced in for some reason I do not get a reading. What might cause this to happen?
Any help or suggestions are greatly apprecited!

thanks, Derek

turboconv

I'm sorry this probably won't be any help but I have the same gauge and it works great. But, I bought the O2 sensor with the gauge and welded in an extra boss in the exhaust. I dug out my installation instructions and saw that you can supposedly use the same O2 sensor for the car and the gauge. Since the voltage on the O2 sensor is only running around 0.5 volts maybe it is having a problem powering both the car and the gauges? My only other suggestion is use a voltmeter when the O2 sensor is plugged into the car and running as normal and check the voltage on the line where you were tapping into line. Maybe there is a problem with the cars harness or computer? I hope not. Have you checked the trouble codes for an O2 problem? Just some ideas since it should work as you have it hooked up and it looks pretty simple.

fc3s.org

You know at idle that the A/F gauge doesn't read anything right? What you mean by it isn't showing anything is when you push in the accelerator right? I have 2 of them, one in the Project 86 and one in the 91 vert, both are hooked up the same and both work the same. The wire from the gauge is just tapped inline with the stock wire on it's way to the ECU.

snoopster76

I first hooked the ground up, then the power wire to ignition lead. I got one green light all the way to the rich side when key was on, then I hooked up the O2 wire, it still read one green all the way rich. Zipped tied everything up, now i get nothing. I have tocheck all connections again.

Chris Ng

The autometer guage will show full rich whenever it doesn't recieve a signal from the o2 signal line..
The o2 signal line (engine side) is shielded.. ie: there is a bit of shilding between the actual signal line and the insulation coveriing around it.. you have to make sure that you have a good connection around the actual wire and not around the insullating layer..

MasteRX

If you are getting no LEDs lighting up, then another possibility is a lean condition. If the mixture is too lean, then the Autometer A/F won't show anything at all because the signal is out of range. This would be an extremely lean condition though, so much that you would probably be having detonation problems and such. I would bet that something is not getting power or the signal isn't reaching the meter. OR, the meter is bad.

snoopster76

i was hooking up the power lead, but i hard wired it to elimanate that, but maybe when I was ziptieing everything, i could have puuled it out. Too damn tired to work on it right now.

dcamcoTII

Is the guage supposed to be really erratic? mine runs stoich then when i shift it goes crazy all over the place.

1.3liter_of_power

Only during open wide throttle (throttle opening greater than 80% as idicated by the throttle position sensor) the a/f ratio will be forced rich by the (PCM) for maximum power. Since the oxygen sensor is very accurate and sensitive at the stoich a/f ratio, it will cause the a/f meter to bounce back and forth rapidly. A very small change in a/f ratio cause a large change in the o2 sensor voltage. This rapid cycling is normal when the (PCM) is in a closed loop and trying to maintain a stoich a/f ratio.

Spvolt10- Did you hook up the red wire to a 5 amp fuse that comes on when the ignition switch is on.

I went to the fuse box, right by the clutch pedel, then I turned on the ignition and got my test light and started pulling fuse's that the car does not use. Found a 5 amp fuse for curise control or (ABS) don't remember which one and the light came on to that fuse, . what I did was went and bought a 5 amp fuse then hooked up the red wire there, then to the 12 v ignition.

At idle, the lights on my a/f gauge show's two yellow's, right before the green and stay there. and they stay that way all the way thro the rpm range. hope this helps.

91na,
intake,exhaust, S-AFC:p

dcamcoTII

Should it be hitting all the way lean when a shift and the quickly hit right back to stoich when i get back on the gas?--also, mine never hits rich, is that bad? it runs about 4 stoich lights all the time then when i shift it goes way lean and back up--is this normal?

HAILERS

Might help http://www.autometer.com/hp/index.html its the Autometer home page and under FAQ there is a discription of the working of the gauge. Might help, might not.

1.3liter_of_power

decamco TII- What mods do you have on your rx-7 and how much boost are you running? Pretty sure that is normal about running lean when you shift and when you let off the gas. Mine does the same thing when I let off the gas pedel, but the lights go back and forth from yellow to red which is normal, if they stay at red then your runing to lean. Are the yellow lights closer to the red lights or the green lights? Do you have a stock blowoff valve? Could be that the valve is noting letting out the all of the boost during shifts. Some how, I dought this is the reason for running lean during shifts, then again, you never know.

TonyTurboII

dcamcoTII, you need to upgrade that fuel pump!

dcamcoTII

My mods are as follows: Full RB, FCD, magnecor 10mm wires, and a homemade atmospheric BOV
I am hitting about 9 psi max
I ordered a fuel pump when i got the guage but they told me my card # was invalid, prolly typed it in wrong. But i figured i would get the A/F guage in and see how i was running before i spent the 130 and upgraded the pump. Even with these readings do i need a fuel pump. I definatley plan on one before any more mods.

TonyTurboII

Is it closer to the red, or green? And how far away is it?

dcamcoTII

its about 4 lights dead center--and when i get on it it manages to hit 1 green light.

TonyTurboII

That dosent sound bad. If it ever starts rolling back, let off. Youll know its time get more fuel. You could also check to see how much voltage your getting at the fuel pump, and if its low you could re-wire the stock pump.

Chris Ng

These are my opinions and based on autometer a/f gauges and turboed FC's:

At idle, most T2's that have their airpump's and other emissions equip will read on the rich side.. sometimes after idleing awhile it will drop down to 1 yellow 1 green or there abouts..

when in closed loop mode (as mentioned prior, depends on engine load and throttle position) the guage will bounce back and forth quickly from lean to rich.. if you notice that the backand forth bouncing starts to slow down over time, your o2 sensor is starting to fail.. it should bounce back and forth rather quickly..

During acceleration your guage should flip over to the green side of things..

when you let off the gas, the guage should drop right to red but most likely it will read nothing on the gauge..

It is normal for your gauge to bounce to red and back to green during shifts (You are momentarly removing load from the motor and getting off the gas.. increasing the intake of air and going lean.. it's perfectly okay to go lean when you have no or little load on the motor)

You should be within 2 bars into the green when you are at full throttle acceleration.. Please do not think that because your gauge is showing you at stoich (yellow) that you are safe.. 2 bars into the green roughly translates to about 0.8V o2 sensor voltage.. running stoich (0.5V-0.65V) is perfectly fine and shows "perfect" combustion when off boost.. however you are on the ragged edge when at full throttle.. 0.8V - 0.85V is generally acknowledged as the "safe" zone for on boost WOT operation giving you the best safety and power.. anythign above 0.9V (aprox 4-5 bars green) is regarded as running too rich and robbing you of power..

If you are in fact reading in the yellow while on boost, I would suggest you turn your boost down, stay off boost, or get some more fuel.. you are driving a timebomb...

With all that said and having scared you.. It is entirely possible that your gauge is reading low because of poor grounding.. Here's a quick and easy test.. go for a drive.. get the car up to operating temp.. now park and idle.. take a look at where you a/f guage is reading.. now turn on yoru headlights.. do the readings go leaner? If so your a/f guage is not grounded well.. I would suggest you ground your a/f guage straight to the battery.. I will almost guarentee that you'll find yourself reading richer after doing so...

Grimlock

my a/f gauge used to bounce back and forth before i put my rp fcd, now that the fcd is installed the a/f gauge doesnt bounce back and forth but it stays rich thru boost and stoich when cruising it just doesnt bounce back and forth anymore....is this ok, maybe my tps is $%* up!!!!

dcamcoTII

Looks like my problem is bad ground, that would explain why it runs richer in the daytime, lol!! So all i need to do is bring the ground out to the negative battery terminal??? also, could i just run a wire inside the car from the battery and use it as a universal ground??

dcamcoTII

ran a new ground from the battery--im now running way rich--everyone says my car is in danger of leaning out, but from my reading i am nowhere close. Does this mean there is something wrong w/ my car???