Mint87RX7

ive been searching but the search on here wont recognize af, a/f so its realy hard to find. i know that the black wire is shielded near the o2 sensor so its best to connect the guage near the ecu. i have the carpet pulled back ready to splice but need to know what wire is the o2 at the ecu?

Mint87RX7

found it, sorry.

Mint87RX7

well i have it hooked up and it lights up. i drove my car untill it was completely warmed up and the entire time regardless of throttle the guage read full rich. does this mean:
1. I am running crazy rich all the time
2. I need a new o2 sensor
3. I hooked it up wrong
Before i go take my carpet out again i want to make sure i know what the problem is

FC_DRIFTER

I have the same problem. My only guess is that its the O2 sensor. I'm looking to get a new one...maybe that'll fix the problem.

WAYNE88N/A

You are checking it out at engine loads other than idle, right?

Idle is ALWAYS rich...

FC_DRIFTER

At WOT what should the proper reading be? Stoich? Mine is leaning towards the lean end when I am at WOT. But yeah....my gauge reads fully rich when I am at idle or at a cruising speed without accelerating.

WAYNE88N/A

Hmmm, at cruise she should be bouncing back and forth at stoich (whatever that is on the gauge- it's .4 to .5 volts on a meter).

At WOT she'll jump around a bit- first go lean, then get rich as the secondaries kick in, all the while attempting to stay around that stoich point...

NZConvertible

Nope, at WOT it should stay full rich. The ECU is definitely not trying for stoichiometric mixtures when under load. And the mixture goes rich because the ECU has increased the injector pulsewidth, not because the secondaries have kicked in. There's no sudden change in fuel flow when they do.

Mint87RX7

mine reads full rich at all times: idle, wot, cruise, decell, reverse, upside down. and what is stoich?

NZConvertible

Where and how is the signal wire connected?

A scoichiometric mixture has the perfect ratio of air and fuel for complete combustion. For petrol this is 14.7:1 by mass.

Mint87RX7

i connected mine at the ecu harness, pin 2d. if it was a bad connection what would the guage read??

NZConvertible

A full rich reading means the gauge is getting a 1V (or higher) signal. Try reading the voltage at the ECU while the engine is running and fully warmed up (after a drive). It should be under 1V and varying as you rev the engine. If this reading is okay, the gauge is bad.

Mint87RX7

thanks for the info, ill check it in the morning. do i just hook my multimeter up to pin 2d and ground the other end?

NZConvertible

Yep.

Mint87RX7

OK, i just put in a new o2 sensor just to make sure that wasnt the problem. before when i had my A/F guage hooked up, as soon as the key was in the ON position the guage would light up showing full rich. now with the key in the ON position it does not light up, so the first question is: Is it supposed to light up with the key in the ON position or not untill the car is running and warmed up. my multimeter shows no voltage reading at this time too. I have not started the car yet since installing the o2 sensor.
once i start it up and get it running, i understand that it should be reading between 0-1V and while cruising it should bounce around .4V
I also need to know if higher voltage means Rich or Lean, so i can figure out if my guage is broken or my car is actually running fully rich at all times.
And any details on what kind of readings i should have at different time like idle, wot, decel, cruise and such.
the pic is to show how i have it set up, its dark out so i have a strap light on the multimeter. thanks for any info!

PS. how do you put pictures in the text instead of attachments??

TO4E-SE

a wide band can give you a much more accurate reading but of course there is the price difference . on the other hand many many engines have been blown even though the almighty a/f guage has been pegged on the rich side when this has happened . thats why you see more and more guys invest in widebands and run them full time . FJO makes one that looks just like the autometer with the semicircular l.e.d lights runnin across the top but has a number screen in the middle as well . will run you about 300-400 bucks for it but well worth the price if you plan on extending the life of your engine . spend it now and make it last or wait till it she blows because you didnt want to shell out 400 bucks . beats shelling 1500 for rebuilt engine . just my 2 pennies

Mint87RX7

i was just wanting a general idea of what my engines doing, i know all this a/f guage is is a voltmeter. my car has been stuttering at high rpm. it stutters differently depending on whether i have the 5/6 ports and vdi open, or just the vdi, or just the 5/6 ports. so i wanted to see what its doing.
if you havent read the thread please read my last post on the first page to see if you can help

Mint87RX7

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HAILERS

I know nothing about the silly gauge.

I know a touch about reading the stock 02 sensor with a digital meter.

On a stock, everything in place engine, at idle it should be reading way low. Such as .01vdc or other ridiculous figure.

If you don't have a airpump/acv up and running, then at idle it will read rich. Such as .65vdc or .7vdc

In either configuration, while driving at a steady speed, it should read b/t .4vdc to .5vdc. Actually jumping b/t those figures or numbers CLOSE to those figures.

At wide open throttle, it'll probably read something like .8vdc to .9vdc.

I've never seen a 02 sensor put out anything over 1vdc.

There is a free onlin factory service manual available for downloading. The url is on this site.

Mint87RX7

well i just took it to test it after fully warmed up. I do not have air pump/acv and at idle the guage doesnt even light and the voltmeter reads nothing.
at steady speed, the guage will show either nothing or full lean. the voltmeter will show roughly .1-.2V
While under LIGHT accelaration, the guage will bounce back and forth like it is supposed to at steady speed, same with voltmeter
at wide open throttle im reading about .8v, at 3800 WOT it drops to zero then back to .8v(ya i cant find the grounding problem) at 6000 and up it will read .9v and then start bouncing from .3v to .9v untill 8000. above 6k i can feel it bucking and stuttering.

Do you think any of this could be related to timing? before i did s5 uim/lim swap my car ran great up to 8000. after the swap I relized my timing had been advanced as far as it would go the entire time so it was put back to stock specs. now i am having all sorts of problems with idle and high rpm. anyone have any ideas on where i should start?

Mint87RX7

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