Brantley

I am installing the gauge below the radio. Hooking up the power and ground wires are no problem, but where should I go to hook up the oxygen sensor wire? The wire doesn't appear to be long enough for me to feed through the firewall to hook in to the oxy sensor wire. So, it seems my only options is tracking down the wire for the oxygen sensor that feeds to the DME. Does anyone know the color code of the wire going to the DME so that I can splice in to it with in the cab?

Any other suggestions?

Thanks!
Mike

TRACKIN951

It is a thick green one. Do a search, I cant remember the exact pin number... something like 24 or 25ish

Brantley

I did search, but the posts I found didn't seem reliable... So, I am afraid to cut the wrong wire! I'll continue looking though previous posts, and for the thick green wire.

Thanks,
Mike

KuHL 951

It's the thick green wire with the shielded jacket, at least on my 86 it was. Not sure if it was necessary but I reconnected the shielding, where it got cut, with copper foil, just in case it was a grounded at one end only.

Brantley

Thanks guys... It is the big green one (though, there are a couple big green ones) and it is pin 24 and shielded.

Now, I know these are not the most reliable for judging a/f for tuning, but the car is completely lean. After letting it warm up the lights went further lean till they were off the gauge!

Off to research what can cause a lean condition....

Thanks,
Mike

Driftomagnifico

The gage is typically based off a 1v signal from the narrowband 02 sensor. It will only tell you where you are in relation to roughly 14.7:1 based on a few variables. Meaning if you are re-fueling the car behind you by running a 8:1 ratio it will only show "RICH", if you have 12:1 it will show the same "RICH" condition. If you are running 14.3:1 then it will show slightly "RICH" as it approaches the voltage spectrum. The same is true for the "LEAN" condition.

When you are cruising the meter should be near the middle of the spectrum at normal cruising throttle. If you go WOT then you should see nothing but "RICH". If you see "LEAN" or anything near stoich at WOT you need to have the car ran with a proper wideband 02 at a dyno or on the street to verify the condition.

If you let off the gage should read "LEAN" until you reach idle range. Then it will begin to cycle back and forth depending on the 951's 02 setup.

Not to rain on your parade, but overall the gage is pretty worthless hence the name "Disco Gage" that many apply to it. You can always sell it and use the money towards a proper wideband 02.

SD Porsche Fan

You have the Vitesse chip have you also upgraded to a 3 bar fuel pressure regulator? Any fuel leaks? When was the O2 sensor last replaced? Have you had the injectors cleaned/rebuilt?

KuHL 951

You might want to check for vac leaks as your first test. The old vac gauge test rules still apply, read up on it. It's really amazing what a test vac gauge can tell you if you have the basics down and know how to read the results. Crusty injectors can also produce both lean and rich conditions depending on which mode they get stuck in. Even a narrow band AFR gauge will at least tell you you are leaning out with some degree of accuracy. I would rather be rich than lean so you need to find the problem soon.

Brantley

Drifto - Thanks for the explaination on how it should look when properly functioning... hopefully I get there...

SD - I'm having problems passing smog right now, so I just replaced the Oxygen sensor. I also just got the lindsey racing tuneup kit (distributor, plugs, wires, etc) and installed that at the same time. The injectors appear to be original, but I like your thinking. I should probably send them to witchhunter.com for a good cleaning and reseal. Yes, also have the 3.0 bar fpr. I do not believe I have any fuel leaks.

btw... I am failing the smog check on high NO. From some of my research, this can be caused by high temperature on the cylinder head... So, since I am lean, perhaps that is causing the excessive heat... hmm... ( I have not been back to the smog check since the tune up and new o2 sensor, I will be going this weekend).

Kuhl - Thanks for the advice. I will try that... I just bought the boost tubing from lindsey and have yet to install it. Currently have all of the original boost tubing in place.

Got Me a Porsha

Using search...

Another...

Yet another...

My Personal Favorite...

Summary...
How to install a narrowband Autometer A/F ratio gauge:

1. Install your favorite gauge pod or panel;

2. Open shiny new yellow box and remove gauge;

3. Cut all three wires on gauge soo short that nobody will EVER be able to hook it up;

4. Insert new dummy gauge into panel or pod until you purchase a wideband!

It worked for me! I personally know of three Autometer A/F light shows that failed and caused many hours of needless troubleshooting to correct a/f ratio problems. When they fail (about a year) they induce feedback into the O2 sensor circuit and make the car go very rich or very lean.

The customer disservice at Autometer is just that.

UK952

I like this one (not just cos its mine) https://rennlist.com/forums/showthre...ht=narrow+band
and this one
https://rennlist.com/forums/showthre...ight=autometer
I agree a wideband is better but the narrow band should at least give repeatable results, IIRC asarus did have a bad O2 sensor.
Tony