O2 sensor, bad idle, and an air/fuel gauge

[symple]

So I installed my a/f gauge the other day. . . I used the same power source as my boost gauge (the cluster of wires on the far right of the instrument panel...used for the head-light dimmer and flip up switch) and tapped the 02 sensor wire on the passenger side. At first, I would only get one green light all the way over on the 'rich' side of the gauge. Why? Who knows.

I redid the connection to the 02 sensor, turned it back on and the gauge lit up from red though yellow, and to green, one LED at a time. Then it stayed at the far green light again. Again, Don't know why.

When I shut the car off and tried it again, i got nothing. Not one light.
What am I doing wrong?


I decided to change the positive connection to the fuse box thinking that might help. That's where it is now. I forgot exactly which one I used, but it's one that only has power when the key is at the 'on' position. I tested a 5 amp fuse in it first and it didn't blow it.

On a side note, I used my volt test light and the o2 sensor wire on the passenger side was dead.

My car refuses to idle after it's warm. Could any of this possibly be related?


Any suggestions on how to get this working?


Thanks,
Symple

 

[DSM90AWD]

When hooking up a multimeter to the Pass-side O2 sensor port set it to 1V. During Idle or lowspeed operation it should hunt from 0V to 1V (closed loop).. also shown as flikering of lights on the Air/Fuel meter. If it does not do this your O2 sensor needs replacing.

When on the go-pedal (open loop) the readings should be near static in the .88 (lean) to .94 (rich) range.

I've never put much faith in those AFR meters as O2 sensors for DSMs are the least accurate POSs I've seen. I can run .88 some days and .94 on others with no knock.

IMO... EGT and Knock Sums/Timing are the best resources for tuning.

 

[symple]

Thx for the info. I'll order a new sensor ASAP. I've also heard that A/F gauges aren't worth it, but I pretty much just got it for the light show.

Do you think running waaay rich would kill the car at idle too?



Thanks,
Symple

 

[DSM90AWD]

Originally posted by symple
Do you think running waaay rich would kill the car at idle too?

Maybe.. if the plugs are fouling.

Couple things also to check:
- Remove ISC and clean out the w/carb cleaner & q-tip
- Check for Boost Leaks (pressure test intake)
- Base timing w/ Advance grounded s/b 5Deg BTDC
- Base Idle s/b 750RPMs with all accessories off (adjust BISS)

I pretty much just got it for the light show

Nothing wrong with that

 

[1gCTgSx]

Are you sure that you tapped into the signal wire to the ecu and not the 12v wire that powers the 02 heater? Tapping into a 12v source for a gauge that is supposed to read between 0.0 and 1.0 volts would definitly show you a rich condition. Anyways, use a voltmeter or a test light or something of the sort and probe each wire, theres two grounds, a 12v, and the signal wire.

 

[symple]

I used the single black wire with an orange stripe going down it on the passenger side. It's a 10 gauge wire I think.


This Page says that there was nothin plugged into it, but mine was connected. However, in that bundle of wires under the dash is a solid white connector with three smaller wires going into it. It has nothing conencted to it.



--Symple

 

[DSM90AWD]

Originally posted by symple
I used the single black wire with an orange stripe going down it on the passenger side. It's a 10 gauge wire I think.


This Page says that there was nothin plugged into it, but mine was connected. However, in that bundle of wires under the dash is a solid white connector with three smaller wires going into it. It has nothing conencted to it.
Symple

This wire should be a small gauge.. 18-22 (not 10ga) and should have a white female connector on it.

There should not be anything plugged into it unless a prev owner did it.

 

[symple]

Ok, so everything is hooked up. I redid the wiring and took the o2 wire from the gauge off that thick ass wire. The only other available plug with nothing in it is white and has three 18-22 gauge wires coming out of it. The plug itself is capped. It was taped to the side of the bundles like one of the guides said, however, it has 3 wires coming out of it, not 1. My test light only measures 6 or more volts...so if it was the right plug I had no way to tell other than start cutting and splicing. *cringe*

The car is a 90' so i'm guessing that might have something to do with it...seems any "how to" I find is for a 91+. I think the wires coming out of that plug are green w/ white, blue w/ white and one other.

Lack of tools < all. (I'm working in my dorm parking lot.)

Any more ideas? =P


--Symple

 

[DSM90AWD]

I can't remember where I found the Instructions but RRE had the "Blue Wire Mod' for the S-AFC which also ties into that plug.

Anyway.. I have a 1990 so went out and shot a pic for youHERE

Can see my lame attempt of an arrow pointing to the correct plug. Can see the one you were talking about in the forground (three wire one).
It may be hidden or taped over so keep looking till you find it

 

[symple]

heh, kickass. I'll go dig (some more) tomorrow. After all this crap, I'm just hoping I don't need a new o2 sensor. I just got my fuel pump today. Not sure I want to do a parking lot install on that.


Thanks again. I'll let yah know what I find.

--Symple

 

[symple]

It's done. Got the gauge working. That pic helped tons. The connector was stuffed so far under there I had a hell of a time reaching it.

My interior can finally be put back together!

Thanks again,
Symple