Help ID engine bay wires please.

[dewme5]

New to me 92. Sorting little issues, and lots of progress so far. The cats and o2's have previously been removed, and this thing runs a bit to rich, so I would like to put the o2's back in.

The #1 O2 wires and connector are present. Wires come out of the room at the driver inner fender, run down outside of the frame rail, clipped in the original location.

#2 is not to be found. I think I remember reading somewhere that those wires snake across the trans. I do not see a connector that is right, or the correct wire colors where I would expect them to be.

The 3fe fsm schematics I have show Ox2 wire colors to be Y-R, W, O, and BR. I have found a stripped out of tape bundle of wires that match most of the colors, so I am hoping someone can look at the location of the loom split, and give a little guidance.

As the harness leaves the firewall, under the wiper motor, the second T which also has the distributor signal wires, is where this bundle I am asking about first becomes visible. There are also some thicker wires both gray, that I also have no idea about that can be seen.

Any ideas?

 

[voodu3]

These may help:

O2 sensor 3fe location

forum.ih8mud.com

Search results for query: 3fe o2 sensor

forum.ih8mud.com

 

[dewme5]

These may help:

O2 sensor 3fe location

forum.ih8mud.com

Search results for query: 3fe o2 sensor

forum.ih8mud.com

That does help confirm that the wires go across the transmission, but not much more than that. Not being super familiar with this engine setup, and getting into the previous owners changes, makes things a little difficult. I have made huge use of the search function already, but I am not finding what that wire set may be.

 

[jonheld]

This harness should be pretty easy to verify with a multimeter if you have the schematic.
Yellow/red stripe should be +12 with key in ON position (from EFI relay)
Brown should be ground.
Orange should run to the ECU connector E4 pin 1.
The oddball is the brown/black stripe. That is shown as a ground from several points on the ECU.
You appear to be missing the solid white, but it's hard to say from the pictures if the solid brown is actually discolored white.
You could check continuity between that wire and pin 11 of the diagnostic connector on the firewall.

 

[dewme5]

Working on things now. Seems the oddball big gray wires were the replacement ones..

For now, I have an innovate wideband setup that outputs a narrow band signal for the ecu. That's going in, and I can ideally keep track of what is going on.

 

[dewme5]

Just to close this out for now. Not sure why the grounded shroud was added to the white wire, but it seems to be original. Some stuff was chopped in the engine bay, so I modified things again to my need by putting in the wideband O2. I have a single O2 on the front bank, which sends directly to my Innovate MTX-L gauge, which in turn has two output signals that i have set to replicate narrow band signals. One signal goes to OX1, the second to OX2. For now, it has made a pretty dramatic difference in performance and smell.

The engine was not full cold on the first fire up after the install. 70 deg ambient, and maybe 120 on the engine. After starting, the O2 heater cycle takes about 30 seconds before a stable idle O2 reading is obtained. At this point, the AFR was steady in the 10.5 range, and dipping into the mid 9's when touching the throttle. Started a test drive, and once the temp gauge was normalized in the middle, AFR's were in the 11's, and still rich on accel or decel. This test drive was a pretty short, maybe 3 miles after full warm. AFR's creeped into the 13's in steady state driving. Then parked overnight.

The following day, about 11am, fully cold start, was the fastest starting event since I have owned the truck. Started smooth, and idled well. Pulled out immediately, and went for another test drive. This time, first afr read is mid 11's while still warming up. Once fully warm, steady state load on all moderate RPM's were mid 13's to mid 14's. Decel down lager hills would peg the gauge at 22.4 AFR. Hard accel would drop into the low 11's. Probably a 5 mile test drive after full warm. Much better throttle response, and smell.

For anyone suggesting that the 3fe is good to go without the o2's, I would completely disagree. Previously, the large hill near my house would require second gear at high rpm to start at 50mph, and end about 42mph. Now, during just the second test drive after replacing the O2's, that same hill I can steady state 50mph, in third gear.

 

[dewme5]

Maybe not as good as hoped. I put in a 500 mile trip, steady state on the highway, and the response was all over on the AFR's. Acceleration, or pulls up long hills would give good results, steady high 13's, but the rest of the time, it wanted to sit somewhere between 10's and 11's. That is the safe rich number for wide open throttle on a race motor with a turbo. Way to much fuel is being thrown away. Everything is running well, the engine is smooth, plugs, wires, injectors are good. No vac leaks detected. I do have a reman ECU, but I do not know if someone modified/chipped it. That will be the next investigation.

Doing 60mph at 11's, hit the throttle, afr's move to high 13's. 13's are good, the 11's are way wrong.
Doing 60 coming down the hill, let off the throttle, moves afr's into the 10's. WHAT???
Doing 70 coming down the hill, let off the throttle, moves afr's to 22.4, which is max lean. This is correct, or could be considered correct.
Idle will start at 11's, and then move to 13's. over about 45 seconds. should be 14.7.
idle, blip the throttle, 11's jump to 13's.

Since I do not have the correct inline resistor to simulate a heater, I do not know if the ECU is actually registering the info as it should. Such as:
No heater = throw code AND ignore signal for the first minute, then use o2 to adjust mixture.
vs
No heater = throw code and ignore any signal.

I'll keep playing a bit, but will probably just put a Haltech on it, and get full control that I would like. With will also make doing a turbo easier as a future upgrade. Nothing crazy, but a few PSI would make enough difference that I could actually not slow down going up a standard grade.