Aaron's 1991 land cruiser 270k (1 Viewer)

[Ace4]

I'll check tonight for a ballast somewhere. I remember seeing one, but for some reason I thought it was for the led accessory lights. Well, the harness does work, so I might try to replace the bulbs for something less green and keep the new bulbs as a back up.

 

[Ace4]

I had the old 02 flange cut out and the new one welded back on. I also had him replace the o2 sensor while he had it up. The muffler shop charged me $40 which was totally worth it for me. I pulled the EFI fuse for ~10 mins, but the CEL 28 remained on. The fuse is currently out as it's sitting in the drive way, but I think 10mins should have been plenty of time. The FSM exhaust diagram has me thinking the o2 sensor closest to the drivers frame is actually is the #1 o2 sensor, and the one closest to the transmission is the #2. I think I had this backwards in my previous post.

I guess it's time to find the voltmeter, and start testing. My best guess is a shorted / cut wire somewhere on the harness.

 

[Ace4]

Alright, so I'm not getting any voltage to the OBD module for the #2 o2 sensor. I crawled under to take a look. The wire harness to the o2 sensor is greasy, wet and and had splices all throughout. I couldn't quite figured out where the harness went, but I think it goes up over the transmission and the straight up to the cab of the passenger side. If I can figure out which harness is the #2 o2 sensor from in engine bay I could fish it out and check the continuity. It might be better to just buy a harness if I can find one. I'm not sure how I'd get it back.

I also noticed that there was one harness unplugged with nothing to go to it on in the passenger side. In picture 2 there is what looks like a grounding connection for a bolt that is just hanging there. This is between the transmission and the center diff.

The FSM doesn't seem to be very helpful for determining how the wiring is run.

I ran out of light and didn't have time to take it to the shop so that's all the further I got tonight.

View attachment 2177023

 

[Ace4]

Ok, I still can't get the CEL 28 code to clear.
I inspected my new o2 sensors and they are both giving me 6ohms resistance cold. So I ran the FSM oxygen sensor inspection test. I get zero fluctuations then I pull the code 28. VF1 and E1 typically give me ~2.5V (One time I got 5volts which puts me on the over lean track)
VF2 and E1 give me a consistent .03V. is this considered 0 volts? The next step is to disconnected the PCV hose and test over under 0volts. I pulled the PCV hose and it did not effect VF2, still .03V. VF1 spiked up to 5V for a bit then dropped back down to 2.5 . One option is "repair (over rich)" the other option is replace o2 sensor.

At this point I gave up and took the cruiser to a shop. I was charged $100 and told that my bank 2 oxygen sensor (he said the sensor closest to the frame? I still can't find in the FSM or online a straight answer on which sensor is 1 or 2) was bad. He said the harness was tested for continuity and is ok. I was skeptical and asked what it meant that the o2 sensor was bad and he told me it was shorted out. Ok, I just ordered it I can get it replaced. Today the replacement came and I put it in, pulled the EFI fuse and crossed my fingers.
10 mins later the code 28 was still present. I ran the FSM procedure again and ended up at repair over rich or replace o2 sensor depending on if .03v is considered 0V or not.

I figured whatever I'm going to run into DEQ because it's open today and see if I pass. I did not.
I came in at 3ppm for CO when it needs to be 1ppm.

I'm a little at a loss on how to clear the CEL 28. The manual doesn't go much into what "repair over rich" involves, and most of what I find online says replace the o2 sensors. I've done that now twice, but I still can't get CEL 28 to clear and am running rich.

So back to the oxygen sensor test.
Does VF1 correlate to the oxygen sensor 1, and 2.5V is the appropriate voltage to have during the test and VF2 with it's .03V is the problem? I'm back to considering there being a break in my harness because the sensors pass the resistance test.

 

[Roastchestnuts]

love your 91! I am in the 1991 land cruiser club. I would adjust your valves at some point if they have not been done. Mine runs sooo much better after I did it. and I think I gained a few mpgs I have been though the o2 sensor issue. mine were welded in by some moron. When I first got the cruiser one of the bungs leaked exhaust because of a s*** s*** weld. I ended up replacing the whole down pipe with the catalytic converter. now I am throwing a code because the other o2 sensor is bad..... I think this time I might get a muffler shop to cut out and weld in a new bung. how did yours go? here is a pic of mine.

 

[Wyatt Pine]

I would still suspect issues with the harness unless you have confirmed continuity as well. The shop seemed to be wrong with the diagnosis with the O2 sensor so I wouldn't necessarily trust their confirmation of continuity of the harness.

 

[Ace4]

Valve adjustment is definitely on the list. I'm just starting with the o2 sensors first to try to pass DEQ. I don't see a reason to move on to other issues until I can get the code to clear.
The sensor mount went great. I picked up this kit: Toyota O2 Sensor Mounting Flange Kit for Toyota 02 sensors - KIT-1098
The exhaust shop I used was quick and only charged $50 to cut out and weld in the new mount. Call around to get a quote and avoid the exhaust chains as they usually have a set minimum price. Or you could just replace the whole pipe and cat with these direct fits that Jon Held recommends. 6 Cylinder 1991 TOYOTA Catalytic Converters

Wyatt, I think you're right about the harness. At this point it couldn't be anything else. I have spec resistance and the sensor outputs the correct voltage at temp so that just leaves the wiring between the sensor and the diagnosis module. I'm tempted to call the shop and see if they will rediagnos since their original assessment was clearly incorrect, but then what's the point of they couldn't figure it out the first time.

 

[White Stripe]

I think their is a app so you can watch live data for the ecu. Might help with diag

 

[Wyatt Pine]

I don’t know it’s any of those apps for OBD1 trucks

 

[Ace4]

The code is gone! The shop took it back and had another look at the harness. They found a break / short. Their original continuity tests passed, but there wasn't enough wire left to allow the full voltage to pass through. They found and patched the harness. Got it back today, hoping to pass DEQ Friday then move into the rear axle seals and brakes.

 

[Ace4]

Passed DEQ. My C0 dropped from 3ppm to .13ppm. I drove for less than 1/4 tank after getting the o2 sensor replaced and working before I needed to fill up. I was up to 12mpg from 9mpg when the o2 sensors were failing. Not too bad, but I should be much better on this next tank of fuel. I'm hoping for ~15mpg.

 

[Marco Lau]

Passed DEQ. My C0 dropped from 3ppm to .13ppm. I drove for less than 1/4 tank after getting the o2 sensor replaced and working before I needed to fill up. I was up to 12mpg from 9mpg when the o2 sensors were failing. Not too bad, but I should be much better on this next tank of fuel. I'm hoping for ~15mpg.

these rigs are 11/13 in stock trims, combined 12 mph....i doubt you will see 15

 

[Ace4]

I picked up a parts rig. 1993 Fzj80 with a hydro locked blown head gasket. Leather interior and most importantly stock lockers front and rear! I'm going to swap out the axles, take what I want and part the rest out. It has a clean title. It is pretty rare to find a stock locked cruiser anymore so I feel a little bad about parting it out. But it's been in a bender in the front and is very dirty. The previous owner clearly didn't know what they had.

 

[Ace4]

Spent the day pulling the axles on the 93 to swap into the 91. I pulled the e brake all the way to the handle. And I pulled the harnesses to the first junction I could find. So the rear harness went up and back to the left bumper where it went to a connector. And the front harness went up close to the diagnosis box. I know I will need the harness, the switch that connects to the dash, and the bulbs, but I think I also need the floor harness that connects from the back up to the switch. I've heard it's easier to just wire up the rear with new wired then worry about the floor harness. Anything else I'm missing?

It looks like the 93 has ABS brakes. I'm not sure if there is a way to incorporate that into the 91, but I'm not too concerned about it.

Now I just need to decide if I'm going to rebuild the knuckles and brakes while the axle is free or of I'm going to mount it up and do it on the 91. I ordered the axle rebuild from Cruiser Outfitters. And k1155 power stop brake pads and rotors from 4wheel parts.

 

[LandLocked93]

View attachment 2198867

This is the saddest pic I've ever seen.
Take it away!

 

[Ace4]

This is the saddest pic I've ever seen.
Take it away!

It's destined for the bone yard unless I can find a buyer for it with my unlocked 91 axles.

 

[Ace4]

I finished refreshing the front and rear axles. New bearings, seals, gaskets, rotors, brake pads. I didn't go into the differential at all. I also got hub studs for all four corners, but I didn't end up using them.

The rear axle has been installed. Hoping to get the front axle finished next weekend. Then I need to figure out how to wire the lockers up. I still have the donor vehicle and need to pull the switch and ecu. I haven't decided if I'm going to replace the floor harness or just patch them in.

 

[White Stripe]

Your also going to need a disc master and lspv.

 

[Ace4]

Your also going to need a disc master and lspv.

How is the LSVP different from the stock 91? Can I just use the 93? Same for the master cylinder

 

[White Stripe]

How is the LSVP different from the stock 91? Can I just use the 93? Same for the master cylinder

I believe they are different part numbers. So Im guessing they are rated for a different proportioning ratio. I probably wouldn't reuse a lspv from the 93 just because its probably original and no good or borderline no good. Master should work fine if you swap in the 93. I got a new lspv off of amazon for 75 bucks. I also installed a new lspv arm rebuild kit while at it. Proper lspv bleeding and adjustment is critical for proper braking. I adjust my lspv on a icy parking lot so that the front and rear lock up at the same time.