Hello, new amigos! First post and first question! (1 Viewer)

[TN FJ 80 Guy]

Good evening fine folks at Ih8mud! I'm new to the offroad and LC scene, after being introduced to the joys of offroading last summer.

I knew this hobby was my next one.

Fast forward 8 months and I'm the proud new owner of a 1991 beige/cedarwood FJ80. 270k miles and a bit of rust, but she is a beauty. I hit the ground running with undercarraige rust treatment/prevention. I'm in the process of making her offroad safe: I've added a slee short bus bumper, and I have Cruisin Offroad skids, sliders and OME 2.5" lift awaiting install. Trying to find time between my other hobby (see my avatar)

I have been getting acquainted with this site for the past few weeks and I can tell that this is a group of passionate and knowledgeable folks who are ready to help!

That being said...

I have run into something that I haven't found yet on the forum. The PO (new to forums so still geeking out on the use of acronyms) completely bypassed the o2 sensors. Literally, one is sitting on top of the pipe forward of the catalytic converters, and the other is just missing. He welded straight pipe through this area. However, I have no CEL, and no problems with the engine running or starting. I'm concerned about gas mileage, surprise! But also questioning how my rig runs well without the input from the o2. I have checked all fuses in the cabin and under the hood and everything checks out. CEL does not illuminate on the ON posiston either. I'm wondering if the circuit is bad or something else is going on with that, but that still doesn't answer the question of why no functional indication of missing sensors. I'm hoping that someone can point me in the right direction.

Thanks again, and I look forward to meeting some of you on the trails in East TN. I'm in Maryville and will spend quite a bit of time at Windrock.

All the best,
Tony

 

[Corbet]

Welcome.

I can't help much on the O2 sensor questions. I'm more familiar with my later FZJ

 

[EngEngr]

welcome.

could just be a bulb burned out or the PO took it out so that the CEL wouldn't be lit up all the time and that it would sell? My door ajar bulb was burned out when I dug into mine to add diff lock bulbs. Without input from the O2 it will probably be running in open loop fueling

 

[Chicken Hawk]

Hook a scanner up to it for codes stored.

 

[SeaWheezl]

If the CEL doesn't come on when you turn the key on before starting, very likely the bulb has either been removed or burned out.

 

[LS1FJ40]

I'm thinking that the O2 sensors on the 91-92 don't communicate with the ECU and thus the CEL the same as later years. When I replaced mine one was hanging out completely. No code. Have no idea how long the bolts had been rusted/broken off.

@jonheld can you clarify this. Am I completely off base.

Oh, and welcome to Mud. People will say that Land Cruisers are an expensive hobby but not nearly as expensive as the hobby in your avatar.

 

[Maleficio]

My old '82 Porsche 928 had a 1/4" plug for the O2 sensor. When I unplugged it the car ran stronger.

 

[panamacruiser]

O2 sensors are for fuel injected vehicles, yours is a 91 so no OBD2 scan for that one...what engine do you have on it? I don't think is a fuel injected (thus needing a computer a MAF an O2 etc etc etc)
Also...mine is a 1HD-T so not much familiar with a gasoline engine in a LC, but on my other car yes...I said car, no truck...

 

[TN FJ 80 Guy]

Hook a scanner up to it for codes stored.

I tried to look at the code to no avail. I can't get the light to turn on at all. I suppose I will be getting into the dash to get this thing figured out..Unless there are OBD I readers similar to OBD II? I'm not familiar with the system.

 

[TN FJ 80 Guy]

Thank you everyone for the immediate welcome and support, by the way! Very cool to be a part of the group!

 

[TN FJ 80 Guy]

O2 sensors are for fuel injected vehicles, yours is a 91 so no OBD2 scan for that one...what engine do you have on it? I don't think is a fuel injected (thus needing a computer a MAF an O2 etc etc etc)
Also...mine is a 1HD-T so not much familiar with a gasoline engine in a LC, but on my other car yes...I said car, no truck...

I have the 3F-E, so it has the EFI system with the older OBD I system...

Man I would love to have a diesel in a LC! Armageddon proof!

 

[Malleus]

The early Toyota OBDI systems don't supply very much information. Your best bet is to get the Toyota Factory Service Manual. You can download it here:
https://techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&contextType=external&username=string&password=sercure_string&challenge_url=https://techinfo.toyota.com/techInfoPortal/login/techinfo&request_id=-8269842152579381113&authn_try_count=0&locale=en_US&resource_url=https%3A%2F%2Ftechinfo.toyota.com%2Ft3Portal%2Fappmanager%2Ft3%2Fti%3F_nfpb%3Dtrue%26_pageLabel%3Dlib_repair_sum
You'll only need a two day subscription. The fee is $15. Best investment you can make for your truck.

 

[mct75]

I know mine throws a code when the O2 sensors are unplugged, but it runs fine without them. I think the 3FE EFI system is too stupid to die.

 

[EngEngr]

I know mine throws a code when the O2 sensors are unplugged, but it runs fine without them. I think the 3FE EFI system is too stupid to die.

O2 senors are just binary fuel trims based on rich or lean measurements. If you have a code or a bad o2, the fuel system will usually default to open loop fueling tables. It will run, just won't be optimal. Remember they are sensors driven by emissions requirements

 

[TN FJ 80 Guy]

I know mine throws a code when the O2 sensors are unplugged, but it runs fine without them. I think the 3FE EFI system is too stupid to die.

This comment made me chuckle...

 

[jonheld]

I'm thinking that the O2 sensors on the 91-92 don't communicate with the ECU and thus the CEL the same as later years. When I replaced mine one was hanging out completely. No code. Have no idea how long the bolts had been rusted/broken off.

@jonheld can you clarify this. Am I completely off base.

The O2 sensors are the primary feedback for the ECU in regards to fuel trim. There are ways of "fooling" the ECU with fixed resistors, but that's not something I would ever want to do. In this case, the ECU will have no way to know if you are rich/lean and it will make adjustments based on false readings from the O2 input, valid readings from the AFM, TPS, and coolant temp. In certain conditions you will be running way too rich.

I am not certain what will trigger the CEL error with the O2s. Mine were very old and WAY out of spec when checked according to the FSM and I got a code that cleared right away. When I had a fractured wire, the error was constant.

 

[2 E L O]

Welcome! Looks like a great truck!

I can't contribute anything to your issue, but good luck getting it worked out!

 

[pengfinn]

Nice truck, almost identical to mine! Welcome to mud!

 

[jdayment]

Since the CEL does not illuminate in the on Position I would start with checking to see if the bulb is there or burned out. The CEL is handy on the 3FE for when the EFI relay stops working.

 

[jonheld]

Hook a scanner up to it for codes stored.

Not on an OBD1 vehicle. You will need to short terminals 3-6 on the check connector on the firewall and decipher the blinking CEL lamp which will display the stored 2 digit codes.
This assumes the CEL lamp is working.