1994 Fj80 Code 26, running rough, and Oxygen sensor wiring (2 Viewers)

Joined
Aug 28, 2014
Messages
5
Location
Half Moon Bay, Ca
Newbie here,

My 94 land cruiser is idling a little rough upon starting. Problem gets much more severe when accelerating. Hesitation and cutting out when attempting to accelerate, when returning back to idle the shake is fairly severe. I have to this point:
*Removed, cleaned and checked the EGR valve
*Checked the intake hose for leaks, all good
*Checked and replace as needed vacuum hoses
*Cleaned the connector on the O2 sensor closest to the outside of the body
Questions:
1) My next step was to do the same with the inside O2 sensor. But I found that the previous owner had replaced this sensor with a Bosch sensor. In doing so they cut off the factory connector and added the Bosch universal connector. I am going to order new O2 sensors x2. My question is what is the best way to handle the inside O2 connector since the original is gone? Splice or is it possible to order a new connector? Where can I find a wiring diagram for either the splice or new connector?
2) After I checked the EGR, intake hose, vacuum hoses, and cleaning 1 O2 connector upon starting it was still running rough. I then pulled the EFI fuse to reset the code and upon restarting the car ran perfectly. Does this make sense? I have little faith this will last and suspect that the issue will re-appear shortly?

Lastly, are NGK O2 sensors OK, or should I stick with Denso or Toyota? And am I on the right track or should I be looking at something else?

Thanks so much,
Mark
 
Joined
Aug 25, 2014
Messages
179
Location
Olympia, WA
Try inquiring at cruiserparts.net im sure there are plenty of others if they dont have any. Also if there is a toyota certified shop near you youd be able to get one from there.
 
Joined
Aug 28, 2014
Messages
5
Location
Half Moon Bay, Ca
Thanks again kuneefay. I got ahold of Beno and he was able to hook me up with the o2 sensors, connector replacement and splice kit. Also order a few other parts while I was at it. Beno is the dude!
 
Joined
Sep 19, 2006
Messages
188
It's a fawking trap I tell you!
Ignorance of how to treat a code that is.


A code is a point where you start diagnostics not always where the problem is. Buying parts before doing diagnostics is often throwing money away.

O2 sensor will not cause a rough idle or any of the problems you are listing, O2 only adjusts fuel mixture when at cruise. If it's bad eventually you might foul plugs.
You getting a O2 code is likely the ECM saying "I am seeing a mixture problem". In this case 26 is rich mixture not likely it's a fault of the O2.
What will cause your symptoms:
Vacuum leaks and always the first thing to look for.
EGR issues in particular the modulator.
EGR is closed at idle and acceleration. If it's not closed at idle or acceleration it will cause exactly your complaint. It opens at steady cruise. A bad modulator is the most likely cause of your complaints. It being plumbed wring (ports flipped around). Even the cheap repair manuals list diagnostics on the modulator. A bad VSS valve can also cause this complaint as it kills vac to the EGR on command from the ECM. It's probably ok since it would be closed at cold start and open once engine gets to operating temp. In line with your symptoms of gets worse as warms up.

Put a vac gage on the hose going to the EGR valve and see when it opens. No vac gage then just plug the hose and see how it drives. Should drive fine but eventually throw another code at steady cruise as it goes overly lean from the EGR not opening.

Other possibilities

Bad plug wires
Bad cap and button
Bad plugs
Bad coil.
Clogged cat. The EGR modulator also has a hose from exhaust and excessive back pressure will cause it to function incorrectly.
 
Last edited:

arcteryx

Supporting Vendor
Joined
Sep 27, 2004
Messages
7,733
Location
Austin
I just went through this last month. I put on new 02 sensors, it didnt help. I finally called uncle and put it in a local shop that specializes in Yota/Lexus. Turns out, my #6 injector was bad which was caused by a coolant leak. The inside of the injector pins were were pretty much gone, so I was running 5 basically. Tremendous shaking, rough idle, and it threw a knock sensor code too. I mentioned this to Tucker and he said his #6 went out too. Hopefully this isnt it. If it is though, get the rest of your injectors cleaned, I did since it was all off.
 
Joined
Jul 10, 2015
Messages
10
Location
Florida
Newbie here,

My 94 land cruiser is idling a little rough upon starting. Problem gets much more severe when accelerating. Hesitation and cutting out when attempting to accelerate, when returning back to idle the shake is fairly severe. I have to this point:
*Removed, cleaned and checked the EGR valve
*Checked the intake hose for leaks, all good
*Checked and replace as needed vacuum hoses
*Cleaned the connector on the O2 sensor closest to the outside of the body
Questions:
1) My next step was to do the same with the inside O2 sensor. But I found that the previous owner had replaced this sensor with a Bosch sensor. In doing so they cut off the factory connector and added the Bosch universal connector. I am going to order new O2 sensors x2. My question is what is the best way to handle the inside O2 connector since the original is gone? Splice or is it possible to order a new connector? Where can I find a wiring diagram for either the splice or new connector?
2) After I checked the EGR, intake hose, vacuum hoses, and cleaning 1 O2 connector upon starting it was still running rough. I then pulled the EFI fuse to reset the code and upon restarting the car ran perfectly. Does this make sense? I have little faith this will last and suspect that the issue will re-appear shortly?

Lastly, are NGK O2 sensors OK, or should I stick with Denso or Toyota? And am I on the right track or should I be looking at something else?

Thanks so much,
Mark
Did you ever resolve this?
 
Joined
Feb 1, 2017
Messages
4
Location
Austin, TX
Did you ever resolve this issue? I'm experiencing something very similar with my 1997 LC.

Mine threw the check engine light (turns out O2 sensor, bank 1 sensor 1) recently on a road trip and then it began missing. The missing is very sporadic and now it's gotten to the point where it misses so frequently, it doesn't feel safe to drive. My local LC shop in Austin is overbooked, so they can't look at it until next week. They suggested replacing plugs...I did and the truck ran great for all of a mile, and now it's back to sporadic missing.

Was your problem due to a bad injector? After reading the forums exhaustively, I have read about similar symptoms that were caused by:
1) failed capacitors on ECU (I don't know where the ECU is located on this truck but might be something worth me checking)
2) bad injector(s)
3) defective throttle position sensor
4) bad gas (I've ran through two tanks of fuel now and put water treatment as well as fuel system cleaner through it)
5) bad spark plugs - I already replaced these

Thoughts?

Thanks in advance for any input you guys can provide. I was hoping to use this truck to pull a small U-Haul trailer of furniture to a new home I purchased this weekend, and now it's looking like I might have to cancel plans since the truck isn't running reliably.

-Joe (New LC owner and future forum contributor in Austin, TX)
 

ppc

M Go Blue
Joined
Aug 18, 2003
Messages
3,285
Location
Nashville, TN
Check the wiring harness that runs next to the EGR. There are many threads that describe this and show pictures. It may look intact but needs to be opened up and individual wires checked.
 
Joined
Sep 14, 2015
Messages
8
Location
Upland Ca
Newbie here,

My 94 land cruiser is idling a little rough upon starting. Problem gets much more severe when accelerating. Hesitation and cutting out when attempting to accelerate, when returning back to idle the shake is fairly severe. I have to this point:
*Removed, cleaned and checked the EGR valve
*Checked the intake hose for leaks, all good
*Checked and replace as needed vacuum hoses
*Cleaned the connector on the O2 sensor closest to the outside of the body
Questions:
1) My next step was to do the same with the inside O2 sensor. But I found that the previous owner had replaced this sensor with a Bosch sensor. In doing so they cut off the factory connector and added the Bosch universal connector. I am going to order new O2 sensors x2. My question is what is the best way to handle the inside O2 connector since the original is gone? Splice or is it possible to order a new connector? Where can I find a wiring diagram for either the splice or new connector?
2) After I checked the EGR, intake hose, vacuum hoses, and cleaning 1 O2 connector upon starting it was still running rough. I then pulled the EFI fuse to reset the code and upon restarting the car ran perfectly. Does this make sense? I have little faith this will last and suspect that the issue will re-appear shortly?

Lastly, are NGK O2 sensors OK, or should I stick with Denso or Toyota? And am I on the right track or should I be looking at something else?

Thanks so much,
Mark
Also check the Mass Air Flow Meter. I had similar issues. There is a you tube video on Mass Air Flow Meters 1994 landcruiser. I found a dead spot on the electrical and had to send it out to be rebuilt. I couln't find a new one. Good Luck
 
Joined
Aug 3, 2020
Messages
25
Location
California
yeticruiser, which O2 sensors did you install? Toyota, Denso or something else? I cannot find any Toyota sensors because they have been discontinued. I tried NTK and seems to generate incompatible signal. I'd appreciate it if you could give me some information.
 

ppc

M Go Blue
Joined
Aug 18, 2003
Messages
3,285
Location
Nashville, TN
The OEM sensors for the 94 were NTK brand. What specifically do you mean by "generate incompatible signal".
 
Joined
Aug 3, 2020
Messages
25
Location
California
When I installed second NTK on bank 2, my LC started to drive very slow like missing a couple of cylinders although still smooth. I thought I got a incompatible NTK. Is the NTK 24044 correct model? My LC runs better with the wire disconnected, so I figured the sensor is sending wrong signal/voltage.
 
Joined
Jun 19, 2018
Messages
638
Location
Seattle, Wa USA
It looks like the simplest potential cause of those codes is a loose engine ground bolt. It gets steadily more complicated from there.
 

Users who are viewing this thread

Top Bottom