Replaced O2's to clear code 26, now I'm getting 25 with no symptoms? (1 Viewer)

Joined
Jun 14, 2018
Messages
6
Location
San Diego
Hello everybody,
My name is Chris and I have a 1993 FZJ80, 255k on the clock, purchased 2 years ago at 225k. The truck has a long history of being neglected, and I have been putting it back together for the last couple years.

Recently, the idle started to s*** itself. Under load things would be fine, but in park or just idling the truck felt like it was shaking. After about a month, it became a consistent code 26(rich) along with symptoms. At this time, I also started to lose power and the truck began hesitating.

Fast forward to today, I had tried a couple things to fix it, and the only one that worked was replacing the original??? toyota O2 sensors. Very strange to find something that is not chinese on this truck. So I think they may have been original. The only thing that helped the idle while I was waiting for the sensors was unplugging them. It seemed to go back to normal(What the truck has always felt like).

I also... wrapped the harness at the EGR(was beginning to melt a wire), checked grounds/vacuum hoses and whatnot. Everything looks good.

I sourced some of the NTK O2 sensors, removed the old ones and installed while cleaning out the the plugs(historically every tie it rained it would f*** up the outer sensor, I now wrap it and grease it).

Pulled the EFI fuse and for the first time ever, the car did not begin by pushing the RPM's up to 2k. The truck has always smelled like a gas station, burned fuel or oil(not sure) and was running rich.
After the first test drive, code has vanished and was much more peppy, no hesitation, and no s*** idle. I was very happy.

2 days later, everything still feels fine, but the truck is throwing a code 25, lean. I know that a lean condition is not good for your engine, and has me concerned.

As far as truck history, it was a cartel truck(found a loaded gun in the bumper and got it in San ysidro San Diego) and I have touched almost every system. Not that everything has been replaced, but something has been adjusted or touched from pretty much all systems, so I just don't want to list everything.

I keep reading about PAIR valves and whatever the (not a MAF) is called. Originally, I thought I was having a fueling issue until I found out he O2's were shorting and replaced em.

Thanks guys.
 
Joined
Jun 14, 2018
Messages
6
Location
San Diego
Oh yeah one more thing.... Could I have been lean the whole time, but running rich because of the O2 sensors? This is the current hypothesis.
 
Joined
Jun 14, 2018
Messages
6
Location
San Diego
Update: She's running much better, but still throwing intermittent code 25. Idle sitting just above 600 and it seems like there's a slight misfire but no shaking like before. Light is on about half the time I'm driving, usually on while I'm sitting at a light or cruising around town. Haven't seen it come on while on the freeway yet. Seems to be better under load, but lean while idling/coasting?

Also fixed the 8 pin barrel plug and cleaned and switched the contacts in the NSS. All lights now working and it never starts in 2nd anymore!
 
Joined
Jan 27, 2015
Messages
177
Location
North Carolina
I was having very similar issues and it turned out the #6 injector was bad. It started out with occasional 25 code and mild stumble/misfire occasionally. gradually it got worse and i was able to determine what the issue was.
 
Joined
Jun 14, 2018
Messages
6
Location
San Diego
Hey everyone,
Still dealing with an intermittent lean CEL.

Updates:
1.Pulled fuel sender/pump assay, looked like a shipwreck, I have never seen so much rust. Tried to clean it best I could, and got the float moving again(never had a gauge before). I then replaced the sock filter and reinserted the unit. Started the truck up, everything seems the same.
NOTE: PO had crimped(im not sure what these are called but its like a little plastic clamp with a metal tooth that "bites" into your wires) one of the pump wires?.... No idea why.
Everything was good over the weekend, no issues, but still had my lean light.

Since replacing the fuel sock and fixing the bobber, I now have a gauge! Strangely, it seems the low level light(which had always worked) stopped working?

2.Went to go to lunch earlier today, car cranked and started as normal, and then died after about 5 seconds. It sounded and felt like I ran out of gas. I was watching my new gauge, which never hit 0, and my low light never came on. Next I went down to the store, filled up my gas tank, and walked it back to the truck. After 2 trips, 6 gallons, I convinced myself that no amount of gas would fix whatever was the issue.

3.Pulled the fuel sender again to make sure something hadn't gone wrong when I was messing with it, but all seems normal. Reinserted the fuel sender.

4.Replaced the fuel filter, after messing around with my very rusty sending unit, I was worried that the rust had traveled up into my filter and clogged it. When I replaced it, a little bit of orange gas came out initially, but the rest was clear and clean.

Car cranks well, sounds like it has spark, but wont turn over. It had started 1 time, after leaving the ignition in the "electronics on" position. I turned the car off after about a minute, and we are back to square one, it will not turn over.

littlegreenmonster mentioned he had similar symptoms when injectors were going out. Other than checking injectors and doing general fuel pressure readings, I do not know where else to troubleshoot.

@littlegreenmonster when it got "worse", what were the symptoms?

Thanks guys,
Chris
 
Joined
Jan 27, 2015
Messages
177
Location
North Carolina
Hey everyone,
Still dealing with an intermittent lean CEL.

Updates:
1.Pulled fuel sender/pump assay, looked like a shipwreck, I have never seen so much rust. Tried to clean it best I could, and got the float moving again(never had a gauge before). I then replaced the sock filter and reinserted the unit. Started the truck up, everything seems the same.
NOTE: PO had crimped(im not sure what these are called but its like a little plastic clamp with a metal tooth that "bites" into your wires) one of the pump wires?.... No idea why.
Everything was good over the weekend, no issues, but still had my lean light.

Since replacing the fuel sock and fixing the bobber, I now have a gauge! Strangely, it seems the low level light(which had always worked) stopped working?

2.Went to go to lunch earlier today, car cranked and started as normal, and then died after about 5 seconds. It sounded and felt like I ran out of gas. I was watching my new gauge, which never hit 0, and my low light never came on. Next I went down to the store, filled up my gas tank, and walked it back to the truck. After 2 trips, 6 gallons, I convinced myself that no amount of gas would fix whatever was the issue.

3.Pulled the fuel sender again to make sure something hadn't gone wrong when I was messing with it, but all seems normal. Reinserted the fuel sender.

4.Replaced the fuel filter, after messing around with my very rusty sending unit, I was worried that the rust had traveled up into my filter and clogged it. When I replaced it, a little bit of orange gas came out initially, but the rest was clear and clean.

Car cranks well, sounds like it has spark, but wont turn over. It had started 1 time, after leaving the ignition in the "electronics on" position. I turned the car off after about a minute, and we are back to square one, it will not turn over.

littlegreenmonster mentioned he had similar symptoms when injectors were going out. Other than checking injectors and doing general fuel pressure readings, I do not know where else to troubleshoot.

@littlegreenmonster when it got "worse", what were the symptoms?

Thanks guys,
Chris
It started misfiring enough it could be narrowed down to cylinder #6. It had spark, so next culprit was a fuel delivery issue.
 
Joined
Jun 14, 2018
Messages
6
Location
San Diego
The new pump is in, and the truck started right up. Still getting my lean code, but starts perfectly and idles perfectly, no more lack of gas!

Still cannot figure out why it throws the intermittent lean code, anyone know of a good way to check injectors? I was under the impression I will have to at least take the intake manifold off to get to them.

Thanks!
 

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