My "new" FZJ80 - CEL woes already...

[TX FJ80]

269K, no drips, leaks, etc. Run strong and sound great except for a little exhaust tick, sounds like coming from donut gasket.

So I bought this 1994 truck as a daily. I work from home and just need something that starts every time and I can beat on a little. Coming from the W123 Mercedes world, where every week something is leaking, broken, etc., I figured Toyota was a little safer bet.

Last night, the truck started up and was SO RICH it was burning my nostrils it seemed. It smelled like raw fuel coming out of the exhaust. BUT, it simmered down and there was no CEL, so I picked up lady from the airport. While waiting, the CEL came on and the smell returned along with erratic idle (every few seconds - up, then down, then up, then down). But then went away. Did not have a choice really, so drove us home and this morning I followed instructions on here (thanks, fellas!) and pulled my CEL codes. Let's just say I am non-plussed at what I read.

CEL is currently off and raw fuel smell is not present.

1 - Normal
2 - Air Flow meter signal
25 - Lean mixture
26 - Rich mixture

From what I have read about these codes, could I be looking at PAIR valve (what is that, anyhow?)? Am I being dense that it shouldn't be O2 sensors, since neither of these codes (27, 28) is set? Just am trying to get my bearings straight before embarking here. I am skilled with a wrench, multimeter, etc., so not scared of heavy diagnostics.

I am not a parts hanger guy. I am looking for a systematic way of diagnosing and replacing the offending part. Also, I am not looking to dump significant $$ into my beater.

Any advice?

 

[OGBeno]

The FSM has a systematic way of diagnosing and figuring out the offending part(s).

Review the FSM and you will solve your problems.

 

[DSRTRDR]

FSM can be found here: https://forum.ih8mud.com/threads/40-50-60-and-80-series-fsm-for-a-hell-of-a-price.610994/

 

[TX FJ80]

Sweet. Thanks guys.

Quick question - I downloaded the 1994 FZJ80 FSM and unzipped it. Where in the directory structure would I find the troubleshooting section?

The maintenance section is referencing the 22R and 3VZ engines - not what I expected?

Halp? Sorry in advance for being obtuse.

 

[TX FJ80]

I have clicked through these PDF for 30-40 minutes and I cannot find a step-by-step guide from CEL code to 1 through X steps to diagnose.

 

[OGBeno]

It will be in the EFI section under DTC.

 

[TX FJ80]

It will be in the EFI section under DTC.

Thanks! Found exactly what I was looking for.

 

[TX FJ80]

Followed procedure on pg. "EG-227", which is the DTC Detection Driving Pattern for the DTC 25,26 situation I am experiencing.

Nothing. So I did it again. Nothing. Are the procedures coming upon with no help because I am only experiencing the CEL intermittently?

 

[TX FJ80]

Climbed underneath it this afternoon when the sun was out and the temps were up - any special trick to getting the O2 sensors to unplug to test the resistance?

I had a flat blade under the tab and was pulling to the point I thought I might just break something. Trying to exercise and abundance of caution - again - I'm from the Euro world and would rather ask and look silly than go i

 

[TX FJ80]

sorry - that got cut off - it should have ended with:

"rather than ask and look silly than go in all ham-fisted and start breaking things, causing more problems!

 

[TX FJ80]

So, out of town for work, but still reading the FSM...

Still trying to figure out if there is a way you have to hold your mouth right to get the dang connector loose...

Also, where does the driver's side O2 bank wiring eventually route once it heads up and over the transmission bellhousing?

I saw on another thread RE: DTC25/26 where this wiring had a bad ground and caused intermittent issues similar to mine. I have been reading the FSM wiring but the schematics just tell you routing of the wiring, not necessarily physical locations of all the ground points. Probably not a bad place to start on a 20 year old rig.

Pics attached of the wiring.

 

[wchain]

How about the intake tube? Is it cracked?

Did you used to hang out at peachparts?

 

[TX FJ80]

I have inspected it visually twice - but I am going to take it off and devise some better way to test it. It looks newer than 20 years old, though. Maybe time to do a "carb cleaner" test around it with it running?!?

I was active on BenzWorld, Turbobricks, and Swedespeed. Only lurked on peachparts.

The inside of my garage houses two W123 diesels.

 

[Bimmerista]

Buddy of mine down in Austin is a big time Malaise-era Merc diesel guy. He'd appreciate what you have in the garage.

I'm more of a BMW guy, but one thing I preach to those that don't understand our appreciation for these OG German cars, is that they're built to last FOREVER. Just like Land Cruisers.

P.S. - What part of DFW are you located? I'm near Lake Lewisville.

 

[TX FJ80]

I am over by White Rock Lake in East Dallas.

So, update as to where I am on this CEL issue. As folks have suggested here, I checked my air intake hose today - took it off and visually inspected it - flexing it around the accordion part and looked for hairline cracks, etc. Everything looked great. Tightened up and checked every single ground I could find, cleaned up my battery terminals too as they looked corroded and ratty.

CEL came on for 30 seconds driving back from Pep Boys where I bought some bulbs.

I sure hate to hang parts on it and the FSM procedures have yielded 0 positive test results for bad O2 sensors. ECT seems like a promising lead, but boy is it a PITA to get to. I'm used to my old Germans - literally able to see and touch every single part on the car and almost nothing has to get removed to get to another part. Have a slight curve getting used to this engine bay.

 

[Mikeb1]

I had similar symptoms with my 93. Ended up being the EFI relay was bad. The EFI relay is in the engine bay, driver side in the fuse box. Drive your truck around until warm, then check to see if the relay is hot. I could barely touch mine it was so hot. Good luck.

 

[TX FJ80]

I had similar symptoms with my 93. Ended up being the EFI relay was bad. The EFI relay is in the engine bay, driver side in the fuse box. Drive your truck around until warm, then check to see if the relay is hot. I could barely touch mine it was so hot. Good luck.

Thanks for the tip! So, you are telling me your EFI relay was failing but you didn't have hard starting, just intermittent engine light and rough running? Everything I have read about the EFI relay is it just causes a no start condition.

Thanks again!

 

[TX FJ80]

This little fella was VERY hot to the touch after running for only 5-10 minutes. Ruh-roh.

Anyone want to weigh in?

What's drawing more juice than it should?

 

[TX FJ80]

Anyone want to weigh in on how this little relay could cause intermittent DTC 25/26? Want to do as much research as possible before hanging parts.

 

[CoffeeGeek]

I have inspected it visually twice - but I am going to take it off and devise some better way to test it. It looks newer than 20 years old, though. Maybe time to do a "carb cleaner" test around it with it running?!?

I was active on BenzWorld, Turbobricks, and Swedespeed. Only lurked on peachparts.

The inside of my garage houses two W123 diesels.

I had a 240d. This is one of a the few vehicles on the road that a lifted big tire armored 80 series can beat 0 to 60mph. Although that old mercedies would cruise down the interstate like nobodies business with the spedo buried and the diesel clackity clacking away. Good times lol