1995 FZJ80 not running smooth / minor sputtering?

[MOcruisin]

correct! mine also had this.. changed the exhaust pipe and installed one with the factory o2 mount and put a new OEM Denso o2 sensor in it. I'm in Australia, so have the same configuration as you. Changing the o2 sensor with a brand new genuine Denso one made a big difference. I also had issues with the plug on the loom side for the o2 which was causing intermittent connections. If I were you, this is where I would start. Btw, at no stage did I ever get a code or engine light for the oxygen sensor, but it was still an issue and not working correctly.

View attachment 4113345

re the VAF, sounds like you have the MAF style, not the old flapper, so ignore my comments re: screw. Could still have issues with your MAF too, but I'd start at the o2 sensor first. They don't tend to love aftermarket sensors and they are an item that need replacing periodically, not often, but don't last forever before they start to transmit unreliable data to the ecu.

I've replaced the O2 sensor with a new OEM part straight from Toyota, and fixed an exhaust leak between the manifold and y-pipe thing. Sadly, to no avail. The battery was unhooked for over 24 hours while I did the job in two sittings and drove my 40 to work, but the sputtering idle still persists. The new sensor definitely looks much nicer, but I am stumped that I can't really tell a difference in the running condition. I'm running out of things to chase, what next? Surely I'd have other symptoms if I was looking at a blown HG or other mechanical damage, right?

 

[Malleus]

Soot is the result of unburnt gas, but you never said what gas you're using, and that will have an effect.

As to the sputtering problem, which I think was the reason for your post, have you inspected the wiring harness leads to the injectors? You can verify the circuits for each injector by connector the injector end of the harness to the ECM end using a DMM. If everything else has been eliminated, this is probably the root cause.

You'll have to remove (at least) the upper intake manifold, and I'd recommend buying (6) of the connector housings, because you will break the latch on at least one, and they will not work with a broken latch. The part number is 90980-11153; you can get them either from the dealer or Ballenger Motorsports. Yours will be both gray and brown; they are only available in gray now. It won't make a difference.

You should get new terminals and seals (get the black ones, the brown and green ones are for different wire sizes); Ballenger has them. The old seals are too old to be reused and you can't install the seals with the terminals crimped onto the wires. You'll only lose 1/4", if you're careful, and there's more slack than that in the harness.

 

[JohnnyLX570]

The time has come to go from forum lurker, to a contributing member of the land cruiser society. (I know I'm here asking a question, but trust me, I have stuff to provide I haven't seen here yet!) Anyways, the rig in question is a 1995 FZJ80R, UK import and my ownership has just made 1 year last month. From as early as I can remember in my ownership it has not idled or run 100% smooth like a straight-6 should and I would like to try and get a collective input on this as I have already done lots of troubleshooting (detailed below). The best description I have for the problem is the engine is kinda puttering, most noticeably from the exhaust. It can just barely be felt with a hand on the valve cover. The only possible clue I have is a rare CEL for codes 24 and 31 IIRC. Those are IAT and VAF circuit codes, checked connector on airflow meter as it contains both sensors and found nothing wrong. It comes on from time to time but clears when the truck is shut off for a small length of time. Doesn't return for days or weeks, haven't identified any conditions causing CEL, and nor do the operating characteristics change when its illuminated either. The truck does this warm and cold, and throughout almost all of the RPM range from what I can tell. Probably is happening under-way at speed too, but its not noticeable when driving so I can't say.

Lastly, a quick piece on what the PO messed up before I bought it, just in case this carries any significance... PO said he tried to replace the plugs and wires but had problems with #5 and there's "something wrong with that plug." Turns out he just yanked the end of the plug wire off and it stayed on the #5 plug, but instead of going down to HF and getting long pliers to fix it, he just put it back together misfiring on #5. This persisted until I drove it home and figured out the problem in 10 minutes.

Troubleshooting I have tried:
-New Plugs & Wires
-All vacuum lines replaced
-Throttle Body cleaned (with new gasket)
-new Aisin coolant temp sensor
-IAC "reset" by cycling key from off to on 14x (noticeable effect, but not fixing my issue)
-EGR disabled (modulator was broken by PO, capped vac source lines to disable. UK ecu has no EGR check sensor anyway)
-Tried "unsticking" EGR by rapping on it with screwdriver handle while applying vacuum to the actuator, no change
-mechanics stethoscope on all injectors and nothing seemed to be suspect (4,5,6 are hard to get to, clicking was weaker but I was in quite a position and could be the reason)
-Checked engine wiring harness for common rub thru near supporting bracket, and heat damage from EGR (RHD wiring goes a different path away from EGR.)
I could have incorrectly checked this, or checked at a wrong location as it is mostly known on LHD models. A RHD weak point could still exist?

Other work done that's probably not related but could be:
-New Fusible Links
-CDL Switch
-New Intake Boot
-New Fuel filter on block (by PO, looks new)
-New Cap and Rotor (by PO, checked by me, seems fine)

I've done quite a bit of work to this rig in the year I've had it, but this non-smooth running issue and a weird squeak in the rear are going to drive me crazy, the squeak I can live with eventually but I do want to know what the engine problem is before I head out on a trip to MOAB later this summer. My dad recently picked up a LX450 and says it also exhibits this behavior, but I haven't seen it in person yet to truly confirm this. If anyone has any ideas at all I would love to hear them, please get some suggestions flowing and maybe we can figure this out and get my straight-6 running like one!

I was going to say check your vacuum lines, but you said they were replaced. My independent Toyota specialist replaced mine on my 2004 supercharged Tacoma, but it still sounded rough and began to not start off and on, can't have that. Took it to Toyota dealer and they replaced all the lines and said the ones that were on it were the wrong size and were leaking, no problems in 3 years, now my 3 Toys go to the dealership for maintenance, they're not perfect either but they take care of me.

 

[ppc]

I've replaced the O2 sensor with a new OEM part straight from Toyota, and fixed an exhaust leak between the manifold and y-pipe thing. Sadly, to no avail. The battery was unhooked for over 24 hours while I did the job in two sittings and drove my 40 to work, but the sputtering idle still persists. The new sensor definitely looks much nicer, but I am stumped that I can't really tell a difference in the running condition. I'm running out of things to chase, what next? Surely I'd have other symptoms if I was looking at a blown HG or other mechanical damage, right?
View attachment 4119183

After the battery was disconnected the ECM needs to re-establish the running parameters. It takes running few cycles/trips to do so don't overreact. You still may have a problem but don't panic.

 

[petegangies]

Did you inspect the harness side connector for the o2 sensor?

 

[MOcruisin]

Soot is the result of unburnt gas, but you never said what gas you're using, and that will have an effect.

As to the sputtering problem, which I think was the reason for your post, have you inspected the wiring harness leads to the injectors? You can verify the circuits for each injector by connector the injector end of the harness to the ECM end using a DMM. If everything else has been eliminated, this is probably the root cause.

You'll have to remove (at least) the upper intake manifold, and I'd recommend buying (6) of the connector housings, because you will break the latch on at least one, and they will not work with a broken latch. The part number is 90980-11153; you can get them either from the dealer or Ballenger Motorsports. Yours will be both gray and brown; they are only available in gray now. It won't make a difference.

You should get new terminals and seals (get the black ones, the brown and green ones are for different wire sizes); Ballenger has them. The old seals are too old to be reused and you can't install the seals with the terminals crimped onto the wires. You'll only lose 1/4", if you're careful, and there's more slack than that in the harness.

Starting from the top, I'm running the midwest standard 87 low octane gas, nothing fancy.

Injector harness checking will be my next step here, taking the upper manifold off will also let me check for any more vacuum leaks I may have missed under there. I have pretty advanced electrical debugging abilities (am engineer by day), but please confirm with me I have the procedure correct on what I'm supposed to do: I am checking to verify one of the pins in each injector connector has 12V with key on, and the other pin has good continuity to the appropriate pin on the ECM side of the harness. Just simply tracing end to end in continuity mode and looking for a suspicious reading?

Replacing those old connectors is 100% okay with me, although I know of another great source for connectors for all kinds of automotive projects. I have located this connector from Corsa Technic, cross reference checks out, and it comes with terminals and seals (both have 3 size options) for less than the price of the connector alone on Ballenger Motorsports. OEM Sumitomo as well. I used that company to locate all the connectors I needed for a full DIY Speeduino EFI build on a Kei Truck I had in college. I even used denso style ford ranger injectors so I have the crimp tool.

After the battery was disconnected the ECM needs to re-establish the running parameters. It takes running few cycles/trips to do so don't overreact. You still may have a problem but don't panic.

So I have now gone on a trip out of town over the weekend, a couple hours of highway driving and some in town cycles as well, with unfortunately no noticeable change.

Did you inspect the harness side connector for the o2 sensor?

I did when replacing the sensor and doing my exhaust work. The connector is in good shape and the clip is still flexible and holding on well, it gives a nice click when you fully seat the plug too. Inside was clean and wires are still flexible, all seems good here?

 

[Malleus]

Corsa carries some Sumitomo/Yazaki terminals, but not all that you need for and 80 or 100 series truck. It's too much trouble for me to shop around the world for a single item when I know I can get what I need from one source. My time is not inconsequential.

 

[MOcruisin]

Corsa carries some Sumitomo/Yazaki terminals, but not all that you need for and 80 or 100 series truck. It's too much trouble for me to shop around the world for a single item when I know I can get what I need from one source. My time is not inconsequential.

For what it's worth, with my odd homebrew EFI project I reached out to Corsa and they were able to find all the connectors I needed that they didn't yet carry at the time. I often recommend people towards Corsa when they're about to spend $75+ on one singular pigtail for some repair.

I assume I've got the idea right with testing the injector harness though with no comments. I checked through the 1995 FSM and only saw test procedures for the injectors themselves. I'll get the intake gaskets and connectors on order and cross this one off the list too.

 

[Nirajorel]

Got a 93. Ran smooth when I hit the gas pedal but idled poorly during a stop. I’d do a compression test. Mine was an exhaust valve issue.