FZJ80 Running Woes (1 Viewer)

BakerFJ

Benny Bodangus
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136
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Hey what's up y'all. Been chasing a running issue on my 93 FZJ80 for awhile.
The issue started as intermittently running like it was firing on half the cylinders, with no acceleration or power at all. At the time it was giving codes for the IAT, VAF, and TPS. Both tested out of spec so I went ahead and replaced them, and no change. After a few days of going through absolutely everything on the Cruiser---all sensors tested good, swapped in a spare ECU, the works. I did find my rear knock sensor connector was unplugged, it crumbled to pieces in my hand, and the wire was broken. Went ahead and pulled the harness assuming that was my underlying issue and went through the whole thing end to end, all new connectors, terminals, and weather seals, and replaced any wires that had become brittle or dogged from the heat.
Got everything back together last night and she started right up, however on my test drive, I found I had no acceleration under load. I can accelerate from about 0-20% throttle, albeit poorly, and anything beyond that it just bogs down. Now I'm just getting codes 24 and 32 for the IAT and VAF. Pulled out my reman unit and retested, and all was in spec. Even taped the crap out of my intake boot in case I had a vacuum leak but still no change.
SOO at this point I'm at my ABSOLUTE WIT'S END as I have no idea as to what the issue could be.
I will note, my fuel pump regulator is making a loud ticking noise, which is new to me. However during my initial testing/inspection I had proper fuel pressure, so don't know what that's about, although it is a red flag to me.

Anyways, if anyone has some input it would be greatly appreciated as I'm beating my head against the wall at this point. Gonna try to find a known good used VAF locally to swap and see if anything changes, but at that point I would just be throwing parts at it in hopes I find the issue.

Maybe I should just LS swap it :p

Here's some pics of the wiring harness, all new loom and Raychem DR25 heatshrink everywhere I could, anything else is Tessa taped. Even relocated the O2 wires as I have mine installed at the exhaust manifold. I'm involved in a lot of racing/motorsports so this is the base standard of any wiring I typically do. If it were a fully custom harness I would've ran service loops but didn't see a need to since I wasn't redoing every single wire
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effjay80

SILVER Star
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Northern Colorado
Do you possibly have access to a known good VAF to plug in and try? Was the VAF you're using ever installed in the truck when it ran correctly?
 

BakerFJ

Benny Bodangus
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Messages
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Austin, TX
Do you possibly have access to a known good VAF to plug in and try? Was the VAF you're using ever installed in the truck when it ran correctly?
Trying to source one currently, so to answer the question, no. When I install the old VAF it actually runs worse. I have a stack of bad VAFs, they are the bane of my existence 🤣 Until I get another, all I can do is retest the wiring from the VAF to the ECU to reinsure there's no breaks in the wiring, and swap ECUs again. But given the symptoms I'm experiencing I have a hunch it's going to be related to the VAF.
 

effjay80

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282
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My VAF is the one that came with my vehicle in 1994 and makes me very nervous so I bought a remanufactured unit in hope of having a backup. It tested as okay according to the FSM procedure but would not actually work when installed. Pretty much same symptoms as you describe. Plugged back in my stock VAF and immediately away we went which is where I am now.
 

BakerFJ

Benny Bodangus
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Messages
136
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Austin, TX
My VAF is the one that came with my vehicle in 1994 and makes me very nervous so I bought a remanufactured unit in hope of having a backup. It tested as okay according to the FSM procedure but would not actually work when installed. Pretty much same symptoms as you describe. Plugged back in my stock VAF and immediately away we went which is where I am now.
This is relieving to hear, because if it's not the VAF I'll be at the point of just bringing it to the local Land Cruiser Specialist shop here in town. I know there's a BMW business that does a good job rebuilding our VAFs, however it's quite spendy. I mean if it is my VAF in the end I'll just bite the bullet and send one (of my three other broken VAFs lol) off to be rebuilt as a spare. Or possibly start looking into converting to a MAF sensor---read a write up on the conversion a while ago, I believe its a kit from Russia
 

effjay80

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I sent my spare non functional unit to Bavarian Restorations and it was deemed to be not repairable. I believe the soldered contacts were destroyed and were the issue.

I not 5 banana wrench expert but just sharing my similar experience. If my functioning unit ever goes I plan to NOT open it or touch the sacred screws but send it intact to Bavarian and believe it could then be repaired.

Hope you get figured out.
 

BakerFJ

Benny Bodangus
Joined
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Messages
136
Location
Austin, TX
I sent my spare non functional unit to Bavarian Restorations and it was deemed to be not repairable. I believe the soldered contacts were destroyed and were the issue.

I not 5 banana wrench expert but just sharing my similar experience. If my functioning unit ever goes I plan to NOT open it or touch the sacred screws but send it intact to Bavarian and believe it could then be repaired.

Hope you get figured out.
Picking up a roof rack/awning from the Land Cruiser Specialty shop up the street from me in the AM tomorrow (I know, I know, why buy accessories for a rig that doesn't run. If I were a logical individual I wouldn't daily a Land Cruiser, but here we are), going to see if they have any VAF units I can borrow/buy, or have them throw mine on another Cruiser and see what happens. Just finished double-checking the continuity of the wiring from the VAF connector and the ECU and it all checked out, even swapped ECUs with my spare to see if anything changed and still has the same problem. Quite the rabbit hole but I've seemingly eliminated everything else.

If it does end up being the VAF as I suspect, I'll be tempted to send Bavarian Restorations multiple units from my VAF scrapyard lmao

Side note to myself, I don't think I've checked the IACV, although it only serves it's purpose during idle, but don't want to throw it off the list. I've seen crazier things in my time.
 

BakerFJ

Benny Bodangus
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Update:
Have not found the source of my problem yet
Retested contuity between VAF and ECU, all good
swapped ECUs, no change in running, although a change in the CEL, prior I had codes 24 and 32, now showing 24 and 31, (31 and 32 are pretty similar, both are for VAF signal. 32 indicated open circuit in E2 or short between VC & VS. 31 indicates open between VC & VS or short between VS & E2. The code causes are opposite of one another, and at this point I'm 97.65% sure its not actually a VAF related issue).
Have not sourced a known good unit to swap over, however I don't feel like that's going to solve anything. My bench test on the VAF was 100% within FSM spec.

Tested TPS parameters on the car, it DID test out of spec. Came to realize I've been adjusting it wrong for 6 years, you are NOT supposed to place your feeler gauge between the stopper and plunger on the throttle body backside, there's a (much easier to access) metal stopper at the top backside. With that realization, I reset the (new) NTK TPS sensor, had some tests reading OL when it shouldn't, put on my old Toyota sensor and went through the same adjustment procedure. frickin' mint.
This smoothed out the idle a noticeable amount in park, however once under load (driving) my symptoms did not change.

Feels like the ECU is attempting to compensate or override something. As if there's a super low rev limiter placed on the car that wont allow me to accelerate.

O2 sensor resistances are good, although they are blackened with soot (thanks bad valve seals). Although this wouldn't HELP the car run well, It's not the source of my issue, I'll save swapping those for a later time.
Should also be noted I don't have cats, so no possibility of them being clogged. Ultimate catalytic convert anti-theft! Can't make money off my cats if I already sold them LMFAOOOO. They were going bad years ago and I just got rid of them, slightly regrettable as my exhaust is stinky, but F it.

Burped the truck in case I had a massive air pocket causing the ECT to throw it in cold loop, nothing happened. HOWEVER I forgot to turn on my rear heater, d'oh! Will circle back to that next time. Pulled the ECT sensor and bench tested it in boiling water and graphed its resistance points, it was fine. Picked up a replacement anyways on my way home from class, so will throw the new one in regardless. I do love me spare parts!

All that's left is the IACV and fuel system. I've previously tested fuel pressure at the rail, 45 psi key on engine off, 38 psi @ idle. Healthy numbers, the pump, sock, and filter were replaced about 4 years ago. I've also had the injectors cleaned and flow matched since then. The FPR is original, and during all this has occasionally made a very loud ticking noise. This is a red flag to me, perhaps it's not getting proper vacuum from the gas filter at the intake, over pressuring, or under pressuring. In any event, I'll probably go ahead and overhaul the fuel components, It's not too expensive and will further rid of what could be the issue. Not normally one for shooting my parts cannon at vehicles, but I see it as normal maintenance anyways.

That leaves me at the IACV. At idle I noticed a hissing sound around the throttle body, like a vacuum leak. A vacuum leak would explain everything, although I've previously smoke tested and didn't find anything. It's possible the IACV is stuck open, and leaking vacuum internally to the housing. I'll go back with another smoke test, but I'll pressurize the intake with about 10 psi of pressure to mock loaded conditions. A normal smoke test won't necessarily find those super specific leaks, such as the intake bellows that only open up when the engine is flexing under load. (My intake tube is currently mummified with duct tape lol, although I did not see any cracks in it).

Beyond IACV, fuel system overhaul, and pressurized smoke test, I'm out of things to test haha. So hopefully will find the problem soon!!
 

BakerFJ

Benny Bodangus
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Messages
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Update; fuel injector 1 terminal wasn't seated fully to the ECU plug. Fixed that, and then would only crank and not start. Read codes; AFM, TPS, and ECT. A bunch of coolant came out upon removing the throttle body so I jumped +B and FP to hit the fuel pump with 12v directly so I could burp the truck.

Note: TPS is good, AFM is good, wiring from both to the ECU is good.

Truck starts and idles without needing to hit the FP with 12v after burped, however without that jumper it dies immediately from any throttle. It revs freely with 12v to the fuel pump. Either way while idling it's misfirey and backfires a bit.

Also, if I unhook the fuel pressure regulator from vacuum, nothing changes.

Also aslo, the exhaust pipe is spitting out black soot. May be leftover from all the diag crap I've been doing, may be from something going on with the fuel system. Something for me to keep in mind.

Sprayed all the intake stuff with brake clean to monitor for vacuum leaks but came up with none, of course I shortly ran out of brake clean so might've missed it if it is there, although it'd have to be a pretty big leak.

I'm gonna circle back in the morning, was working at the racetrack all weekend and I'm coasting on autopilot hahaha.

Have all new fuel system parts on the way regardless, as they haven't been gone through in about 5 years😬😬

This diag has been quite the journey, so close though! I better get 15+ mpg after all this baloney😂😂😂
 
Joined
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I feel your pain. My truck used to be so peppy. I was then talked into swapping my injectors to the 12 hole versions. I was going to send my stock ones out and have them gone through but went this way instead. Since then my engine has been a dog. No power. Terrible mileage. I don’t think it’s from the injectors per se, but a disturbed wire, sensor or vacuum leak as you likely have (since the intake manifold had to come off). Hoping you get it sorted. It likely will be something simple/dumb.
 

BakerFJ

Benny Bodangus
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Messages
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I feel your pain. My truck used to be so peppy. I was then talked into swapping my injectors to the 12 hole versions. I was going to send my stock ones out and have them gone through but went this way instead. Since then my engine has been a dog. No power. Terrible mileage. I don’t think it’s from the injectors per se, but a disturbed wire, sensor or vacuum leak as you likely have (since the intake manifold had to come off). Hoping you get it sorted. It likely will be something simple/dumb.
I've been through the engine front to back, even pulled my (just rebuilt) harness off last night to retest the wiring.
I'll put the FPR, Fuel filter, pump, and sock in on Wednesday when they come in.
I will say, I didn't replace any of the metal gaskets when I pulled my upper intake/TB. But in my experience as a racecar mechanic you can get away with that, I'm gonna do a pressurized smoke test leak just in case.
At this point, after fixing a multitude of things, all that's left is fueling or vacuum leak. But it'd have to be a massive vacuum leak, which wouldv'e shown itself with the brake clean.
Is what it is, I'm thankful I have the experience needed to tackle this. 4 years ago I would've been so far in over my head😂

It's always something stupid. Watch it be bad fuel😂😂 (I did check to make sure there was no water in the tank just in case)
 

BakerFJ

Benny Bodangus
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Messages
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Also want to add, in an earlier update I noted that I could hear a vacuum leak sound from the TB. It was just one of my vacuum ports looped back into itself, no leak. It was sucking a crap load of vacuum through the hose. Was surprised at that amount of vacuum, if I pulled the hose off and put a small piece of paper in front of it, it probably could've sucked it in lol. I suppose that's a good sign, nothing to do with my issue though
 

BakerFJ

Benny Bodangus
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Messages
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Installed the new fuel system components, although I had good fuel pressure before so I didn't expect it to fix it. Obviously nothing changed lol.
I guess all I have left that I can go over is the fuel pump relay and circuit opening relay. Beyond that I'm like this 👌 close to dropping it off at the Land Cruiser Specialist, cause I've quite literally gone through everything. Unless it's something crazy like the distributor jumping a tooth or god knows what😂😂
 
Joined
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Do you have a scan gauge? I notice that my timing gets pulled a lot when I feel low power. Might check yours as well then hunt down what systems or sensors couldn’t influence that. At least that’s where I’m at. Also.. my TPS only reads 75% even when at WOT. Prob unrelated.
 

BakerFJ

Benny Bodangus
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Messages
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Do you have a scan gauge? I notice that my timing gets pulled a lot when I feel low power. Might check yours as well then hunt down what systems or sensors couldn’t influence that. At least that’s where I’m at. Also.. my TPS only reads 75% even when at WOT. Prob unrelated.
Well that's where this whole thing gets complicated because I'm OBD1. If I were OBD2 I could just do live data and see exactly where my issues lie
 

BakerFJ

Benny Bodangus
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Messages
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Tested Circuit Opening Relay and Fuel Pump Relay off-car, both tested good.
Symptoms have slightly changed since new fuel system components were installed;
When I go to start, it starts and runs great for about a second and dies, almost as if it is turning itself off. Same thing when I apply 12v to the FP from the diag port whereas before it would run with it jumped. Interesting.
(In normal not broken conditions) the FP gets a full straight 12v when the key is in the 'start' position (ign triggers COR), then defaults to the COR circuit, controlled by the VAF per my understanding, where it then runs through the FP Resistor. If the VAF FP switch isn't triggered/functioning, then the FP won't receive voltage as soon as the key goes from 'start' to 'run' position, as the smaller secondary coil in the COR won't be keeping the switch closed.
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Going to test the full fuel wiring circuit for proper functionality through and through, seeing as applying 12v to the FP previously worked.
However, I can feel fuel running from the pump when I go to start and for the 1 second that it runs, after it dies, the fuel pump continues to run as well.
If I can't figure it out this week, my buddy and I are gonna take it to his shop where we'll have access to a plethora of diagnostic equipment, and more space than my two-car garage.
I think at this point it would be beneficial to backtrack a bit and go over the basic stuff again.
Given I have codes for AFM and TPS, I'll retest those. Along with that, I have spare (new) plugs, it's possible I fouled the old ones, however I wouldn't think that to cause a start then die immediately issue, moreso of a poor running condition. But at this point I'm questioning everything, as I've literally been over almost everything.

Before hitting post; VAF retested good, also tested its fuel control circuit which was also good, and the VAF connector has proper ground for the internal fuel control switch.
Pulled spark plugs and they were f******ed off. Likely from the many tests I've been running. They're all super boogered up with soot, which tells me prior to swapping fuel parts that I was running extremely rich (it smelled that way too while running it). plus I slapped in some old plugs as I couldn't find where I put the new ones. 1 & 2 were wet, not sure if it's fuel or oil. Smells like oil, of course the whole plug has old oil on it anyways.. starting from the top is 1 and down to 6. With the new plugs in, for the 1 second that it runs, it runs really smoothly! Good sign I suppose lol
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I'm going to look into what could cause the engine to cut itself off and report back with updates
 

BakerFJ

Benny Bodangus
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Update to my update's update's cousin's mother's update
-New plugs installed
-TPS re-readjusted and ensured to be dead tits perfect, and double checked, and triple checked.
-Still would die shortly after startup.
-Tightened throttle cable, now starts and runs. Hence why it would die after startup before. Shaking my head at my 30 year old stretched and sloppy cable. I had ordered a new one preemptively, but it was the wrong length, that's what I get for cheaping out and getting a non-Toyota part hahaha
-Dialed in the ignition timing (at least I think so, the sloppy cable might be affecting this)
Truck runs and drives, however something's still wrong. Its not running smooth and super down on power.
Also, nothing happens if I floor it while driving, figured I'd mention that.
The truck has had these exact symptoms in the past, wish I remembered what it ended up being. Most times it's TPS, VAF, or needing a tune-up. I'll throw my old wires and cap on and see if anything changes, although I should just get new ones. Figured I'd do that after fixing whatever's going on with it.
Pulled the new plugs after a drive up the street and back, #2 was wet again. Makes me wonder if this final issue I'm chasing is a simple gnarly misfire. Pulled the dizzy off as I noticed it was leaking a lot, had the O-ring on the shelf so I'll throw it back together tomorrow as it's late now and I realized I don't have a socket for the crankshaft to get er at TDC. Will revisit tomorriw
 
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I have nothing to suggest regarding your problem as you are way beyond my ability. I am a new owner of a 97 LC that I think I may have a fuel pressure issue; assumings yours is the same, where to you hook up a fuel pressure gauge and what sort of adapter is needed. Thanks and good luck with your further trouble shooting.













lc
 

BakerFJ

Benny Bodangus
Joined
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Messages
136
Location
Austin, TX
I have nothing to suggest regarding your problem as you are way beyond my ability. I am a new owner of a 97 LC that I think I may have a fuel pressure issue; assumings yours is the same, where to you hook up a fuel pressure gauge and what sort of adapter is needed. Thanks and good luck with your further trouble shooting.













lc
I appreciate the kind words! Five years as a race car mechanic will do that to ya, without that experience I'd be way in over my head 😅😂

You can test fuel pressure at the rear banjo bolt on the back of the fuel rail. It's kind of a bugger to get at but it's the easiest way, when you do it make sure to get reference pressure at idle by disconnecting the fuel pump regulator from vacuum, then reconnect it and take that pressure. If the fuel regulator is bad you probably won't see a change, if the regulator isn't sending fuel back to the tank you'll see high pressure, if it's stuck open you'll see low pressure. Full disclosure, I'm regurgitating that from what one of my buddies told me so I would look into it to verify. The FSM also outlines testing fuel pressure with key on engine off, if you need I can post up the procedure from the manual. Reference pressure is an extra step than what Toyota outlines.
I used the OTC fuel pressure testing kit, make sure to use crush washers when you test too.
You can rent it from Autozone I believe, I borrowed mine from my buddy.
 
Joined
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Rockport, ME
I appreciate the kind words! Five years as a race car mechanic will do that to ya, without that experience I'd be way in over my head 😅😂

You can test fuel pressure at the rear banjo bolt on the back of the fuel rail. It's kind of a bugger to get at but it's the easiest way, when you do it make sure to get reference pressure at idle by disconnecting the fuel pump regulator from vacuum, then reconnect it and take that pressure. If the fuel regulator is bad you probably won't see a change, if the regulator isn't sending fuel back to the tank you'll see high pressure, if it's stuck open you'll see low pressure. Full disclosure, I'm regurgitating that from what one of my buddies told me so I would look into it to verify. The FSM also outlines testing fuel pressure with key on engine off, if you need I can post up the procedure from the manual. Reference pressure is an extra step than what Toyota outlines.
I used the OTC fuel pressure testing kit, make sure to use crush washers when you test too.
You can rent it from Autozone I believe, I borrowed mine from my buddy.
Thanks so much for your detailed reply; I have ordered a FSM which should be here in few days so won't need your generous offer to send me a copy of the procedure to measure fuel pressure. I am having an intermittent hot start problem so fuel pressure drop after engine shut off seems a good issue to check. Thanks again. The car has 289k miles and seems to have the original fuel pump. Do you have an opinion as to whether leaking fuel injectors could be an intermittent problem?
 

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