Need Help 1994 Won't Rev Past 2K rpm

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brownfj80

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May 19, 2026
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cincinnati
Hey guys i'm new to the land cruiser community and need some help. I've got a 1994 FJ80 with what I think is an electrical issue.

When its a cold motor and i start it up without any electrical load on it rev's just fine. As soon as i turn the head lights on bright, push the window buttons, and run the flashers all at the same time while its cold. It revs to 2k rpm with it to the floor and the cuts until it hits 1k rpm then revs back to 2k rpm. It continues to do this until its warmed up and then it does it constantly without any electrical load on it.

I've checked and jumper all the relays on the fuel side along with what's on the ecu side still the same. I checked and cleaned all the grounds that are related to the fuel, ecu and ignition system. No Change. I disconnected the battery while it was running and still the same. I set the throttle to 3k rpm and have shook down the main ecu harness with no change as well.

I did find the main ecu harness chaffed at the egr where the engine lift loop is. It was worn through the shielding on the ignition wiring for the signals from the distributor. No other wiring was worn through.

I'm starting to run out of ideas other than the ecu or trans ecu.

If anyone has any other ideas please feel free to let me know.
 
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brownfj80 said:
Hey guys i'm new to the land cruiser community and need some help. I've got a 1994 FJ80 with what I think is an electrical issue.

When its a cold motor and i start it up without any electrical load on it rev's just fine. As soon as i turn the head lights on bright, push the window buttons, and run the flashers all at the same time while its cold. It revs to 2k rpm with it to the floor and the cuts until it hits 1k rpm then revs back to 2k rpm. It continues to do this until its warmed up and then it does it constantly without any electrical load on it.

I've checked and jumper all the relays on the fuel side along with what's on the ecu side still the same. I checked and cleaned all the grounds that are related to the fuel, ecu and ignition system. No Change. I disconnected the battery while it was running and still the same. I set the throttle to 3k rpm and have shook down the main ecu harness with no change as well.

I did find the main ecu harness chaffed at the egr where the engine lift loop is. It was worn through the shielding on the ignition wiring for the signals from the distributor. No other wiring was worn through.

I'm starting to run out of ideas other than the ecu or trans ecu.

If anyone has any other ideas please feel free to let me
Click to expand...
The symptoms you speak of are kinda confusing. What happens if you let it fully warm up before anything else? Kinda sounds like the AIC is geeking. Will the engine not rev past 2K fully warmed up. Or is it hunting idle? Not 100% clear on what’s going on cause I don’t see a reason why you would run the brights and flashers etc during warm up.
 
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One idea - and it's just that, an idea - is a crankshaft position sensor failing. I had a similar issue about 7 years ago on a BMW M42 engine, where it felt like it would hit a rev limiter and wouldn't go past about 2-3k rpm. Turned out the crankshaft position sensor was coated in oil and crud, and finally was failing. Replaced with an aftermarket one and it actually was worse, it only cleared up after buying the OEM one (could have been a BMW thing).

Anyway. Something to check for gits and shiggles.
 
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brownfj80 said:
Hey guys i'm new to the land cruiser community and need some help. I've got a 1994 FJ80 with what I think is an electrical issue.

When its a cold motor and i start it up without any electrical load on it rev's just fine. As soon as i turn the head lights on bright, push the window buttons, and run the flashers all at the same time while its cold. It revs to 2k rpm with it to the floor and the cuts until it hits 1k rpm then revs back to 2k rpm. It continues to do this until its warmed up and then it does it constantly without any electrical load on it.

I've checked and jumper all the relays on the fuel side along with what's on the ecu side still the same. I checked and cleaned all the grounds that are related to the fuel, ecu and ignition system. No Change. I disconnected the battery while it was running and still the same. I set the throttle to 3k rpm and have shook down the main ecu harness with no change as well.

I did find the main ecu harness chaffed at the egr where the engine lift loop is. It was worn through the shielding on the ignition wiring for the signals from the distributor. No other wiring was worn through.

I'm starting to run out of ideas other than the ecu or trans ecu.

If anyone has any other ideas please feel free to let me know.
Click to expand...
Ok, so i found a somewhat corroded connector on the #6 fuel injector. Just a decent amount of green on the pins of the connector. No white fuzz or anything like that. Just threw it back together and it seems to be running better but still cuts out everyonce and a while.
MissahPapaJ said:
The symptoms you speak of are kinda confusing. What happens if you let it fully warm up before anything else? Kinda sounds like the AIC is geeking. Will the engine not rev past 2K fully warmed up. Or is it hunting idle? Not 100% clear on what’s going on cause I don’t see a reason why you would run the brights and flashers etc during warm up.
Click to expand...
It's not hunting idle.

If you let it fully warm up and press the gas peddle all the way to the floor the engine RPM will not go past 2k and cuts out "like the ecu or ignition shuts off" then recovers after it goes down to about 1200 RPM and continues to cycle like that until you lift your foot off the throttle. It repeats this if you try to get back into the throttle.

the only way i've been able to duplicate the issue when the engine is cold is buy operating all those at once.
 
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majdomo said:
One idea - and it's just that, an idea - is a crankshaft position sensor failing. I had a similar issue about 7 years ago on a BMW M42 engine, where it felt like it would hit a rev limiter and wouldn't go past about 2-3k rpm. Turned out the crankshaft position sensor was coated in oil and crud, and finally was failing. Replaced with an aftermarket one and it actually was worse, it only cleared up after buying the OEM one (could have been a BMW thing).

Anyway. Something to check for gits and shiggles.
Click to expand...
 
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hisandhers80s said:
An 94 fzj80 will not have a crank position sensor. Only 95-97 have tha
Click to expand...

The 993-94 Toyota Land Cruiser equipped with the 4.5L 1FZ-FE engine does not use a standalone crankshaft position sensor on the engine block. Instead, it uses a pickup inside the distributor to handle both engine speed and position signals.
 
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A 93-94 does not use a MAF- mass air flow sensor. A VAF or AFM - depending on terminology, is used. As long as you haven't messed with the screws at the connector, I don't think that is your problem. Have the Cap, Rotor and Wires been replaced? What does the inside of the dizzy look like? Has timing been checked with a light?
 
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ppc said:
A 93-94 does not use a MAF- mass air flow sensor. A VAF or AFM - depending on terminology, is used. As long as you haven't messed with the screws at the connector, I don't think that is your problem. Have the Cap, Rotor and Wires been replaced? What does the inside of the dizzy look like? Has timing been checked with a light?
Click to expand...

ppc said:
A 93-94 does not use a MAF- mass air flow sensor. A VAF or AFM - depending on terminology, is used. As long as you haven't messed with the screws at the connector, I don't think that is your problem. Have the Cap, Rotor and Wires been replaced? What does the inside of the dizzy look like? Has timing been checked with a light?
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Cap and Rotor Haven't been replaced yet. Inside of Dizzy was good.

I took the whole engine harness off yesterday and found this down at the transmission. After I spliced the bad pins together the problem kinda change a bit. Now without any electrical load i can keep it running without the RPM fluctuating.

IMG_0156.webp


IMG_0155.webp
 
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brownfj80 said:
Cap and Rotor Haven't been replaced yet. Inside of Dizzy was good.

I took the whole engine harness off yesterday and found this down at the transmission. After I spliced the bad pins together the problem kinda change a bit. Now without any electrical load i can keep it running without the RPM fluctuating.

View attachment 4147070

View attachment 4147071
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I’d put money on that corrosion in there is up into the wire jackets you can do one of three things
( 1 ) de-pin all the affected ones and cut back the jackets get some 3:1 heat shrink and clean the oxidation off. ( not the best way )
( 2 ) Or de-pin the effected ones and splice in new ones ( highly suggested )
Find a new or used connector and splice it in ( meh )

You can try to hit it with some electric parts cleaner and re-connect the two ends multiple times each time respraying the electric parts cleaner till you start to see results blow off both connectors and see if anything gets vastly better. If it does you’ve found your problem but you’ll still likely need to repair the connectors ( jam some dielectric grease in there for good measure after repairs )
 
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