1992 4Runner 3VZE - Crank, Wants to Start, No Start - Code 14 Troubleshooting Help

[the_white_shadow]

I picked up 1992 4runner with the 3VZE 3.0l Auto 4wd a few weeks ago and i am now trying to get it running. Back story is that it sat for 10+ years, maybe more, and the reason it was parked was due to a bad transmission. PO supposedly swapped in a junkyard transmission but it still "wouldnt run right" so they parked it. Completely stock as far as i can tell. It has the tow package and 4.88s.

First attempt to start it was just throwing a battery and seeing what would happen. Turns out it had a broken timing belt. The 3.0 is a non-interference engine so no worries there. I replaced the timing belt, water pump, tensioner, etc and quadruple checked timing and all is good there. Currently the front cover is off the engine so i can keep check on timing, so no other accessories are connected to the engine, i.e alternator, PS pump, etc. Battery is fully charged.

I am using a temporary fuel system as the has tank looked like it could have been on the Titanic. Pump laying in the bottom, holes in the top, etc. Kind of surprising as the rest of the 4runner is basically rust free. So my temp fuel system is a walbro 255 inline pump running out of a gas can to the factory fuel feed line to the fuel rail. Return line is to a separate gas tank. It has plenty of pressure at the rail.

Currently it will try to start for 1-2 seconds then die. I pulled the code from the ecu and it is flashing a code 14, which means the igniter isnt talking to the ECU and/or vice versa.

CEL is on with the key on and while cranking. When it tries to fire for the 1-2 seconds, its goes off. I have cleared the code by pulling the EFI fuse numerous times. No change.

I have replaced the coil. No change.

I have ran jumper wires from the IGT and IGF wires on the igniter directly to the IGT and IGF wires on the ecu to bypass any potential breaks/shorts in the wiring. No change.

I ran a jumper for the IG- wire (green wire) on the distributor to the ecu. No Change I plan on doing the same with the other 3 distributor wires. Also distributor coil pickups are confirmed good with ohm meter. Distributor was pointing correctly when checking for timing.

Put a ground directly to the igniter to the battery. No change.

Swapped out AFM with a known good one. No change. I havent ohm tested either one though.

Im running out of ideas. I bought a cheap Chinese igniter on Amazon that should be in tomorrow to try out. I am going to order new gas tank, pump, etc, but i dont think thats the problem.

Is there some type of security bullshit on these? I removed the aftermarket alarm from under the dash along with 10lbs of wiring that was scotch locked under there. I have no fob or anything. Just a plain key. Could it be a neutral safety switch? Tried to start it in neutral and same.

Clearly the ECU isnt telling the injectors to fire, as i can put some starting fluid into the intake tube and it will try to run longer.

Thoughts?

 

[the_white_shadow]

I hate throwing parts at shit, but since this thing sat for a decade or more, figured id buy some tune up parts for it. One thing im holding out on buying is the MAF.

Just bought:
Fuel tank with sending unit, pump, fuel filter, etc
New fuel regulator
spark plugs, wires, dizzy cap and rotor

It does need a new radiator too as the one in it is so caked with rusty shit, but i think i may have something on the shelf that will work.

 

[the_white_shadow]

No update. I re-did the ground at the battery terminal with a new copper crimped end and upsized the fender to battery ground. No change. Checked all the grounds on the engine and they look fine. At this point im hoping its the igniter, but we will see.

 

[rattlewagon]

I have a couple of MAFs, what numbers are you looking for?

 

[Chkn]

I suspect you have an issue either with the IGT or IGF circuits. IGT is the ECU telling the igniter what to do and the IGF is the igniter telling the ECU that it fired the coil. If you have a problem with either circuit the engine won’t run.

Do you have an oscilloscope, it makes diagnosing IGT/IGF a lot easier.

 

[the_white_shadow]

I have a couple of MAFs, what numbers are you looking for?

Id have to check the number i have on mine.

 

[the_white_shadow]

I suspect you have an issue either with the IGT or IGF circuits. IGT is the ECU telling the igniter what to do and the IGF is the igniter telling the ECU that it fired the coil. If you have a problem with either circuit the engine won’t run.

Do you have an oscilloscope, it makes diagnosing IGT/IGF a lot easier.

This is what i have been seeing as well. I ran jumper wires directly from the igniter IGF/IGT wires to the IGF/IGT wires on the ECU to bypass the original wires in case of cracked/broken wires under the intake. No difference. I was really hoping that would work but negative.

I dont have an oscilloscope.

 

[Chkn]

My next guesstimate would be an ECU or ignitier issue, probably can’t send/receive the IGT/IGF signals. Without an oscilloscope it’s time to go cheapest to most expensive. 🤣

 

[the_white_shadow]

My next guesstimate would be an ECU or ignitier issue, probably can’t send/receive the IGT/IGF signals. Without an oscilloscope it’s time to go cheapest to most expensive. 🤣

Exactly. First was the coil. Now im trying a cheap chinese igniter. Next will be the MAF, but i dont think thats it. I havent cracked open the ECU but externally it looks like new. Im pretty sure i was the first to remove it from its factory spot behind the kick panel.

 

[Chkn]

Might have swollen/leaky capacitors. Starting to see more 90s electronics crap out. Buddy of mine had to have his 96 4Runner 5VZ ECU repaired because it had similar issues.

 

[the_white_shadow]

Might have swollen/leaky capacitors. Starting to see more 90s electronics crap out. Buddy of mine had to have his 96 4Runner 5VZ ECU repaired because it had similar issues.

Definitely a possibility. I had a 92 SC400 that had that issue with its ECU. Had to send it off to get repaired.

 

[Lbhsbz]

I have a fair amount of experience with this after spending a long time trying to catch an intermittent a few years ago.

Per toyota strategy,

The IGT signal triggers the igniter power transistor. Without IGT,
spark will not occur. The IGF signal confirms that an ignition event
has occurred. Without IGF, the ECM shuts down injection pulses.

On older systems, if engine will not start due to missing IGF, injectors
will pulse once or twice during cranking.

Sounds like this is what's happening. I'd stop at this point and pull the ECM...Take a look at the coil driver transistors. I've seen more than a few let the smoke out, which is why no IGT signal, and therefor no IGF signal. Potato pic of blown transistor

 

[the_white_shadow]

I have a fair amount of experience with this after spending a long time trying to catch an intermittent a few years ago.

Per toyota strategy,

The IGT signal triggers the igniter power transistor. Without IGT,
spark will not occur. The IGF signal confirms that an ignition event
has occurred. Without IGF, the ECM shuts down injection pulses.

On older systems, if engine will not start due to missing IGF, injectors
will pulse once or twice during cranking.

Sounds like this is what's happening. I'd stop at this point and pull the ECM...Take a look at the coil driver transistors. I've seen more than a few let the smoke out, which is why no IGT signal, and therefor no IGF signal. Potato pic of blown transistor

Thanks for the info. Ill pop the cover on the ecu this afternoon to see if anything looks out of the ordinary.

 

[the_white_shadow]

No visible damage or leaks inside the ecu. Forgot I have another 3vz ecu (different number) on the shelf. Popped it in and same thing. I’m really hoping it’s the igniter which comes in tomorrow.

 

[Lbhsbz]

No visible damage or leaks inside the ecu. Forgot I have another 3vz ecu (different number) on the shelf. Popped it in and same thing. I’m really hoping it’s the igniter which comes in tomorrow.

Do you have a scope or graphing mulitmeter? (like an old school snap-on vantage?)

 

[the_white_shadow]

Do you have a scope or graphing mulitmeter? (like an old school snap-on vantage?)

Nah. I’m not that fancy.

 

[the_white_shadow]

New Chinese igniter made no difference.

 

[Chkn]

How’s the pin fit at the ECU and the igniter? Possibly have a loose terminal or two.

 

[the_white_shadow]

How’s the pin fit at the ECU and the igniter? Possibly have a loose terminal or two.

It’s pretty tight. I checked every connection I could.

 

[Lbhsbz]

Did you open the ECM yet?

 

[the_white_shadow]

Did you open the ECM yet?

Yep. Everything looked good inside. No swelling or blown capacitors. Swapped it for another one I had on the shelf and no change.

 

[Skinny]

It's been decades since I've touched a 3VZ but my advice really doesn't relate specifically to just this engine.

You need a manual and you have to work the troubleshooting chart. You are getting well into a parts cannon solution and using non-OEM stuff too.

Work the problem and stop guessing. You took the time to run jumper wires to bypass the harness when testing for the correct signal or doing a resistance test between the ECM and igniter connectors would have given you the same result.

 

[MDNyota]

Check the MAF wiring for visible signs of a short and the intake tube behind it for any cracks. I've had both issues before that caused it to fire and run for a few seconds and promptly die. Might not be your issue but it's an easy thing to inspect.

 

[Skinny]

I would venture to say if it has an IG signal failure that it's something in that small closed circuit that goes out and back to the ECM and not much else. Unless of course there is a reason the spark is being shorted in the dizzy which may mess with that signal.

Anything else would most likely not throw that code.

 

[the_white_shadow]

a non-update: Installed new fuel tank with pump, sending unit, fuel sender, fuel filter, and regulator. No change. Did a cheap tune up on it with plugs, wires, rotor, and cap. No change. Pulled the intake tube and some nasty unburnt fuel was coming out of the intake and throttle body. Cleaned that out best i could and tried to start it. It backfired out the throttle body and caught itself on fire (briefly). So i checked timing again and it was spot on with the timing marks on the cam and the crank pulley at 5deg BTDC as per the FSM. Im now leaning to a stuck valve or something. I plan on doing a compression test (which i should have started out with anwyays) to see if i have any dead cylinders. Looks like its probably going to be sold as is if i cant get it to start. I definitely dont want to 3.4 swap it.