3vze Dying While Driving
- Thread starter JunkCrzr89
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Hey all, was about to make my own forum post about this exact issue with almost the exact same symptoms in my 89 4runner. Only difference is none of my fuses are melting, I'm sure there are likely to be other things melting given the neglect this car has faced before I owned it. Fortunately before this issue arose she ran perfectly fine which leads me to believe this should be reversible and survivable. Only things that may be of concern, there was a new distributor, alternator, and spark plug wires installed by previous owner. All have worked just fine until now. I recently put in a new battery and the battery as well as the alternator are tested to be working. Symptoms for the issue are similar, cold starts normally within 1-3 seconds of key turn and I can take a 20-30 min trip. Problems arise if I want to start once warmed up, coolant and oil temps seem to be in normal range but it will crank and crank and crank and never fire over or give a lone couple of single cylinder fires. If I let it sit for 45 mins to an hour it will have a VERY rough start misfire all over, throw a check engine for a while, and then run fine once fully warmed up and idling again. I can take that 20-30 min trip back home and then the check engine light will not come back on next cold start.
I am planning on pulling fuel injectors and putting in new o-rings and cleaning/testing them as well as: checking fuel flow to rails (just replaced fuel filter), replacing all injector plugs from wiring harness (they are disintegrating), and replacing vacuum lines. Hopefully doing these can at least give peace of mind that they are not adding complications to the 30 something year old 3vze black magic that makes it do what they do.
Is there anything else I should be doing to try to attack this issue? Would like to have my beautiful 4r back as this problem only arose a few weeks ago. Did OP ever diagnose or repair the issue?
I am planning on pulling fuel injectors and putting in new o-rings and cleaning/testing them as well as: checking fuel flow to rails (just replaced fuel filter), replacing all injector plugs from wiring harness (they are disintegrating), and replacing vacuum lines. Hopefully doing these can at least give peace of mind that they are not adding complications to the 30 something year old 3vze black magic that makes it do what they do.
Is there anything else I should be doing to try to attack this issue? Would like to have my beautiful 4r back as this problem only arose a few weeks ago. Did OP ever diagnose or repair the issue?
JunkCrzr89
Competent Ignoramoose
- Thread starter
- #23
EFI relay was bad. Replaced it and zero issues since. Would be worth stopping by your local chain auto parts store and picking up one for $20 and giving it a try.
Gave the EFI relay a shot and it unfortunately did not solve my problem. I was hoping it would help but I also do not have any melting fuses which led me to believe something else might be having issues. I actually tore into my AFM today and discovered two broken solder connections on pin 2 and 3 (E1, and E2). I resoldered those back together and tested my AFM readings as per the manual and everything seems nominal or close to it. I should have but did not test readings before; but in looking at the pages in the manual it says there are different values based on ambient temperature: aka, warmed up vs cold start.
After messing with the AFM it cold started fine again but I have yet to go on a longer test drive to replicate symptoms.
I’m having the same issues. Just got out of the shop a couple days ago after I personally replaced fuel pump, filter, and checked EFI relays and fuses. I got it towed to the shop and the mechanic said it was an injector problem. So here I am after having the shop replace all the injector lines and other associated parts and I start driving it to my house. Not 10 miles in it croaked again. I’m at a dead end, any ideas?
If you feel comfortable doing so, open up your Air Flow Monitor module. I scraped the silicone out of the top and once inside it was pretty obvious that there were a few broken solder joints which I fixed. I just used grey rtv to re seal the top after fixing. After that mine has only had one hiccup where it got hot and shut off on me but it seems that the broken solder joints allowed for cold starts but would read the temperature sensitive resistor inside incorrectly and it basically tells the ECU to give no more spark. If there were any other moments where it didn't want to fire over I would pop the hood open, unplug the AFM, and plug it back in and it would start up perfectly fine. It's practically free to open up the AFM and see if anything's wrong and something will likely be pretty clear. Clean up with qtips and electrical contact cleaner while you're in there too.
Just for fun you may want to look up the AFM section in the repair manuals and check terminals and resistances with a multimeter. I did not check mine prior to the fix, but after the fix it seems to operate pretty normally. The temperature sensitive resistance circuit is the one you likely want to pay attention to. I would tell you the page in the Haynes but I use a busted pdf version so good luck.
No, I’m not losing fuel. My next guess would be a distributor. Really hoping it’s not an igniter as I’ve seen those go for 500 bucks or more
idk why this has to be said again and again.
test parts and diag the problem, or pay someone to. (except whoever dude paid to diag wrong ...)
throwing parts is never a win.
the FSM is your friend. if you own a vehicle like this, you should also own and know your way around a multimeter.
there are mag pickups in the distributor. start there.
typically something dying hot is a failed coil type device or a high resistance problem.
test parts and diag the problem, or pay someone to. (except whoever dude paid to diag wrong ...)
throwing parts is never a win.
the FSM is your friend. if you own a vehicle like this, you should also own and know your way around a multimeter.
there are mag pickups in the distributor. start there.
typically something dying hot is a failed coil type device or a high resistance problem.
I'm sorry, did you read the code when it died? I'm pretty sure you can jump the fuel pump at the diag connector as a way to troubleshoot to see if it stays running to rule out things like the AFM before cutting into it. what vehicle do you have?
Last edited:
I've been tackling this issue further over the past weeks, and indeed have thrown parts at the problem. It has not gone away yet but helped me rule out certain variables. So far I tested my VAFM, coil, igniter, and distributor for correct voltage and ohms readings. VAFM and distributor checked out 10/10 times, they are reading out fine. Initially I got poor readings from my coil and igniter; I believe these to be the Denso originals from the factory in 89, both have the stickers and painted labels and are old looking. They both didn't pass the resistance testing, but upon replacement the new ones operated exactly as the first did though. This is most likely due to my poor job trying to understand the tseting procedures and making sure I get the correct readings, but neither coil or igniter is too far off what they should be. I'm thinking the originals really aren't bad as there are no other signs of damage on either, so once I know I have solved this issue I will likely throw them back in and get my money back on my non-Denso's as long as the originals still work.
As for my tests I ran on them, both sets of coil and igniter operated EXACTLY the same. After hooking up voltage reading on each of the coils, I get the same results. Once the car reaches operating temps there is a significant drop in voltage on the primary coil (the two outside lugs). I lose spark immediately. At temp on key turn there is enough juice for one singular spark from the coil to the distributor and after that the voltage drops from over 12 to 11, 10, and so on. Im assuming this really does rule out my igniter and coil, I want to assume if either one was malfunctioning I would not get the exact same results in the exact same ways like this.
I also sourced a Denso COR from rockauto so I will replace that anyways, if it fixes great, I somehow doubt it will do anything as my problem is not fuel supply related. Pump kicks on when I need it to for sure.
That means I have to go further down the line right? Is there going to be any sort of sensor that tells the engine to cut off my ignition once reaching a certain dangerous temperature? Coolant or O2 sensor? I have reason to believe all sensors and vacuum modules are originals from Toyota in 89, the truck has been somewhat neglected but nothing dangerous for the ECU as far as I know other than general wear and tear and heat. Fortunately everything was running typically before this issue came up so I would like to assume its a sensor failure or something simple like that. I can't be sure of the ECU as I have not tested it yet but I am willing to do all that for ignition cycles if I have to. Other than testing my ECU it could potentially be a short somewhere else. I did fortunately just rewrap my engine harness from the passenger fender to everything else (injectors, sensors, VAFM, and igniter) so I know their connections are solid. If it is a short it would be in the shorter length between that fender and the firewall.
Will be replacing my 80amp fuse as well as checking starter connections in the near future. Even though both work cold I want to rule them out with certainty.
As for my tests I ran on them, both sets of coil and igniter operated EXACTLY the same. After hooking up voltage reading on each of the coils, I get the same results. Once the car reaches operating temps there is a significant drop in voltage on the primary coil (the two outside lugs). I lose spark immediately. At temp on key turn there is enough juice for one singular spark from the coil to the distributor and after that the voltage drops from over 12 to 11, 10, and so on. Im assuming this really does rule out my igniter and coil, I want to assume if either one was malfunctioning I would not get the exact same results in the exact same ways like this.
I also sourced a Denso COR from rockauto so I will replace that anyways, if it fixes great, I somehow doubt it will do anything as my problem is not fuel supply related. Pump kicks on when I need it to for sure.
That means I have to go further down the line right? Is there going to be any sort of sensor that tells the engine to cut off my ignition once reaching a certain dangerous temperature? Coolant or O2 sensor? I have reason to believe all sensors and vacuum modules are originals from Toyota in 89, the truck has been somewhat neglected but nothing dangerous for the ECU as far as I know other than general wear and tear and heat. Fortunately everything was running typically before this issue came up so I would like to assume its a sensor failure or something simple like that. I can't be sure of the ECU as I have not tested it yet but I am willing to do all that for ignition cycles if I have to. Other than testing my ECU it could potentially be a short somewhere else. I did fortunately just rewrap my engine harness from the passenger fender to everything else (injectors, sensors, VAFM, and igniter) so I know their connections are solid. If it is a short it would be in the shorter length between that fender and the firewall.
Will be replacing my 80amp fuse as well as checking starter connections in the near future. Even though both work cold I want to rule them out with certainty.
I actually found a fix! Check your #1 injector connection. It’s exposed and more likely to wear and short out. Replaced mine and the car started right up.
Just replaced all my injector connectors, they are as good as new, I must have a short somewhere else :^/ Also rewrapped and replaced bad wiring for the whole engine harness from where it branches off the passenger fender and cleaned my injectors. I’ll check for other shorts soon.
I had issues with mine cutting out, not sure why but the tach would die for a second at a time when it was cutting out, only did it after driving like 10
Miles, found out loose pins in the air flow meter connector was the problem, how thats tied into the tach idk. Used a pick and made the pins less spread out and has worked fine since.
Miles, found out loose pins in the air flow meter connector was the problem, how thats tied into the tach idk. Used a pick and made the pins less spread out and has worked fine since.
Try driving with the fuel cap off. You never know it could be a tank breathing issue.
Hey I forgot I never updated this thread, turned out to be a bad distributor. Wasn't sending correct signals once going into the hot loop. I was only able to ifind out after getting myself a better multimeter with more functions. The one I got the truck with was not the original, something non-denso. Replaced it with the longest warrantied brand new replacement from oreillys and she runs like a champ. If people run into this problem in the future just dont rule out AFM connections being messed up. I did have a few internal solder joints broken that needed to be repaired along with the distributor. If you've soldered before it's not the worst job, just seal it back up with RTV once youre done.
Now I'm going for the head gasket which failed soon after replacing the distributor. Can't win em all.
Now I'm going for the head gasket which failed soon after replacing the distributor. Can't win em all.
