Decided to play with the multi meter this morning on a whim and check for shorts in the igniter harness. I disconnected the ECU harness and the igniter harness. I left the coil packs connected but I may do this again with them disconnected. Im not sure if its normal but I did get some readings between various combination of wires at the igniter harness. This is my first time dealing with any electrical problems. Here is a picture of my results:

Update:

So I decided to do a little forum jumping to get some more opinions on this P1300 nightmare. So far they think my fugly soldering job messed up the connector possibly causing some sort of short where the connecter meets the igniter or perhaps extra resistance weakening the overall IGF signal to the ECM. I finally got my replacement connector in today after like 3weeks of waiting. I installed this morning in a quick and dirty twist tape method as I did not have time to break out the soldering iron. Needless to say it did not fix my problem. The new connector and wires are all reading 0.4 to 0.5 ohms between the igniter and ignition coils so I dont think there is a problem there.

This connector is so much nicer than mine. I think it came from a tacoma cuz the #10 wire is a different color.






I really wish I could find someone on this island with the same computer to swap out for testing.

Ive read through your post and clearly this has been very frustrating issue for you. It would be for any of us.
You have been throwing parts at the problem hoping for a solution but you haven’t troubleshot the issue properly. Ideally, you want to verify the issue 100% before buying parts. That being said, I have been in your shoes. I was trying to find out why my 22re wouldn’t start and bought a new igniter for $200 to find out my timing chain had snapped. These things happen.

I did some Google searching and see that you have replied to other people’s posts on this issue without much success. I would be interested in tracing some of those wires more to see if there are other issues. Find the pin out on the ECU and test with a DMM to verify all is good. I know you have done tests but they have seemed to change from being in and out of spec. That frayed wire and repair didn’t look good.
You could always leave a note on 4Runner you see around town and offer $20 if they let you test their igniter for 5 min. This might work, you never know.

Are there any igniter tests to perform?

Some additional thoughts on troubleshooting:

What is the status of the battery, current charge, when running what does it read?

Do you have an aftermarket alarm? Remote start? Any aftermarket lights or electricals?

It is possible a wire is heating up (high resistance), losing connectivity, or maybe shorting out

The FSM instructed me to check the voltage for the IGF pin on the ECU with the igniter discconected and the ignition in the "ON" position. If the voltage is between 4.5v and 5.5v, then replace the igniter. I was reading something like 4.98 volts. I replaced the igniter and we are still here.

The battery amazingly is still reading 12.51 volts when off. I have been disconnecting it when im not troubleshooting. I have probably started that engine 50 times since the beginning of this problem. Sometimes it runs for a few second or even a couple of minutes. I will definitely buy that brand of battery again. I have not checked the voltage when running.

The truck is completely stock. No alarms, no kill switches, even has the stock radio.

Trust me, I will if I see it again. Ive only seen 2 so far.

There no direct tests to perform that I can find. Its been more like "if this random part is working than replace this other unrelated component". I have attached the P1300 diagnostic procedure from my copy of the 2002 FSM. The ECM pin number are wrong and I found the right ones from another source but the procedure are the same. The only steps I have not done are the ones involving testing the IGT signals while cranking or steps that require an oscilloscope. Both steps basically end with replacing the ECM.

Attached Images

P1300 procedure.pdf (1.03 MB, 951 views)

@bentos1

Perhaps I should summarize what I have done up this point to consolidate some of the information.

In no particular order, I have done the following:

Parts replaced:
Igniter
Igniter connector
spark plugs
Plug wires
ignition coils

Tests performed:
Resistance check of the following:
Crankshaft position sensor --> Normal
Primary and secondary for the old coil packs --> Normal

Voltage check:
Igniter power supply wire --> within Normal range
IGF pin of the ECM --> Normal Range
Battery --> 12.51 volts as of yesterday

Continuity Check with the meter set to make noise:
3 wires from the igniter to the coil packs
3 wires for the IGT signal between igniter and ECM
1 wire for the IGF signal beween the igniter and ECM
1 ground wire --> good at the ground point and the battery
1 common power wire --> voltage check
1 wire for the Tacometer --> not tested

Wire short check at the igniter connector:
I checked all 10 wires against themselves to check for shorts but I think I did it wrong
since I left the coil connected. Looking at the wiring diagram there are couple of wires that
should be able to "talk" to each other such as through the ground or common power wire. I
might do it again later. Still new to using the meter, I might be using it incorrectly. I posted a
graphic showing my results but like I said, I thinks it was performed incorrectly.

Lastly I have located every ground possible and sanded the paint down to metal ensuring a
fantastic ground.

Maybe fuel pressure could be the issue? Fuel pump wiring/ground? Saw that was an issue with another person.

You mentioned pulling on wires before and that lead you to the break in the wire. Maybe just start pulling at everything?

It might be worth pulling the ECU and checking the board and looking for bad traces, or blown parts. I have seen people post those things before.

Sorry man, I am just trying to think of idea's. I have never had this issue before and I know how frustrating tracking down a gremlin like this can be.

http://tacoma.site40.net/4Runner_96-.../ignsy/ovi.pdf

full manual: http://tacoma.site40.net/4Runner_96-...g/contents.htm

Honestly at this point I think its the computer but they are so damn expensive that Im hesitating buying one. I also cant prove it without expensive tools. There seem to be a lot of ECMs available on the car-parts.com site. I have emailed several of them and none of them will reply to my messages. Make calls from here is expensive and a hassle with lots of static and frequent dropped calls.

Turned out to be the MAF for this guy: 3.4 Sudden Quit - RockSolidToys Toyota Solid Axle Swap & 4X4 Forum Facebook
Test/Clean your MAF. Should not take long to do.

Other stated it was wiring @ the connector like you had before.

One guy had a bad fuel pump ground. Jump your fuel pump maybe?

Open up the ECU and send a large pic. Both sides. We can look @ the board for anything obvious.
ECU's do fail but not often. I would keep working with you have until you can verify the issue through more troubleshooting. The CEL code triggers p1300 but it doesn't mean that is what is causing the issue itself.

Thank for the suggestion. I did read through that thread and I actually cleaned the MAF a few weeks before the P1300 due to a code for the MAF it was throwing. I dont remember the code though. I will try and remove the ECM later today or early tomorrow depending on how my schedule works out today.

Remember what I said about the codes. Just because a code points to one part of the vehicle, that doesn't mean the problem lies there. The computer is throwing the problem it can see but it might lie elsewhere.

Keep us updated. You can get this fixed!!!

Hey man, I appreciate the updates. Keep at it.


Sent from my iPhone using Tapatalk

Update:

Ok guys, I was able to remove the ECM and i almost stripped 1 of the damn screws. I could believe how stuck it was. Anyways, I took several photos of the board on both sides. I am going to try and post large photos so you guys can review them easier. I would like to embed them but I think i will post links to my dropbox photos so at least the links can stay here. I hate when 3rd party hosted photos vanish. It really negatively impacts people years down the road looking for the same information.

Back
https://www.dropbox.com/s/msbhon7qce...92612.jpg?dl=0
https://www.dropbox.com/s/47ydujyxuz...92714.jpg?dl=0

Front
https://www.dropbox.com/s/lq0w4jwezo...92803.jpg?dl=0
https://www.dropbox.com/s/a3bxkeyudt...92807.jpg?dl=0

Suspect area on front side
https://www.dropbox.com/s/bgmzih896n...92912.jpg?dl=0
https://www.dropbox.com/s/9vodd8mnyy...92937.jpg?dl=0

If Im not mistaken, that looks like the entrails of capacitor that leaked onto the board.
What do you more circuitry inclined people think?

Also I removed my MAF and tried to check the resistence but I dont know which pins to check. Here is a picture.

Those are great pics of the ECM. That area you mentioned looks pretty crubulated. You could try cleaning the board with alcohol but something happened in that area You could look at a schematic to find out what that area does, but even then it would super complicated.

Here is the MAF troubleshooting:
http://tacoma.site40.net/4Runner_96-...fe/cip0100.pdf
http://tacoma.site40.net/4Runner_96-...fe/cip0101.pdf

Check your area for a 4runner for sale and offer $25 to borrow their ECU for 5 min. Maybe you could determine if that was part of the issue. Those crusty bits don't look so great. I wouldn't want to suggest replacing it unless it does turn out to be that part, they are expensive. Maybe a member here has a spare ECU that you could use for testing?

ECM pinout:
http://tacoma.site40.net/4Runner_96-...zfe/terecm.pdf

Let us know the results of your MAF testing.

I'd say you have it right on that cap.

As to the MAF, you can see the pin-outs for the '96 5VZ-FE MAF in the attached. However, I don't have the resistance specs for the early MAF type. Since they are interchangeable with the later one, I'll go out on a limb and link those.

http://tacoma.site40.net/4Runner_96-.../mafm/insp.pdf

The MAF is shown on the '96 EWD and the wire labels and pin numbers are given on the MAF box. Then to see the pin-out, go to the bottom and look at the diagram for plug M1.

Attached Images

Engine Control 5VZFE.pdf (151.7 KB, 197 views)

I wouldnt even know where to start looking for that ECM schematic. Your diagram of the ECU is a newer version for like the 2002 model. It has 5 sections, my 96 only has 4 sections of the ECM. The ignition signals arent any where near that area but who really knows where those signals travel once inside the ECM.....

I did find an interesting thread about a guy who replaces capacitors on 90s model Lexus ECMs.
All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor) - Club Lexus Forums

I have soldered a thing or 2 on PCB boards before. I would definitely be willing to try replacing the affected capacitors