Lanqe

Yeah I'm stumped

Lanqe

Bump.

Any wiring wizards. For the ignition side?

Terrys87

iTrader: (1)

I would like to see some explaining of the Ignition Side as well.

jennygirl

Did you check for spark yet? Scope had a great suggestion with the timing gun.

Also wanted to thank Terry for the clue about coil resistance. I checked mine and it was 0.1ohm.. Then found out PO had installed an aftermarket coil. I went to the junkyard and they gave me a Toyota one for free. The difference is noticeable and car runs smoother Getting closer to laying my idle misfire to rest!

Thanks Terry

RJR

You need to test the connectivity between the ignitor and the ECU with an ohm meter, specifically the IGF line. It doesn't matter how healthy the ignitor is, if the signal doesn't get back to the ECU it won't run.

This manual page http://personal.utulsa.edu/~nathan-b...ne/44engin.pdf will give you the pinout of the ECU. You're looking for the pin labeled IGT.

This manual page http://personal.utulsa.edu/~nathan-b.../2systemci.pdf shows the overall ignition diagram. Unfortunately, I can't find a connector diagram for the coil/ignitor, but there are only a few signals to ohm out, so you should be able to find one that connects to IGF on the ECU. If you can't find any, then that's a problem.

The IGF signal also appears on the diagnostic connector on later models - not sure about yours.

I found a diagram of the ignitor connections - attached - RJR

falcon4runner

Well my 89 4runner is doing the same thing. I got the ECU wet over the weekend and I can get it to start and run for about 2 seconds and then it dies. I checked everything in the harness and the igniter and coil. I jumped the cold start injector and got it to run longer...so I certainly have a problem with my injectors not getting the signal to open. I am getting another ECU and I hope that fixes my problem.
So maybe you should open up your ECU and check to see if it is good.

Terrys87

iTrader: (1)

falcon4runner.. The only time I have seen a ECU fail is when it gets wet. From my experience, it is a solid piece of equipment. I would bet another ECU and you will be good to go on that.

RJR...This might be a dumb question, I had a truck that I could not get power to the coil. Just for trouble shooting purposes only, could you run a temporary wire straight from the battery positive to the coil positive and do the same with the negative? Reason I ask is I had a similar problem one time but it was due to no power. In this way you could cut the problem from the coil/igniter to the plugs or from the coil/igniter back to the battery.

The truck I had this issue with, the harness was so hacked up, that I just swapped it out. I knew the coil to the plugs were good, but it would be a quick check if it is possible to do something like that.

falcon4runner

Terrys87 I would certainly tend to agree with you.
I went back and re read the original post. If the truck was running fine before the bumpy road then it had to be something that came loose. I remember on my brother's 87 runner the AMF got unplugged and we had the same thing happen. But that is a more obvious fix.
As I'm sure everyone knows here in AZ, our wiring gets crispy because of the heat. Connectors break and so do wires. Lanqe, I think you should do a resistance check at the ECU. It is outlined in the fsm. It will basically tell you if your ECU is getting everything that it needs from the harness. From there you should be able to tell if your harness is good. It's really the only other thing besides a bad ECU that I can think of.

RJR

You can connect +12V from the battery to the top of the coil, but you can't just connect ground to the low side - you'll probably burn it out that way. Continuous current will overheat it. The coil is designed for pulsed operation. It gets a continuous +12V from the battery (through the ignition switch and fuse, etc.), and then the ignitor pulses the low side to ground to create the high voltage spark from the coil. The timing signals from the distributor and the ECU tell the ignitor when to pulse the coil.

The current from the coil goes through the ignitor to ground through the ignitor frame, so you need to make sure the ignitor is bolted down good to a solid part of the vehicle frame, and make sure the bolt connections are clean and corrosion free.

Falcon4runner makes a good point, in that so often we focus on the sensors, and forget that the harness is crucial as well. A perfect sensor does the ECU no good if the signal doesn't make it through the wiring, and with our old trucks, let's face it, the wiring and connectors aren't what they were when it rolled off the factory floor.

jennygirl

I was putting my car back together tonight after installing a new fuel pressure regulator and left the AFM connector off. This exact same thing happened... Car only stayed running for a few seconds.

Make sure you are getting a good signal from the AFM to ECU. For quick ref




The ECU has to see AFM flapper open signal (Vs) in order to keep the fuel pump active, and it also needs to send voltage through Vb for that to happen.. What may check out at the sensor source (AFM) might not be checking out at the ECU- as RJR suggested. I would try continuity checks on all of these connections from AFM<->ECU.

Edit: Oops I meant Fc and E1 for the fuel pump.

mikekfr

Just throwing this out there, if the engine coolant temp sensor went bad, could it be sending failed info to cause your symptoms? It's not a very expensive item and by my experience, it WILL shut everything down like a boss.

When i had this sensor fail, i had sudden no start, rough idle when forced to start, and black smoke, all happening at the drop of a hat. Sensor was $20.

Good luck

falcon4runner

Well I put another ECU in my truck and I get the same cranks and no start. So I have the same problem as you do. I have a new battery, starter (my old ones were killed), swapped out 2 new ECUs, EFI relays, and Circuit Opening Relays. I also changed out the fuel filter since I had the starter out.

I did resistance checks at the ECU. I checked for fuel (cracked the line at the tank, cracked the cold start, and jumped the engine temp sensor, and fuel pump). I checked spark (pulled a wire and put another plug and grounded it to see if there was spark). I also checked air (amf door was opening while cranking and if you open the amf door, the fuel pump truns on).

I have read just about every forum posting with others that have this issue.
I will be checking the injectors with a noid light, I will also check the fuel pressure again at the rail. I am also thinking about swapping out the fuel pump.

If and when I figure this out, I will let you know because I'm starting to have a sneaking suspicion that we are having similar issues.

In the meantime, any other ideas?... for me, all of this was because I got the ecu wet while wheeling (but it was pretty brutal recovering the truck). Has not stayed running since. Cranks, starts, runs for 2 seconds, dead. I will try and post a pic of it in the water.

falcon4runner

Not the best pic, but you can see the passenger side is in the water. Truck was at an angle

RJR

Are you gettting any CEL codes?

falcon4runner

IIRC was getting a code 14 (no NE signal to ECU) but that was only with one of the ECUs. That ECU was a later part number for a 91 that I had laying around. I get nothing with the two correct part number ECUs. After 89.5, I believe there is another ignition control module which may have been the cause of that CEL.

RJR

I'm not sure how yours would operate. The later models will shut off the injectors if the ECU doesn't get an IGF signal back from the igniter, and throw a diag code 14. Your next step of putting a noid light on the injectors should be instructive.

falcon4runner

So I did everything in the above post. Noid lights came on and flashed, so we checked out the distributor again as well as the coil and that was all good. So we checked fuel pressure...and that was good.

So. After almost giving up, we took a sample of gas. It looked bad, like there was no gas...just water. In fact, it was all water. It barely caught fire. Took a sample of known good gas to compare, and it was very different looking, not to mention combustible.

Wow... so I drained the tank and there was a heck of a lot of water in there. Gonna get some Heet and some good 91 octane gas and see what happens.

Just thought I would share...

Lanqe

Sorry for such the late reply but i finally got it running.. after cutting the entire harness apart haha I thought I would jump and and summarize everything up just for future readers

So after swapping out and testing basically every part I figured it was between he fuel filter and injectors or the wiring somewhere in the harness. Weird thing was, all my wiring tested out fine on the DMM. So i pull the intake fuel rail ect. and go looking for a clog with my fingers crossed. but nothing. Injectors tested out perfect and everything seemed to be ok. So my only option was splitting open the harness in which i discovered a couple loose connections. What was weird is none of the connections seemed to be bad enough to keep it from running but i decided to fix them good while i was in there. Turned out that was the problem.

So i just want to say a big THANK YOU to everyone that helped me!

Odin

Wow, this thread has a pretty good amount of info. Gunna bookmark this sucker!