adb21

Hey everyone,
I'm new to the forum here, and have already found some great clues on this site to this headache of a problem on my '92 4x4 (22RE) that I recently bought. The previous owner had done all kinds of silly things that I've been unraveling, like putting in a mass airflow sensor from a V6 4runner, horrible wiring, etc.
Anyways, aside from rough running, the problem is this: After driving the truck for a couple weeks, it suddenly died while on the highway and wouldn't re-start. It has spark, has fuel. The cold injector fires, so it will run for a second or so, then die. The injectors are not getting the signal to fire, it seems.
I took it to a good toyota mechanic here, who said it would be alot of hours on his clock to check all the possibilities, but guessed it might be the wiring harness. My brother, a mechanic also (which I'm not much of), thought it was a bad ECM. We ended up finding a matching ECM at a salvage yard, popped it in, and bingo...it runs. Or ran. After running fine for a week or two, same thing. Died on the highway, then won't start; exactly the same symptoms: cold start injector fires, then nothing.
I found a post by Terrys87 on here that is very exciting, seeming that he might have had exactly the same issue, and solved it by shoring up the wires that splice from the ECM to the injectors. I'm going out as soon as I get the chance to check that out. But...seems weird that a new ECM would just make it fire right up, work for a week or two, then die again.
Any ideas, all you seasoned toyota techs? I and everyone I know is stumped. Hopefully it's those wires. I'll let y'all know. In the meantime, any ideas or experience around this issue would be greatly appreciated.

wyoming9

iTrader: (1)

You did check the first ECM was not working .

What codes were you able to pull up??

If the CEL was not lite you have poor connections in your harness.

This could be why the second one worked for awhile.

From the mess you have that was a engine harness you have your work cut out.

At least this way when it is all sorted out you will have a spare ECM

I can only Hope you can get your hands on The electrical wiring diagrams other wise you will be so frustrated .

adb21

Thanks for the response, wyoming. I'm diving into the wiring harness to see if I can find anything. Nothing yet. I am getting a check engine light, and the two engine codes I was getting are both related to the mass air flow sensor. We replaced that...it's from a '93 22re (my truck is a '92). I don't remember the exact codes.
I guess I'm just assuming that the ecms are bad, based on the fact that the car wouldn't run at all, then all the sudden ran fine upon replacing the ECM. Then it all quit again and won't run at all.
Is there a way to check whether the ecms are indeed bad? (I know I'm ignorant here...that's why I'm here.)

I appreciate your help.

YotaWoRx

What Is the part no. on the ECM u have? What is your vehicles VIN?

slow-mo

When you determined that it has fuel, did you check by testing fuel pressure?


You should first check to see if the computer is sending or not sending the command to the ejectors either with a noid light or even better, a graphing multimeter or automotive oscilloscope by back probing the connector harness. These fuel injectors pulse on and off in milliseconds, too fast for a regular multimeter.

The fuel injectors receive constant battery voltage on the power side of the connector and the computer switches the ground side to pulse (operate) the fuel injectors.

I'm not sure of the 22R-E's fuel injectors pulse pattern if they are turned on in pairs or all 4 at the same time. If they are done in pairs then two injectors will not be operating.

adb21

The ecm part # is 89661-35630
The vin is JT4RN13PXN6043854

YotaWoRx

Alright that is the correct computer for your year. Now check the circuit opening relay(powers fuel pump) and the ecu relay. Also bypass the circuit opening relay by jumping Fp and B+ in the diagnostic connector in the engine compartment using a paperclip. With the key on u should hear a small whine of the fuel pump running. If u don't you are steps closer to finding out what's up...

osv

the injectors are batch-fired, they all fire at once, the wiring in the harness has been patched to be different from what is on the schematic... the engine harness can corrode at that patch, and give all kinds of flakey errors.

you could pull the lid off of the ecu, and see if anything is burnt, or smells burnt... don't touch the connections on the circuit board if you can help it, it's good practice to be grounded before poking around on any kind of circuit board.

adb21

yes,
I've checked the fuel pump, it's working.

mitutoyo

Unless you have the time and patience messing with wiring diagrams, I would purchase a stock, unmolested harness and start from there.

adb21

That's what I'm thinking too. I'm going to check the local salvage yards for the wiring harness. Looks like only the 1992 4x4 will match. Any other ideas for where to find it online?

mitutoyo

I know some people trash talk Ebay but you can easily find it there. Just make sure that you find a seller with descent feedback and who can also promptly answer all of your questions. Most good sellers will usually take the time to help their customers prior to a sale.

Duffdog

It sounds like you might have the wrong impedance injectors on your truck. They make 2 kinds, high impedance and low impedance injectors. If your truck is supposed to have high impedance and someone installed low impedance injectors, the injectors will draw too much current and fry the ECU. This means that someone has also changed the injector connectors as well, that is how you know if they are the wrong type.

Could be worth checking out.

mitutoyo

1988 used low impedance 2-4ohm. 1989-95 used high impedance 11-14ohms. Simple multimeter test will rule this out.

adb21

I'm going to look for wiring harnesses in a nearby city at salvage yards. My understanding is that only the late 1991 and 1992 trucks will have that same ECM, thus the same harness, I assume. If I find harnesses that have already been pulled, if the plugs match up with the ECM, does that necessarily mean I have the right harness? Is there any other way to know for sure I am getting the correct harness for my ECM(89661-35630) at a salvage yard?
Thanks!