Pozi

Greetings,

Ok I think I may have this problem pegged but I wanted to run it by the masses to make sure I do not make a $400 mistake (more on that later).

I swapped in my 3.4L MT into my 1994 4Runner and finally came the day to start it. Before I go on any further let me just say what I have left to do: complete exhaust system (headers back), fill coolant and install air cleaner (intake installed with MAF sensor).

Now the engine, I am sure, is getting gas (smell) but only one of the coil packs are generating spark at any given time. Let me try to clarify. The #4 cylinder (front passenger cylinder) is the only to generate spark and likewise the cylinder at the other end of the wire, even when I rotate the coil packs.

My guess is that the ignitor has gone bad but spending $400 on an electrical part that can not be returned is .

Thanks for your input.

Also does anyone have an extra, working, ignitor that they want to sell?

midiwall

So... you rotate the coil packs and the problem stays with the cylinder pair? That's not a coil pack, that could be a shorted plug or plug wire grounding out the spark. Or a long shot could be the connection to the ECU or the ECU itself.

Do you have spark coming from the other two packs iin OTHER positions?

Pozi

I have spark in only one cylinder pair (#4 @ coil pack and at the other end of the plug wire) even when I rotate the coil packs. The plug wires are brand new out of the box.

midiwall

Okay, so the problem stays with the cylinder(s), and doesn't travel with the coil pack. That says that the coil packs are fine, and with the wires new, then they're probably fine.

Check that the ECU is actually trying to fire the coils on the other cylinders. You can do this by using a DMM to look for a voltage pulse at the connector on the coil. RED to the connector wire, BLACK to an _ENGINE_ ground. A DMM won't be fast enough to show you the actual voltage during crank, but any kind of reading is good. Since you know that #4 is "good", then do it there first so that you know what "good" will look like for the other connections.

You should try this first without the wire hooked to the coil pack.

My guess is that you will NOT have a pulse there. If you _DO_, then hook up the connector to the coil pack, put the pack onto the plug and run the wire to the sister cylinder. Check again for a pulse. If it's now gone, then you have a short - possibly (probably) in the plug itself.

If you don't see a pulse with the connector pulled, then check the connections to the ECU. Trace them with an ohm meter from where they tap to the ignitor all they way to the ECU itself. If you have continuity there, then since you don't have a pulse at the coil pack, then I would say that the ECU is flakey.

Was the 3.4 pull from a known working vehicle? Is the ECU that you're using the same one that was running with the engine before? Did the harness come with it?

Pozi

I was told that the ECU came from the same engine and yes the harness was on the engine when I got it. To compliment the engine harness I am using the ORS conversion harness.

midiwall

Hmmm.. I'm not familiar with how that may/may not impact the issue you're having. I just looked it up, but the ORS site is kinda' short on detailed info. Is that the harness that they mention here?
http://www.offroadsolutions.com/tech...uto.htm#wiring

It sounds like it may be a variable in this, but a continuity and pulse check should help figure things out.

Pozi

Yeah thats the one.

MTL_4runner

Holy cow, that may significantly complicate things. You might also try contacting ORS to help with diagnosis since they should be very familair with the ECU wiring any year to year changes with ECUs that might have different pinouts.

My bet is that your coils are all fine but if you want to check the test values are in this thread:
https://www.yotatech.com/forums/f2/3-4l-coil-pack-testing-acceptable-ranges-84527/

hektikwon

The year of your harness and ecu must match up. The Tacoma and 4runner also have different pins on their ecu for some years. I would recheck your parts. Check the voltage first though. If it ends up being an igniter problem I have an extra that I could sell you.

Pozi

pm'ed you