First car, lx450!

[tug123]

With #6 unplugged you are running on 5 cylinders which will be rough and shake around more than usual. That residual fuel will eventually burn off once you get the situation for injector #6 resolved and it's not dumping a ton of fuel from staying open all of the time. I doubt that part of the exhaust manifold has a chance to really warm up since it's being cooled by the massive amount of raw fuel going into it, especially unloaded (idling not driving).

Next steps would be sorting out the wiring issue, confirming its running smoothly, burn off the residual fuel, and then once you confirm its running and driving as it should change the oil since it may be diluted with fuel. If the coolant level has not changed that's a good sign the head gasket is ok.

Sounds good, makes sense to me, it definitely isn't getting that hot for sure, I don't run it for more than a few minutes really ever.

Already ordered a wiring harness, will do an injector swap in the next few days just to double check that all injectors are OK. I really don't think there is a HG problem, no signs point to it except the smoke. Seems like this is a far simpler solution than I was expecting.

 

[ZackR]

Now that you have practice pulling the upper intake the wiring harness shouldn't be too difficult. Glad to see light at the end of the tunnel on this one.

 

[60 toy ota]

change the oil since it may be diluted with fuel.

DEFINITELY.

Your injectors have constant power with key on, and each injector individually grounds out at the ecu. I'm betting the #6 injector is shorting out on the ground side. pull the connector of the ECU which houses the #6 injector ground side, as well as #6 unplugged at the injector. do a continuity test between the #6 injector ground pin on the harness connector (either at ECU or injector) and ground. from your symptoms I'm betting there will be continuity or intermittent continuity (move the harness near EGR around to verify). If there is, that's your smoking gun and you need to find the short.

 

[tug123]

DEFINITELY.

Your injectors have constant power with key on, and each injector individually grounds out at the ecu. I'm betting the #6 injector is shorting out on the ground side. pull the connector of the ECU which houses the #6 injector ground side, as well as #6 unplugged at the injector. do a continuity test between the #6 injector ground pin on the harness connector (either at ECU or injector) and ground. from your symptoms I'm betting there will be continuity or intermittent continuity (move the harness near EGR around to verify). If there is, that's your smoking gun and you need to find the short.

Never heard of this before, but this seems like what I was looking for a few weeks ago for a more in depth test.

So basically on no power, test the resistance between ground/injector #6 (or on ECU) and make sure that it goes to zero? If not, I'm seeing a short?

 

[ZackR]

Think of it this way, the injector has 12V applied (constant power) when the ignition is on. The ECU is the switch that is allowing the circuit to be open or closed, it's just on the ground side instead of the power side. It's like disconnecting your negative battery cable instead of the positive cable. Either will terminate the circuit.

I did a quick scan of the EWD (engine wiring diagram) and this should be accurate but you'll need to double check. Injector #6 is highlighted with a blue circle. Power is coming from the B-R wire when the key is on and if you follow the Y-L wire ( #6 injector ground) to the ECU you can see where it's connected to the ECU.

Per @60 toy ota 's note you want to disconnect the wiring harness where it attaches to the ECU and disconnect the wire to the #6 injector. Set your multimeter to continuity (ohms) and put one of the leads into either end of the Y-L wire. Attach the other lead to a good ground and see if you have continuity (there shouldn't be if things were working normally but I bet yours is). If there is no continuity shake the wiring harness around and see if its intermittent.

This test will tell you if the #6 injector ground wire is shorting to ground even when the ECU is not asking it to, hence it begin switched on and allowing uncontrolled fuel out of the injector. Finding where this wire is shorted is a bigger project and will require you to remove and open the wiring harness.

 

[60 toy ota]

Well put, @ZackR

So basically on no power, test the resistance between ground/injector #6 (or on ECU) and make sure that it goes to zero? If not, I'm seeing a short?

Not quite. Zero resistance means 100% continuity, so if it goes to zero you are seeing a short. With the multimeter set to Ohms, you should se something like "o.L" (or another indication of an open circuit) on a properly functioning harness. some multimeters have a continuity mode that will beep to show no resistance/continuity. If yours has that the symbol will look like a diode (kinda looks like the fast forward symbol).

 

[tug123]

Think of it this way, the injector has 12V applied (constant power) when the ignition is on. The ECU is the switch that is allowing the circuit to be open or closed, it's just on the ground side instead of the power side. It's like disconnecting your negative battery cable instead of the positive cable. Either will terminate the circuit.

I did a quick scan of the EWD (engine wiring diagram) and this should be accurate but you'll need to double check. Injector #6 is highlighted with a blue circle. Power is coming from the B-R wire when the key is on and if you follow the Y-L wire ( #6 injector ground) to the ECU you can see where it's connected to the ECU.

Per @60 toy ota 's note you want to disconnect the wiring harness where it attaches to the ECU and disconnect the wire to the #6 injector. Set your multimeter to continuity (ohms) and put one of the leads into either end of the Y-L wire. Attach the other lead to a good ground and see if you have continuity (there shouldn't be if things were working normally but I bet yours is). If there is no continuity shake the wiring harness around and see if its intermittent.

This test will tell you if the #6 injector ground wire is shorting to ground even when the ECU is not asking it to, hence it begin switched on and allowing uncontrolled fuel out of the injector. Finding where this wire is shorted is a bigger project and will require you to remove and open the wiring harness.

View attachment 3692191
View attachment 3692193

Well put, @ZackR

Not quite. Zero resistance means 100% continuity, so if it goes to zero you are seeing a short. With the multimeter set to Ohms, you should se something like "o.L" (or another indication of an open circuit) on a properly functioning harness. some multimeters have a continuity mode that will beep to show no resistance/continuity. If yours has that the symbol will look like a diode (kinda looks like the fast forward symbol).

Thank you to both of you! This is way more in depth than I was expecting, but learned a lot troubleshooting this one. That ECU is not fun to disconnect.

There absolutely was continuity, but it was intermittent for sure. This makes me feel better that at least I have proof of why the #6 misfire is happening instead of just guessing.

New wiring harness arrives next week, will pull the old on, swap it, and hopefully it should just be fluid changes after that.

 

[tug123]

I got a good bit of the wiring harness unplugged (intake off already). All injectors and everything up top, and all the knock sensors and what not up to the starter (got the starter stuff unplugged as well though). I don't have the new wiring harness on hand yet, so it's hard to tell, but it seems like past the starter there are two plugs covered in foam + some long skinny line that goes along the transmission pretty far back? I haven't pulled the starter yet, maybe that's why everyone says to pull it, for these remaining ones?

 

[tug123]

I think I answered my own question - seems those "foam connectors" are the connectors that go to the transmission harness, so unplug those. The long skinny line I was looking at was the transmission harness, what I should be looking for is the one that drapes over to the passenger side. I *think this is accurate.

*Edit: best way to find the line over the transmission is to start at the O2 sensors and follow them back. It's pretty clear where it goes over on one side by the starter and out on the other to the O2 sensors.

 

[tug123]

Anyone know how to open one of the connectors (EC1) going to the transmission harness (PN 90980-11087)? EC2 was easy, just press, but no amount of pressing makes this thing move. Tried pulling up with a pick, still nothing, really at a loss here. Want to just cut it but then I still have to get it off to put the new harness on.

 

[whiteyota]

Is this one of the foam covered ones behind the starter?
I just did mine last week, I pulled the harness toward the outside and twisted it so the tab was facing out.
I couldnt get the tab to depress with my fingers so took a straight slot screwdriver and gently applied pressure across the tab,then wiggled the both sides of the connection.
It took a bit of work,but eventually it let go.

 

[tug123]

Is this one of the foam covered ones behind the starter?
I just did mine last week, I pulled the harness toward the outside and twisted it so the tab was facing out.
I couldnt get the tab to depress with my fingers so took a straight slot screwdriver and gently applied pressure across the tab,then wiggled the both sides of the connection.
It took a bit of work,but eventually it let go.

Yep that's the one - I'll go at it again later today, I wasn't putting much pressure at all in case it was the wrong way to pull it, but that makes sense.

 

[tug123]

Got that connector, hope this is the last thing - how am I supposed to cut this zip tie? This is above the transmission, closer to the driver's side but fairly hard to tell. Can barely slip my hand in to touch it through the side of the transmission, but sticking a knife up there seems like a horrible idea. This is a picture of my borescope so quality isn't great.

 

[banjo1981]

Maybe long needle nose and twist. It’s probably pretty brittle. Good job so far

 

[tug123]

Maybe long needle nose and twist. It’s probably pretty brittle. Good job so far

Fair enough, will go at it again tomorrow. There's absolutely no way people are somehow re-ziptying this after they replace the harness, right? Would be a miracle if you could.

 

[whiteyota]

I think that zip tie is anchored to the top of the trans.
Lemme go look at my harness, I will post a pic.

 

[whiteyota]

No zip tie on my old one, I would use a pair of dykes to get in there and clip it off

 

[tug123]

Finally got it out! Just grabbed needle nose, nothing else would fit, and as banjo said it came right apart. After that was pretty straightforward. New harness should arrive today.

 

[banjo1981]

Nice job! Hoping this gets you on the road finally enjoying your cruiser. It really is a good feeling when you get one running well.

 

[sbman]

Did you verify with a continuity meter that the harness was the issue? I've been down this road before (post #66) and it turned out to be a bad injector. I could not find a short in the harness so the injector was the only remaining possibility. Cleaning them does not guarantee they will perform correctly if they are mechanically worn out.