Running Rich (on Poor Man’s Income)

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I
Did you try to reset the ECU by pulling a battery terminal or ECU fuse for ~10-15 mins? Long term fuel trims may still be off?

Speaking of which, good to check for fuel trims before and after the reset and see if anything changes.
I did rest before. We also reset with the scanner today.

I don't know how to check the trims, but it sounded and ran the same etc, so probably close if not the same.
 
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Mine was doing exactly this a few years back. The culprit was the wire harness that runs by the top of the engine and a super hot exhaust pipe I think. It was getting almost melted, but Rewrapped it with some fire resistant wrap and has been good ever since. It’s an easy fix, would hurt to try it.
I did look at that, but rather quickly. I'll take another look at that area.

Thanks
 
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Mine was doing exactly this a few years back. The culprit was the wire harness that runs by the top of the engine and a super hot exhaust pipe I think. It was getting almost melted, but Rewrapped it with some fire resistant wrap and has been good ever since. It’s an easy fix, would hurt to try it.

you were getting intermittent issues, or specifically issues after it got hot?
 

bajaphile

Boojum Hugger
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So you got a misfire on cylinder 4, let's stick with trying to fix that code. I'd still check resistance of the spark plug wire, and even ensure the spark plug is getting a spark. Easy to check and rule out.

Still interesting that it happens after it warms up... That would mean that the ECU goes into the closed loop mode and starts utilizing sensors. There are apps out there that you can record live data in graph form. You might find something there.

For me, the most obvious culprit would be the injector.... Seems common on the 1FZ-FE that the injector wires running by the EGR pipe melt and ground out. I can't remember if that causes the injector to fail open or closed. Sounds like yours is failing open though...however, it would be failing regardless of engine temp....

I'd still take some time and inspect all the wires at that loom near EGR. Also, these same wires can be damaged behind the glove box as they pass nearby a sharp metallic edge. Try searching here, but I remember just taking off the glove box and they were right there. (I had a similar problem with mine several years ago where it was dumping fuel and wouldn't even idle at all...somehow I got lucky and just reset the ECU and never had the problem again).
 
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So you got a misfire on cylinder 4, let's stick with trying to fix that code. I'd still check resistance of the spark plug wire, and even ensure the spark plug is getting a spark. Easy to check and rule out.

Still interesting that it happens after it warms up... That would mean that the ECU goes into the closed loop mode and starts utilizing sensors. There are apps out there that you can record live data in graph form. You might find something there.

For me, the most obvious culprit would be the injector.... Seems common on the 1FZ-FE that the injector wires running by the EGR pipe melt and ground out. I can't remember if that causes the injector to fail open or closed. Sounds like yours is failing open though...however, it would be failing regardless of engine temp....

I'd still take some time and inspect all the wires at that loom near EGR. Also, these same wires can be damaged behind the glove box as they pass nearby a sharp metallic edge. Try searching here, but I remember just taking off the glove box and they were right there. (I had a similar problem with mine several years ago where it was dumping fuel and wouldn't even idle at all...somehow I got lucky and just reset the ECU and never had the problem again).
Thanks.
I‘m going to go ahead and do new cap, rotor, and plugs. (i’ve got the money and time and who knows what the future holds.)

The wire harness at the firewall looks kind of suspect, I will take a closer look at that this evening.

It definitely looks like the injector goes from good to dead for some reason at temperature.
 

Aloha Jen

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you were getting intermittent issues, or specifically issues after it got hot?
Once it heated up it would display the symptoms of the OP. Was fine at startup and idle. Once the wires were rewraped and reclipped above that exhaust pipe thing (egr or egt pipe??) it never had problems again.
 
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Update: NOT FIXED YET!!(see the end of this comment)
New:
O2s
Coolant temp sensor
Distributor cap
Rotor
6 new plugs
Ignition Coil
6 oem injectors
Full clean of all intake


Starts, idles down (about 600 rpm), purrs like a kitten....

I let it run at different rpm for 10 +minutes...all looked good.

THEN
A/C on idles at 800 rpm for 3 MINUTES removed or to 1500 when it idled back down it started misfiring.
 
Last edited:
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Ever heard of a noid light? It can help with diagnosis of injector firing or not. It may be that your injector on #4 is being told to stay energized constantly. On warm up this wouldn't be noticeable, but once it goes closed loop it can freak out the ecm as it tries to stay stoich.

Instead of a noid light you can use a mechanic's stethoscope or long screwdriver (handle end resting on your ear and tip lightly resting on or around each injector body) to verify opening and closing of the injector compared with known good injectors installed next to #4. If the injector doesn't make a rhythmic "ping ping ping" or "ting ting ting" or "tap tap tap" like the others, (hard to describe what the sound is but you'll understand once you hear it...hehe) you probably have a wiring issue. Sorry so long and hope this helps.
 
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Once it heated up it would display the symptoms of the OP. Was fine at startup and idle. Once the wires were rewraped and reclipped above that exhaust pipe thing (egr or egt pipe??) it never had problems again.
Ok good to know, I didn’t think that would be much of a possibility but that adds to a list of potential issues and troubleshooting for symptoms like that. Nice that is an easy fix in that scenario
 

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