Hi all, I recently posted about one of the injectors going bad in my 1998 4Runner. However things have taken an interesting turn.

On the way to work last week, I decided to try pushing the little button on the shifter to lock it out of overdrive, just so it would at least not lug too badly on the way to work before I could get it fixed.

Within 5 minutes, the check engine light that had been on for days went out, and it was back to running like new, and continued to do so for the next 4 days, until yesterday, when I disengaged the OD lockout, at which time it started back with its dead miss.

So, I locked it out of OD again yesterday afternoon, and within 5 minutes, just like before, it was back to running perfectly.

So, I'm assuming I can scratch the injector and associated wiring off my bad checklist. Could a faulty ECU do something like this?

All assistance really appreciated!

That would be a new inference I hadn't read on here before. But hopefully not a bad ECU.

So the symptom is a CEL with related miss that seems to disappear/reappear based on the OD override button being in or out? That is wild but I suppose anything is possible. Never heard of it remotely here but again maybe a first?

So what's been 'tune-up' recently, wires/plugs, any new coils? How do they read? The symptoms you cite can be caused by a coil that is beginning to fail intermittetly. Just a thought. Luck and enjoy that runner.

I wouldn’t exactly blame the OD just yet. You have to think about the mechanics of what is happening to the injector when you use over drive and when you don’t. When you use overdrive it lowers the load engine rpm thus reducing the duty cycle (how much and how often the injector is spraying fuel). In the first 3 gears the engine is working usually always under load as you’re getting up to speed where it can shift to overdrive and take the load off the engine, meaning the injectors are always in their high duty cycle. My guess would just be that your injector is clogged or needs replacing. The check engine light comes on when it senses that the injector is not performing at optimal output, like when you’re in overdrive. But if you never get to overdrive the computer never notices that it’s not performing.

I could see the problem more clearly if the car only missed when it was actually operating in overdrive gear. The confusing thing here is that whenever the OD is engaged, the injector stops working completely, no matter what gear the car is in. It misses even at idle. Crazy.

So you have a dead skip driving and at idle in park and you are positive the fuel injector is the cause? The ECM can only identify an electrical problem with the injector circuit, it can't tell if the injector is plugged or leaking, etc. It can identify the misfire and maybe set a lean code. What are your codes? If just pushing the OD off button with the engine running in park makes the misfire go away it has to be a wiring or ECM problem unless when the overdrive is on it robs power from the injector circuit and shuts down a weak injector.

Can you post a Youtube video of you driving with it normally and then you touch the OD button and things light and CELs appear that were previously not there?
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Today I drove it with the OD locked out and it was back to missing. I still wonder what was responsible for that unusual change that lasted for days the first time I locked it out of OD and it ran great.

When the mechanic checked it last time, it was giving a #2 cylinder error, and when he put his stethoscope to the injector, it wasn't working. Time to just go ahead and replace the injector I guess.