Toyota missing injector/coil pulse

[Gareth]

dud coil me thinks

[pman92]

Exactly what I was thinking.
And turns out its on the money.

Was still playing up today so hooked the scope up to all 4 coil earths in the loom close to the coil, started it up and as soon as it played up the scope switched off. Obviously didn't like the voltage spike.
With a process of elimination worked out it still wouldn't idle steady and kept stalling with coils 1 2 or 4 disconnected.
But with coil 3 unplugged, it idled very steady and consistent despite the missfire.
Luckily have another vehicle in today with the same coils, so borrowed one, put it in number 3 and still good. As soon as I swapped the old number 3 coil back in, started playing up again. Swap them back and it's good. New coil is on the way.

Interesting thing is this coil still produces a very good spark. Jumps 30mm no worries, never misses a beat. Even keeps sparking consistently when it's causing the engine to run bad. Obviously it just induces a voltage back into the earth/control circuit that upsets everything else.
Part number of the coil is 90919-02243. Genuine Toyota. Probably the original one which is now 15 years old.

I've never seen one fail like this before. Has been a good learning experience

[pman92]

I was hoping to scope the coil primary current, and see how it showed up there.
But it turns out we haven't got an amp probe. Definitely be getting the boss man onto that and then hopefully I can check it out some day.

[Jayme]

thats what I like about some of the newer GM control systems... misfire detection.. on a mates Alloytec we had similar issue but we got the DTC misfire cyl 3. so we traded that coil for another cylinder and the misfire code moved to the new cylinder... bam problem sorted.

[VL400]

Newer Toyotas also have per cyl coil fail detection - got one last night on the rolla for cyl 1 Ran on 3 cyl until resetting the code, must have shut fuel off to that cylinder to save the cat. Runs fine today.... Will be labelling and swapping coils around, if it returns on another cyl its new COP time.

[Gareth]

I think the coil may have been leaking zaps out the sides (onto the plug tube walls) via shitty insulation, this issue is often caused by 'X' amount of heat cycles resulting brittlness, or oil leakage causing break down of the insulation. Are there any whiteish stains on the sides of the coil? Dont forget, a partially blocked injector resulting in a lean cylinder causes higher demand on the ignition system, another way only one cylinder is affected...

Glad you found the problem