S14 SR20DET Weird Misfire/Idle after Warm only when revved past 3k

[grizzly8181]

Having an issue with an s13 redtop in an s14
Car runs perfectly fine while it is cold and warming up however after about 15 minutes of driving it will do this
Once car is warmed up if i rev it above 3k and then it?ll want to die when it comes down and won?t let me accelerate almost like it?s in limp mode, unplugging cylinder 1 returns it back to normal and it runs perfectly fine, if I rev above 3k again it does the same thing

Issue started randomly one day on the freeway, it just backfired super loud and bogged down like that

Video showing issue

https://youtu.be/NOqH37UZpj8

[S14rebuild]

Check coil packs, ignitor

[grizzly8181]

Check coil packs, ignitor

Did some more testing today whenever this is occuring only cylinder 4 is sparking. 3,2,1 are no longer sparking. So the engine is only running on cylinder 4. This cutout typically happens during higher rpm like past 3k itll just suddenly cut out and start running on cylinder 4. I can wait a while to restart the car and itll run fine on all 4 again. This cutout will only happen after the car has ran for a bit, when it is cold i can rev it to anything and it will be fine.
Is this pointing to a bad ignitor? Or bad ecu?

[NukeKS14]

Or wiring. Check your coil pack harness. Pull it and inspect everything. Could be some insulation rubbed off/nicked and is shorting out.

[grizzly8181]

Or wiring. Check your coil pack harness. Pull it and inspect everything. Could be some insulation rubbed off/nicked and is shorting out.

If it were more wiring related though wouldn?t it be doing it all the time instead of only after the car runs for a while? On cold starts I can rev it to anything and it never does this but drive around for 5-10 minutes and any high rev will cause it to only fire on cylinder 4. I’m going to check the signal from the ecu and igniter to make sure that is still going through.

[NukeKS14]

If it were more wiring related though wouldn?t it be doing it all the time instead of only after the car runs for a while?.

Not necessarily. If its nicked or making incidental contact when it gets jostled from the engine moving it wont be all of the time. Just something easy to check and rule out. I had a similar issue from my coil pack harness grounding out intermittently from a small nick on the timing loop.

[grizzly8181]

Not necessarily. If its nicked or making incidental contact when it gets jostled from the engine moving it wont be all of the time. Just something easy to check and rule out. I had a similar issue from my coil pack harness grounding out intermittently from a small nick on the timing loop.

Solved the issue! Ignitor was bad, got it replaced and it?s all good now