I was asked to look at a Lexus ES330. The complaint was the car wouldn't go over 20MPH and would fall on it's face. The ECM was replaced and problem persisted. One coil was replaced around a year prior. Verified the complaint, car was hitting fuel cut and in limp mode.
Check Engine light is on with the codes:
Codes would set immediately after starting the engine.
Put a wire loop into the IGN fuse and captured a parade pattern.
Yellow: #6 IGT signal
Red: Ignition Coils, Primary Coils
It looks OK... I verified the secondary was firing with an adjustable spark tester.
Same capture zoomed out, you can observe the ECM stopping the injectors firing as it hits fuel cut.
So, on Toyota's/Lexus's the ECM sends the IGT signal to each coil and in return each coil returns an IGF signal to the PCM in a parade pattern.
I back probed terminal 24 on the E10 connector at the PCM and at the #6 IGF terminal.
As you can see the ignitor isn't sending back a good signal. Or it's just noise from the IGT signal/primary coil ramping and the ignitor is not sending back a signal at all.
IGF vs #6 IGT
So, the question. Why would all 6 coil ignitors fail at once? A power surge? A bad PCM driver? What would be a good test to determine the root cause of the failures?
I've heard tell of this happening, but have never run into this until now.