Can failing igniter not throw any codes?

[suprabee]

Yesterday I noticed a slight stumble when engine started several times during the day. I figured just an anomaly. Eventually at a start up, it did not start on first key turn. It would turn over but not start. I tried key again and it started. So I drove away about 500 feet to a stop light and then it stalled. Would not start after 3 key attempts. Opened hood, wiggled cps wiring. But nothing. I figured I needed a tow, so I pushed car backward 10 feet to get to a safer location. Tried it again and it started. Drove it home about 7 miles. It ran and idled fine at home, and started every time I shut it off for the next 45 minutes. I checked timing and was 10 tdc while in diagnostic mode. I fooled with and tried to get it to stall by bending the cps wires, coil pack harness, and wires out of igniter. Ran fine. Also. There were NO CODES. So, while running I pulled the larger connector on the igniter and of course it stalled and threw a code 14... which is what I expected to happen. I cleared the code and decided to install my spare known good and working igniter, and drove it this morning 50 miles to work no issues. The igniter I removed is the original one with 290k miles and I did the extra ground wire to chassis on it like 15 years ago. I also sprayed out the igniter and Coil pack harness connectors with electronic cleaner. I know there is a feedback loop between the igniter, coils and ecu, so I'm a little concerned that no code was thrown if indeed the igniter is failing. I was thinking fuel pump maybe as that is original as well, but I would think a fuel pump would cause a slow stall as pressure dropped. I had it just die. If it does it again I know how to trigger fuel pump, so can do that but any thoughts on my question about a failing igniter not throwing codes? Is that possible? Is it likely?

Why did I replace it? Well it's like 5 minutes to swap out and they way it stalled, then started a few minutes later made me think it might be going. Experience over the years tells me they can start to have issues, then usually get worse until they just fail completely (on other vehicles).

 

[suprabee]

One thing to mention, I did replace timing belt just last month, but had no issues with that, and it's been running fine since, and it was not my first timing belt on this car, so I've done it before.

 

[suprabee]

The CPS is also original that I "rebuilt" about 12 years ago when I installed a new bearing and higher temp seal on the shaft. And at that time I set the gaps to spec. And it's worked ever since. That was probably about 80 or 90k miles ago. I have no oil leaking from the CPS cover, but I have not opened it to peek inside.

 

[Nick M]

You might have wire deterioration just from the age of the vehicle. And you have an intermittent failure, and the older system doesn't really see it. I haven't thought about this in quite a while. IGf can only get a code if the command (IGt) to fire is given. When the leg of the transistor is activated, the IGf is part of that circuit and it is signaling that command was given.

Experience over the years tells me they can start to have issues, then usually get worse until they just fail completely (on other vehicles).

Yep. It might have a partial connection, inside the wire insulation. You might not be getting the signal, or it is interrupted from the ECM to the ignitor. If you don't get that signal, it won't set 14. I think. I attached the Toyota training from the early 90s on the ignition system (Electronic Spark Advance)