You need to know how the igniter works. There are two signals as you know IGT and IGF.
Do you know how those work and how do you confirm those?

Without confirmations, you can't troubleshoot quickly and well.

 

Ne = Engine speed sensor
G1 = #1 Cam position sensor
G2 = #2 Cam position sensor

Ignition timing is determined by the ECU based on signals from sensors G1, G2, Ne.
When it is determined the ECU sends an IGt signal to the igniter at a predetermined timing (30 crankshaft angle) before ignition. The transistor inside the igniter is turned on by this signal and primary current is supplied from the ignition switch to the coil. When the crank reaches ignition timing point, the ECU stops supplying the IGT signal. The transistor inside the igniter is turned off and the primary current to the ignition coil is cut off as a result. At this time the secondary voltage is induced in the coil. The secondary voltage is what goes from the coil to the distributor s and to the spark plugs. The counter EMF that is generated when the primary current is cut off causes an ignition confirmation signal IGf, which is sent to the igniter.

Okay Yamae do I get an A+ ? At least I know the basics here, right ?

So what happens if we loose one of the IGf signals? There are 2 of them since there are 2 igniters does loss of one cause shut down? I'll have to study it.

 

You do fairly a good job, dicer, explaining how the ignition works. But sorry to say that I can't give you "A+" because you made a major mistake at the important final part. Are you sure that the IGF is sent to the igniter?

Can you correct it? Then I can give you "A" but still not "A+" because there is one more minor mistake in your post writing about the turn off timing. Sorry that as an Japanese EE, may be I am a bit too strict. But that's the way us Japanese engineers always do things. Without the strictness, we would be the same with those who live in the counties near by. Japan is a country where no natural resources are there. Without efforts and hard workings, we have no idea to survive.

Other than your explanation, the fire timing is adjusted precisely by different factors such as the load, the temperature of intake air, the temperature of the cooling water, the engine rpm and a few others. If you'd explain these and above major and minor mistake are corrected, you'd get "A++".

 

I'll study the IGf better, the last things you mentioned are covered by the ECU that I mentioned and that is the main control over all things that are controlled by it. It does say ignition point and like you say that is going to be varied by the ECU according those inputs (variables) that you mentioned.
I like you Yamae, you make me think and study more. Japanese are some of the best engineers, some of the best machine tools are from Japan as well as heavy equipment and precision measuring tools, cars and trucks, all quality stuff.

 

You guys are great!

Dicer, Yamae was highlighting what I think was just really a typo on your part. The ignition confirmation signal, IGF, is a signal sent to (an input to) the ECU.....not the igniter.

For the coils, they are transformers essentially. So there is fundamentally no delay between timing of the supply of input voltage (from the igniter) and the output voltage (to the distributor.) So once the IGT signal is gone, the voltage to the distributor is also gone.

I have to travel today, so it might be a couple days before I get back on the old gal. I'll be away from the car as well.

Thank you both.

 

Your right ECU.

 

Well, spent a little more time this weekend and I think she's back to normal, but unfortunately, I don't exactly know why.

1. I seperated each electrical plug from the harness to the cam position sensors and checked resistance on each. 1200 ohms warm.....1400 ohms hot. So that's in the acceptable range. I plugged them back together and since that point, no more hot engine start failures.

So ah, uh, hmmm, what happened?

Only thing I can think of is that the drivers side cam position sensor was replaced by dealer about 6 weeks ago or so. This problem started occuring after that visit. Is it possible that when the dealer was reworking that connector (getting the new cam position sensor wiring connected into the factory connector) that something wasn't quite right and made it suseptable to heat and when I unplugged and then re-plugged that connector it "fixed" the issue. I think not, really, but after I messed around with those connectors, the problem did not reappear.

An unsatisfying end to the hunt for this problem....mainly because I didn't find anything 100% conclusive and I'm not sure the problem will not reappear.

If I find anything else out of interest, I'll post back.

 

That sometimes does the fix, a skin of corrosion on the connector plugs and just movement reestablishes contact, same goes for fuses.

 

SOLVED.

Well, the problem did reappear and I started a new thread on it because it didn't seem to be related to the crank position sensor itself. However, it did end up being associated with the wiring further into the harness. See below.

Oh my, this was challenging. The last thing that I did was to swap out igniters one at a time with a replacement. That didn't make any difference. That was pretty much the last item for me to check. I also check the main relays (fuel pump, cut out, EFI) and they all checked out.

I even started to look at the fuel pump / fuel system / fuel pump resistor, but it all looked OK and checked out. One note for future readers, the fuel pump on this car is very, very quiet. Unless I got into the trunk, or took the back seat back out, it was difficult to hear. So when you are sitting in the drivers seat and you don't hear the pump running, don't make the assumption that it isn't.

Anyway, when I was out of ideas, I began to gently push and prod on all the electrical connectors and wiring harness in the engine bay. When I pushed in the area of the wiring connectors near the furthest front drivers side fuel injector the engine would die. This was repeatable...finally, I was onto something!! There are three connectors in that area. One is the fuel injector connector, one is a two wire connector, and one a six wire connector. When I pushed on the six wire connector the engine would die. The wires were packed pretty tight in this area and it also appears someone had taken off the six wire connector in the past and it seemed to be twisted 360 degrees from optium which made the wires a little twisted and strained. When I looked closely at the wiring, it appeared that one of the wires was maybe getting pinched against some of the sharper aluminum edge of the block (near the valve cover). So I'm thinking as the engine became warm after a heat soak, that had an influence on the wire. Guess which wire this was? Crank position sensor.

I gave the wiring in this area more room and removed stress and I can no longer repeat the problem.

Lesson learned - if you have an intermittent electrical problem, push and gently pull on all the engine bay wiring and connectors and see if you can cause your problem. It might just be a physical wiring or connector problem.

Thanks to everyone, especially Yamae & Dicer in trying to help with this problem.

 

And thanks for letting us know what you found. And good find, not a normal problem, so I wonder if it was an area that would short to the sharp corner or is the wire bad there and would separate and lose the connection? If its the last it could reappear at a later date. Its not good to twist up wire connectors and or route over a sharp or hot part, always route and clamp the wires like the factory did it.

 

Another thanks for letting us know what the problem was. I had a similar problem on a Harley that took me almost a year to figure out.

 

Thanks for reporting the detail. This sure would help others in the future.