Turns over, no start, no spark, no dtc’s

2006 Subaru Baja sport, 2.5L normally aspirated.

The issue with the vehicle was that it stalled intermittently. It would restart and I could continue driving. This started shortly after the CEL came on.

Things I have done since are as follows:

Had a no spark condition, replaced coil pack. Vehicle started and headed home. It broke down again with the same issue after 12 miles. I put the old coil back on and it was fixed, so I thought.

Bought a scanner and went on a test drive to see if I could see anything. It broke down again and and would not restart. Had it towed to a shop.

The shop replaced the coil pack. A day later it broke down. Towed again.

A local shop has replaced the coil pack with a OEM coil pack.

I made it 2.5 miles before it stalled again. I got it started again, and made it back home.

I originally had one dtc. P0030 O2 heater circuit before any of the coils were replaced.
I tested the A/F O2 sensor and read 870 ohms across it. I replaced it, and the code cleared.

I ran the car for 20 minutes and the engine stalled. I restarted it and 3 minutes later rpm dropped to 300 rpm. The engine sounded like an old carbureted car that would diesel after shutdown. The engine recovered, and I noticed a black cloud out the back of the truck. It then died again.

Engine turns over, no start. Checked spark, no spark. CEL lit back up.

Scanner showed P0340, I used the OEM manual to diagnose this. I found high resistance in the ground circuit. Traced it down to a harness connector between ECU and CMP connector. Cleaned contacts and this cleared the code.

Now I am stuck. Still turns over, no start, and I checked spark again. No spark.

Additional information:
- Fuel pressure gage attached and measured a steady 35 psi, even through a stall and shutdown.
- I had an inductive rpm gauge connected to Left front plug wire.
- I had my scanner plugged in.
- mileage 124k

 

Do you have injector pulse? It may just be the cam or crank sensors going bad. I would just ohm them out to see if they are not open.

I removed both of them and they both checked good. Connected a VOM and passed a ratchet head passed them and had identical readings on a scope. Checked harness for problems, nothing was found.

Did you check for power, ground and control to the ignition coil? It is a 4 pin coil, right?

Yes, it’s a four pin plug to center pins are power and ground. The other ones with the trigger.
Yesterday I checked the ignition control circuit again. Installed my spark tester and held the throttle To the floor as per the troubleshooting chart and it started. It ran for 10 minutes and then stalled Like a carbureted car dieseling after shutdown. I had the scanner connected and no codes showed up.

If you are only losing spark, the focus needs to be on the ignition coil an ignitor circuitry. If you can get the vehicle to start again, can you monitor the two wires going to the ECM until it dies to see if they drop before stalling? That will require a scope.

I borrowed a Solus Edge and I think I spotted the problem. I attached a screenshot. Would I be correct in saying the CPS is defective? Shouldn’t it be showing a squarewave all the time?

At higher rpm’s the signal would have large gaps. At idle more would show up.

 

Both signals look kind of weird, but crank looks worse.
Usually with a crank or cam sensor issue, you lose both spark and injection pulse. Are you missing injection pulse as well?

No

I replaced the crank sensor and I ran it for 30 min and didn’t have any issues. I plan to go for a drive in the morning around the neighborhood with the Solex plugged in.

Hopefully, this will be a fix.

No such luck. Drove it around and had one hiccup, then ran fine. Went back home and let it idle. It shut off. I restarted it and it shut off after 2 min. Scanner showed injector pulse, both CKP and CMP signals.

I would monitor the coil and its circuit for dropouts before the vehicle stalls. that way, you would know if you have a defective new coil, a wiring issue or an ECM issue. I don't really know what else it could be.

We also need to make sure that we are not losing fuel pressure before the stalling.

The Solis lists a number of items that would cause a no start. I checked most of what was on the list earlier. One thing that does not Match the manual is intake air temperature sensor. I measured 2.3 V book says 3.1 to 3.4 Other items listed that I haven’t checked yet is EGR valve intake, air valve, and PCV valve. Would any of those cause my problem?

Even if they were to cause a no start, they wound not cause the no spark condition. Until we find the reason for the no spark, we won't be able to fix the vehicle.

LOL, I watched that video yesterday.
I have attached a engine schematic.
 

Does this happen to be your ignition coil and ignitor wiring diagram?

Has your car been a crank no start since you replaced the crank sensor or has it been intermittently starting? Have you ever tried scoping the 4 wires going to the coil doing cranking or before stalling?

Yes, that contains the coil pack wiring.
The Solus Edge is the only thing I borrowed that works. The Snap On Vantage I borrowed is inop. What would you recommend for a low budget scope?

Sorry, since the crank sensor it has been intermittent start. The crank no start happens after it warms up so far but very intermittently.