'99 S70 AWD won't start, cranks fine

[burnout8488]

Friday afternoon: Started the car in my driveway, it fired but stumbled BADLY upon ignition for about 5 seconds, then smoothed out and idled properly. I drove it to the junkyard with no issue, and it performed perfectly even in some WOT sprints.

After working in the junkyard for an hour, I went back to my car and it would not start. Cranks forever, but would not ignite. Had to get it towed home. I checked spark in the parking lot, and it is firing, seems slow though or out of time. The car is getting fuel, it has a new pump and generously sprays fuel out of the test port.

I tried a spare MAF, no change. Unplugging the MAF made no change.

Saturday: I got a yellow label ETM off of a running 2000 S80 T6. Installed in the car, and now the engine will constantly stumble at 100-200rpm while cranking, but immediately dies once I stop cranking. It seems as if the timing is off, badly.

Tested the crank position sensor, 119 ohms. Another member stated that their new sensor shows 120 ohms, so I can rule that out. The tachometer produces a reading every time I crank the engine. I am unsure if my Cam position sensor is faulty now, or if it's my ECT.

The car threw a P0238 - Turbo/Super Charger Boost Sensor A Circuit High code today. I removed the MAP and IAT sensors, cleaned them, no change. After clearing the code, it has not reappeared again. Perhaps it was thrown as a result of something else.

When I unplug the ECT and/or Cam position sensor and crank the engine, it does not stumble or fire at all. When it's plugged back in, the car roughly stumbles and will not start.

Does anyone have ANY idea what my problem can be? I've tried nearly everything. Let me know if any more information is needed, thank you!

[burnout8488]

Tried a new coolant temp sensor, no change.

[burnout8488]

Immobilizer antenna ring checks out at 5.3 ohms. Should be working then.

[burnout8488]

Going to pick a MAP, IAT, and cam position sensor off an S80 T6 today, will update the post if any of it works, for the sake of helping someone else in the future hopefully!

[Etheraldreamer]

I wish I had something that could help... But very interested in what it ends up being... props for documenting the issue even if no one speaks up to assist!

[burnout8488]

I wish I had good news, but here goes some more documentation....!

Does anyone have any input on this?

I replaced the MAP, crank position sensor, and cam position sensor. No change. I am fully out of ideas, if anyone can throw some knowledge at me it would be much appreciated! The car just misfires and stumbles while being cranked and never turns over. The exhaust afterwards smells extremely fuelly and burned.

[jblackburn]

Your timing belt hasn't jumped, has it?

It may be time to try the tablespoon of oil in each cylinder trick - your engine might be pretty well flooded by now and have no compression to actually start.

[burnout8488]

I doubt it, unless my car just hates me. The car was running and idling great, then I parked it. Went into the junkyard, came back, and no start. The timing would have had to jump a tooth when I turned the car off... if that's even possible.

When I took the plugs out, they were definitely gassy. It still fires a little though, just completely out of time.

Could it be the ECU? What else controls the timing of injectors and spark, that I haven't already replaced?

I've checked a bunch of ground straps, and they all look fine. I haven't found one wire on this car that looked damaged.

[burnout8488]

Fuel rail removed with injectors - cranked the engine and fuel sprayed out of all five in a sequence that looked correct.

Original ETM re-installed, no change. ETM ground on the block is clean and tight.

Knock sensors have been disconnected and checked, no change.

[burnout8488]

Voltage drop test performed on the fusebox, 0 drop. 12.71v at the box and at the battery. Timing gears appear to be aligned properly.

ECU fault?