[cyow5]

Alright, so it sounds like these two commonly coincide, but I want to start by taking a step back and asking if the Carly "Last occurred at" mileage is reliable. If I clear my codes, these two come back, but it says 20,480km for the DSC error and 227,840km for the CPS error. Currently, I am at 227,850km, and I replaced the CPS sensor last night. Should I ignore these and assume they are just persisting in memory for some reason, or should I assume they are new codes?

Assuming they are relevant codes, here's where I am at now. A week ago, it started taking a noticeably longer time to crank. It'd just spin and then finally light off. For the remainder of the drive, I had a DSC light on and gutless power at low rpm. I was planning a lot of maintenance anyways, so I broke my cardinal rule of never throwing parts at a problem and replaced a lot that I knew should be done just because of the miles (145,000 miles). I replaced:

Battery (old one was a '14)
Water pump (unknown age)
Thermostat (unknown age)
Oil pan gasket + bolts (was leaking)
Intake VANOS
Exhaust VANOS (possibly damaged during install, got a CEL, put old one back)
Crankshaft Position Sensor (used, unknown miles, worked when pulled)

I replaced the CPS last night because, prior to that, I still had the extended cranking, low power, and 002A95 ("last occurred at" miles made sense that time, too). A friend had a spare motor, so he let me have the sensor, so it isn't like he is some shady ebay seller. This morning, I was driving and consistently it would buck hard at 3,000rpm. CEL would come on then off (not blinking, just not set on). In neutral (manual), I can rev it to 4,000rpm just fine.

Thoughts? I am letting the car cool off before I lift it back up and make sure the connector on the CPS is solid and the wires didn't get loosened up. That's about all I can come up with at this point that could fit the chain of events.

[cyow5]

CPS seems okay, nothing obviously wrong or loose at the connector. I did notice it had grabbed some crud when I first put it in, so I cleaned it up and reinstalled it. I also noticed my ground strap was trashed, so I replaced it.

I put the car back on the ground, cranked it up, and let it idle for a while. RPM came down as it warmed up, and everything seemed fine, but that’s how it has always been. I took it for a drive, and it immediately stumbled around 3,000. Strangely, there are no pending or actual codes now, so it is acting like one of those two changes helped with the crankshaft issues but not the stumble. The stumble is downright violent though - feels like the brakes are being jabbed. I turned off DSC/TC, and it still did it.

Going to look at the valvetronic tomorrow and try a new eccentric shaft sensor. Anything else?

[cyow5]

Good feedback, everybody.

Couldn't get a hold of the eccentric sensor today, and I am heading out of town for a few days, so I'll revisit troubleshooting next week. I did get new injectors and rail in today, and I got the valvetronic motor out. It had been slightly leaking for a couple years, and I had just assumed that it was residue from a bad spill awhile back when doing an oil change, but I am thinking now it is new. There was also some puddling by the #3 and #4 coils as you'd expect for a valvetronic leak. Eccentric sensor plug was dry, but I'll replace it anyways since the time of tearing everything apart is the more valuable than the 140,000 mile sensor on there now. Injectors also didn't look too pretty, and they had some crud past the o-rings, so I got that all cleaned up. Any number of these issues has caused misfires for others from what I've read, and oftentimes with no or misleading codes. I don't have a good reference for what it should feel like, but I always thought idle was a bit rough when running AC, and there was an occasional stumble off idle that I just assumed was bogging, but could've been a misfire. Here's to hoping these issues get cleared up with all this work...

[cyow5]

Alright, UPS says new valve cover gasket should arrive today, so I am hoping to start buttoning all this up tonight. Any last minute ideas before I do? Is there anything obvious I am missing? If none of this resolves the bucking, I am just about out of ideas, so I am really hoping this gets it. Otherwise, there may be a cheap E91 on the market soon...

[cyow5]

Latest update:

With the exception of one seized valve cover bolt that had to be extracted in four pieces, I got the valve cover back on without a lot of trouble. So far, no oil leaks anywhere, but it still does the bucking around 3k rpm. From what I have dug around and found on the internet, I don't see anything that actually fits what I am seeing, and the harsh bucking didn't occur until after changing out the battery, water pump, oil pan gasket, and VANOS solenoids. The changes since then have not made any meaningful difference. The part that throws me off is that it cranks fine and idles fine. Low rpm torque seems improved over where it was when having the long cranking problem. Basically, everything seems okay until bucks, and then it is only after bucking that it idles weird. When pulling back in my garage, it idles smoothly still and then all of a sudden revs up and dies. This rev-and-die after idling smoothly sounds like a vacuum/PCV/evap kind of issue, but I have not seen anything obvious, and I have not heard any whistling.

[cyow5]

Conclusion!

When I removed the old crank sensor, its gasket had stayed in the block, and I hadn't noticed. When I put in the new sensor and its o-ring, the two o-rings were stacked, and that was the culprit for everything *after* the first post. Not sure where along the line I fixed the original issue, but I am thinking it was the original crank sensor going out.