2016 Chevy Camaro 3.6L P0016/P0018 (& Need Cam/Crank Known Good Waveform)

Hey all,
I'm working on a 2016 Camaro 3.6L Automatic with 132K miles. About 100 miles ago it set P0016 and P0018 codes (no other codes) for "Intake Crankshaft Position – Intake Camshaft Position Not Plausible Bank 1" & Bank 2 (see screenshot.) There is no noise nor other driveability issues. I looked at intake cam variance data and didn't see any immediate problems--see attached screenshot. I found a bulletin that talks about the Intake cam Park Lock solenoids that can break or stick so I pulled one and looked at it. They looked fine. They are only $14 each on RockAuto for the genuine GM solenoids so I ordered a pair but haven't yet put them in.

After my initial look at the car I reset the codes and gave it back to the owner pending more time and awaiting those solenoids and figure I'll replace them since they're so cheap. I now have the car back, 96 miles later with all monitors run except evap, and no codes have reset. I know these engines are known to have timing chain stretch issues so I'd like to get a cam/crank correlation waveform, which I'm planning on doing tomorrow (3/11/22,) but I don't have a known good waveform for this engine to compare it to. Does anyone have a known good waveform they can share? I don't have a Pico but I do have a Vantage Pro and an Autel MP408 4 channel scope, and am planning on using the MP408 to get the waveforms.

Also, if anyone has any tips on this engine and these codes I'm open to them. I've been trying to wrap my head around all the various solenoids this thing has. It has some kind of intake cam park lock solenoids that mount in the front of the timing cover (mentioned in a bulletin that stick and can break,) a pair of intake/exhaust solenoids mounted vertically in the front of the valve covers, and then a solenoid about mid-way back mounted horizontally and sideways above each of the valve covers which appear to be for intake. I've got access to Alldata and have read it but still am confused about which solenoids do exactly what.

The attached screenshot is of the intake and exhaust cam position variance during snap throttles. Both show momentary variances up to 6 degrees but since the exhaust shows those same momentary variances, and aren't setting codes, I wasn't too worried about that. Seems normal to me unless I'm missing something. They're steady at 0 at idle.

Thanks,
John

I finally found the system description in Alldata and think I understand the system. The sideways solenoids on top of the valve covers are rocker arm oil control valves. Not sure just what those do but, near as I can tell, they don't seem to be related to these codes.

I found an Alldata diagnostic bulletin that says to first change the oil & filter (owner says he recently did that but I may do it again,) then change the camshaft position actuator solenoid valves. If the codes go away after either then you're done. If not, go in for the timing chain job. That seems like the parts cannon approach but those actuators aren't all that expensive. I'm hoping I can get a known good cam/crank waveform and know before changing all that if I need to do the timing chains.

Also, Alldata says it's 25 hours of labor to do the timing chains on this car. There is a ton of room in front of this engine and it doesn't look that bad. Does anyone know...Is that 25 hours really correct?

This is a 2008 3.6L

Intake cams line up with each other. Exhaust cams do not.

Thanks for this! There are lots of the older 3.6 waveforms out there but this newer LGX 3.6L is quite a bit different so I'm not confident in using those. I'm hoping someone has the later LGX, 2016 and up, 3.6L waveform.

I did find one on an 2010-2017 Equinox LFX 3.6L engine that looks very similar to yours, if not the same.

I've now figured out what the rocker arm control solenoids are for. I didn't realize these 3.6L engines had AFM. Those are the solenoids for AFM.

I'll update again tomorrow when I get my cam/crank waveforms.

I got a cam/crank waveform today. It's just the intakes since that's what I had codes for. Bank 1 is on the bottom, Bank 2 in the middle and crank on the top in blue. My crank waveform looks different than all the others I've seen but appears to be a 60 -2 reluctor. If the above are known goods for the LGX engine then, as far as I can tell my bank 2 intake cam appears to be retarded about one reluctor tooth, or 6 degrees. The bank 2 cam appears to be retarded about 8, maybe 9 degrees.

I've watched a ton of Paul's videos (and others) on this but this is the first time I've actually done one of these myself. I welcome any other opinions on what I'm seeing in my capture.

Thanks
John