I've been driving this but haven't done much to it lately. Seemed to run ok but wondered how much better it would be with a tune. Got a mail order PCM from Black Bear a couple weeks ago. After installing, it started spark knocking a lot under load. Checked a few things, nothing obvious. Replaced the plugs, cap, and rotor because they were not high quality and pinging improved but was still there. There was a little oil on one of the plugs so I checked compression against another cylinder and they were similar. Hopefully it's just because the engine is new and still breaking in. Engine is supposed to be 9.1:1 compression suitable for 87 octane. Tuned for 87 as well. But 175-185psi seemed kind of high so I tried 93 in it. Spark knock went away. But then I got a CEL for bank 2 long term fuel trim too rich. Cleared it and it came back. Contacted BB for advice, they said they didn't do a whole lot to the fuel trims so it's probably not because of the tune and it could be a faulty MAF. I replaced it and it seems to have fixed the issue.
I don't know a whole lot about computer controls but a few things seem odd to me.
The short term fuel trims are about the same between the banks, but the long terms are -8 and -14%. I don't know if this is an acceptable difference or if something is going on with that bank.
I don't have any misfire codes but while watching live data with the scan tool I can see that cylinders 2, 3, and 4 are getting 10-40 counts per cycle at idle. It's been doing this ever since I put the engine in. Changed plugs, wires, cap, rotor, no change. Seems to have less misfires when cold and more when hot.
The rear O2s were disabled in the tune but are still connected and display data on the scan tool. One of them fluctuates up and down a lot more than the other.
It runs great, no driveability issues. I want it to be healthy, but since I'm not getting any codes not sure if I should mess with it.