so im getting an idle misfire on #1 throwing codes 316 misfire on start up and 301 #1 misfire. checked data with dash command and shows that its only misfiring at idle. any throttle and it goes away. did a compression test and got

#1 - 170
#2 - 170
#3 - 170
#4 - 175
#5 - 60
#6 - 180


from the way i understand it is that the pcu reads rotation from the crankshaft position sensor and when theres a drop in rotation speed it reads that as a misfire and assigns it a cylinder based on the position of the sprocket on the crank. does the cam synch sensor have anything to do with this diagnoses by the pcm? just asking because when i instaslled it im not positive if it was on #1 compression stroke or 180 off and #5 is opposite in the firing order and thought it may be confused as to which cylinder it thinks it is.. just a thought..

did the leak down test and have air blowing into the crankcase. not sure why a rebuilt engine with 30 miles on it would be leaking that much.. broken rings or maybe cracked piston would be my guess but before i start tearing into it is there anything else it could be?

 

Compression is mechanical, so nothing in the electric system can effect it.
60psi is usually a valve that isn't closing fast enough, hanging or bad seat
I would test #5 dry and then wet to see if it is rings or valve.

I assume when you said you heard air in crankcase on leak down it also means you did NOT hear it at exhaust pipe or intake throttle body

Yes, CKP(crank position) sensor reads a Tone Wheel that has 35 teeth, one every 10deg, and one missing tooth that denotes #1 TDC, for 360deg
But #5 and #1 are both at TDC at the same time and alternate firing as one is on compression stroke and one on exhaust stroke.
But computer can detect which is which after startup by opening injectors for each and see what power is added so just takes 1 or 2 seconds for it to ID #1 and #5 compression stroke.

CPS(cam position sensor) can also play a part but is secondary to CKP sensor in this respect, CPS fine tunes sequential fuel injection, so most of the fuel gets IN the cylinder and less on the sides of intake/head ports and back on intake valve.
While you need to get CPS timed closely, the computer adjusts this timing for best injector open time based on O2 sensor data and power added.

Computer "knows" how fast each CKP tooth should pass by the sensor at any given RPM or throttle position, i.e. accelerating or decelerating.
So it can narrow it down to one cylinder that is not contributing to crank speed, but 316 means there is a misfire and it either can't be ID it to a specific cylinder yet, or there is multiple cylinders misfiring, but not in any order

CKP pulses and CPS pulses are also compared by computer, so if one is off the CKP sensor is used and computer will set a code that CKP and CPS do not match

 

so it seems as though the cam synch does id the cylinder.. i reversed the cam position sensor to the opposite tdc stroke for #1 and now the dtc is for #5 misfire..

at higher rpm can hear a knocking or more of a rattle sound coming from #5 and and with the plug a bit oily and 60psi compressio . im thinking broken rings.. already ordered the head gasket and bolt set but its hard to find rings for just a single piston any suggestions where to look?

heres a picture of my trouble codes.. 316 misfire on start up 305 #5 misfire and the torqueconv. stuck switch.. reminds me that my O/D light was flashing at me yesterday.. had other issues to deal with and forgot about that one.. also cant see in the picture but pending code is a 301 #1 misfire from before i switched the camsynch..

 

Have to ask, after only 30 miles on a rebuilt engine, how did the ring(s) break ?

 

Good info there, that 3.0l software always surprises me, CPS position shouldn't effect cylinder ID
But I have read that no CPS signal will cause a no start in 3.0l, which is also an oddball setup