Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Infiniti M56x VIN # JN1AY1AR9BM570450
Car lot replaced the engine and could not get it started. Sets a CKP code. With the Crank Sensor unhooked it will crank for a bit and then start and run but not the best. Shuts off at around 53 mph.
I am an Automotive Technology Instructor for two high schools and my approach is to look at everything on the vehicle through current flow and scope patterns. I have looked everywhere I can think of for a scope pattern showing cam/crank and hopefully cylinder pressure waveform on this engine but I have not found any that I thought was actually correct for this 5.6. Nissan makes a 5.6 that doesn't have variable valve timing on all 4 cams but this one does and I am pretty sure the crank sensor pattern should be different as well.
Any chance you can get me the waveform?
The car lot is adamant that the engine is out of the exact year make and model plus they replaced the flywheel and ordered it by VIN from Infiniti so I am leaning towards an actual internal timing issue in the salvage yard engine but without a known good scope pattern I feel it is too intense of a diagnostic process to work through with my highschoolers.
We just had a xterra in our shop and the guy next to me had just replaced the transmission and then it wouldn't start. Had crank ps codes. The new flywheel was bent slightly. It also ahd the long cranks until the cps took over then ran poorly.
Nevertheless, try to get your hands on an USB autoscope (that is the name of an engine analyzer/osciloscope) and run the provided Px and CSS scripts. You will be able to identify mechanical timing issues without reference waveform.
Her is a link to ho the Px script works.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
I had a Nissan in the shop a while ago that had the transmission replaced and would no longer start. After quite a bit of back and forth support I torqued the mounting bolts properly and it started and ran for a while then died. After doing a high frequency scope pattern of the crank sensor it could be seen that the crank signal was getting cut into smaller sections due to magnetic interference. I was told about a Nissan with a similar issue that would not start and had one bolt missing from the transmission housing after an engine swap - simply pushing a piece of metal in the empty hole got it started - it caught the magnetic interference that was going in front of the crank sensor.
With the vehicle I was working on the only way to get around the magnetic interference issue was to grind the crank sensor hole bigger, wrap a piece of thin metal around the sensor and give it a good earth on one of the mounting bolts - after that it started and ran perfectly.
Getting involved in discussions because I have a lot to learn still.
But I agree that you're looking at a mechanical timing issue. Classic Nissan/Infiniti symptom. 
