Nissan Repair: low engine compression???, 2005 nissan pathfinder, crankshaft sensor

Question
QUESTION: Have 2005 Nissan Pathfinder with 160k miles.  Car started occasionally cutting off while running but would then start back up.  No check engine light ever came on.  Car finally cut out while driving and would not turn back on.  Towed to shop and they found no computer codes to id problem.  Car has both spark and fuel pressure.  Low compression has been id as the problem.  Mechanic has torn down engine and ruled out all the usual; timing, engine block, valves, pistons, seals, etc.  Mechanic has no clue and has now called nissan for help.  I have done some research on my own and come up with the EVAP canister vent control valve or a bad IPDM???  Would these items even affect the compression?  I am uncertain what to do at this point? Any help would be greatly appreciated.  Thanks!

ANSWER: Hello JR -

First of all, what was the compression numbers? That wouold give a clue as to what is happening internally. I find it unsual for the car to cut out (after running a while) on low compression. Normally, it will not start or run rough 100% of the time.

Was the ignition module checked with the tune up items? This is located in the distributor, and is well known for cutting out the engine when it warms up. Lot of sensitive circuit boards and the heat affects it.

let me know about the compression -

aloha
hope this helps -
calvin

---------- FOLLOW-UP ----------

QUESTION: The compression i'm pretty sure is somewhere around 50psi.  It wants to crank but just won't.  The mechanic thought it might be the crankshaft sensor only working part of the time and tried that but it as well didn't work. I asked him about the ingnition module and he told me this car doesn't have a distibutor but ingnition coils?

Answer
Hi JR -

Please bear with me as not being there to physically diagnose the vehicle is difficult.

Are all cylinders at 50PSI? I assume this is a V6 engine, do you have low compression on both banks? It would help to know the comnpression for each cylinder.

Did the mechanic check the timing belt for slipping? You can do this by manually turning the engine to TDC and checking the alignment marks.

Let me know -
aloha
calvin