1990 300zx na Auto 2+2 wont start

[Raw Z]

Update: Replaced the ignition coil relay and in the process, I left coilpacks 2, 3, 4 and 5 open (may have evaporated moisture) and it started but sounds like its running off 4 or 5 cylinders. Now it sounds like its time for me to learn this compression test...

[DCaff300ZX]

Check your electrical connectors for green crud (corrosion) which is very common, and can easily cause what you describe.
The OSM in the "everything you need to know...Z32" sticky is a great resource for what you are about to undertake...

[Duke51]

Damn It's been a long time since I've been on here.
The original issue that I was having was with the CAS, within the casing a screw had come loose and was basically bouncing around inside getting in the way of the sensor causing it to have all sorts of wacky readings. Once that was fixed we were actually able to start the car and it sounded like crap, "knock knock" "whose there?" "not your rod bearing" haha funny now wasn't super funny then.

Now knowing it had a knock I pulled the engine and began to break it down, to find out the extent of the damage. S here is goes and its not good, I can only assume that the previous owner never checked their oil levels. On rods cylinders 3 and 4 the rod bearings had started welding themselves to the crankshaft and the bearing surfaces themselves on the crankshaft were so chewed that resurfacing was out of the question. I believe in was rod 2 that was actually bent and the cylinder walls were in no better condition, scared. After seeing this I don't know how I was able to test drive it and how I could've so foolishly overlooked the knock, maybe it was the desire to have sure a cool car.

So the search started for a new heart, I was lucky enough to find a car in my area that had been in an accident. The engine from the new car had been well maintained with roughly 80,000 miles on it and a new transmission replaced under warranty. I swapped the new engine and trans in and got her back on the road. Currently I'm working on doing some custom interior work that includes deleting the rear seat, lets be honest nobody fits comfortably in those anyway.

[Duke51]

Raw Z have you tired switching the coil packs around? if 4 and 5 sound dead, switch the coil pack with one of the cylinders that's working and see if that changes the dead cylinder. Could easily just be a couple bad packs.

[Ace2cool]

RawZ: Do the power balance test by unplugging coil packs and seeing if the idle changes when you unplug them. If one doesn't change, then that's your culprit cylinder. More than likely will be a dead coil pack or stuck injector.