1990 nissan 300zx trouble

[Duke51]

Hey guys so I've been trying to figure out whats wrong with my 1990 300zx 2+2, i bought it back in november and when i bought it it seemed to be running fine. On the way home it just died for no real reason, i have some other posts that explain it a little better, so i can get to the point. After a couple months of my dad and i working on this car and consulting with a mechanic we were unable to find the problem so we took it down to the shop at my school. There they have been going over all the tests we did, along with some others. What i do know is that spark, fuel and timing are good the exhaust is not clogged the sensors are working and all fuses are good. The mechanic just recently did a compression leakage test and seems to think that the intake valve on cylinder 2 is stuck open, now my question is if that is true would that keep the engine from starting?

[t.mcginley.jr]

No, a stuck valve shouldn't prevent it from starting, but it would cause it to run like total crap. There are also 2 intake valves (and 2 exhaust valves) per cylinder, not just one.

What style PTU do you have?

[t.mcginley.jr]

And I'm assuming you've already checked for error codes?

http://www.nicoclub.com/archives/nissan ... ostic.html

[Duke51]

okay thanks, this whole thing is really a brain picker the car was working fine and then on the way home it crapped out, the guys in the shop have been doing a lot of test all coming back with no real results. The engine tries to start and it almost gets there, but it just wont start. It is throwing one code the code for the det. or knock sensor, but i was told that that would not keep it from starting.

[Ace2cool]

I don't see how they would determine it was specifically a stuck intake valve with just a compression test. Don't go to a regular mechanic. They'll screw you with these cars.

Yeah, for sure check ECU codes.

[Duke51]

yeah, well i'm not sure exactly how it works, but they said they did a compression leakage test and that most the air was coming out of cylinder 2 through the intake manifold. i know that they also did a normal compression test and decided that cylinder one was kinda low and could possibly have worn rings, but it's nothing that would keep it from starting.

[Ace2cool]

Sounds like they're trying to weasel money out of you. One stuck valve won't keep it from starting.

What did the ECU test tell you?

[Duke51]

I have it in the shop at my school, mainly to avoid getting weaseled out of money cause i can't say i really trust the other shops in my area, I do trust that they aren't just trying to get money and unfortunately I don't really have the ability right now to get it to the closest nissan dealer to see if they could figure it out. the ecu told me that the knock sensor was bad or that the wiring to it was bad, but that's it no other codes. I put new spark plugs in it, a new fuel filter new air filters a new ptu, took the exhaust off to make sure they weren't clogged. I checked fuel pressure and it's good the injectors are working the CAS works. I had to replace the camshaft oil seals, and when i did that the timing belt looked like it was only a couple months old but i replaced it anyway just to be safe, all timing marks lined up before and after. I doubled checked to make sure that it had not jumped a tooth and it didn't. I've looked on the internet to see if anyone has had the same problem and came up with nothing. I still can't seem to figure it out i even replaced the battery and checked the alternator.

[t.mcginley.jr]

Can you get a video of you trying to start it? It might help diagnose it.

[Duke51]

yeah i can definitely do that, ill have to do it tomorrow though and then ill post it tomorrow too

[Ace2cool]

And definitely don't take it to a Nissan dealer. Most dealerships don't have factory trained Z32 techs anymore. They've all either retired or moved on to something else. So the maintenance will be even more expensive, since they'll have to research, and that adds up hours as well.

[J30tChumpCar]

Something as simple as diesel mixed with the fuel will do as described, take a sample and pour a little on CONCRETE (in a safe place), allow to evaporate and or burn , if it does not completely dry suspect contamination. Hint: have a known good sample of good gas to compare results with.

[Duke51]

Hey guys sorry it's been so long and sorry for not posting a video I've been really busy lately. So here's where I'm at, the shop finally got the Z started good news! bad news there's a terrible knock (that wasn't there when i got it) on the passenger side most likely due to a rod bearing woooo. The shop isn't charging me and ill be bringing her home to pull the engine and rebuild it. So my question now is does anyone have any links to a site with a good step by step procedure to removing, rebuilding and installation? Main concern is the removal and rebuild install shouldn't be to hard haha anyway all help is more than welcome thanks!