Hey, long time lurker, first post.
So let me start out by saying I've done a ridiculous amount of research on why these two motors have blown and I've gotten it kinda narrowed down. I'll write up how the first one blew and then the second one. I will be the first to admit I made some mistakes throughout the whole process which likely led to this happening a second time. So I'm ready for the flame.

First motor:
Stock motor, had about 100k on it and all of a sudden it gave me p0011 and p0300 and I couldn't figure out what was wrong. Replaced both camshaft position sensors and that didn't help. Ended up blowing out my driver side cat, so I replaced it. Shortly after my motor started clanking and getting vicious rod knock or piston slap so I pulled it and put a new working motor in.

Motor #2 second motor went in and gave me exact same problem. I put new cat on driver side. It blew it out so then I got a full exhaust, test pipes and catback. Engine blew after about two weeks.

So I just need to know what to check, do I need an ecu? Wiring harness? What can I do to fix this and not have this problem again. TIA for any and all help.

 

Welcome and gotta say, that's a helluva first post! My first question is what do you mean by the engine "blew"? For most of us, this means a catastrophic mechanical failure that ended with a ventilated block, or some other unrecoverable damage. From your description, it sounds like the first engine did not "blow", but rather, needed a teardown to discover what happened. I have NO IDEA what happened to your second VQ- please specify.

More questions: who pulled the first motor and installed the second? Was the second VQ a reman, or did you just buy a junker? What model year is your Z? What were the "mistakes" you alluded to in this entire process?

 

Thanks for he reply. I have a 2003 350z track edition. The first motor started clanking at 2k rpms and myself and a couple other legitimate mechanics decided on a spun rod bearing.

My buddy had an 04 g35 that ran perfect but he rolled his g35 so I pulled the motor from his g35. And put it in the 350z. Then the same thing happened. No power and all of a sudden a lot of clanking in the engine.

The second one blew out driver side car again and gave me p0011 and p0300 from the first start up. Never gave my buddy any problems before hand.

I only have the 350z so I was driving it to work every day with a p0011 and p0300. So I know that didn't help. But I never drove it hard and kept it under 3k rpms. But it never ran right from the start.

Since it broke the same way the first one did it leads me to believe there is a wiring issue or ecu issue. I've checked about everything I can think of.

I hate people posting on here and not doing their homework, so believe me I've checked, coil packs, injectora, spark plugs, camshaft position sensors, changed fuel pump and fuel regulators. I just figured maybe someone would know how to fix this before I put engine 3 in and blow it as well.

 

So, first of all, you have not blown either engine, but you have damaged both of them. You say you've checked everything you can think of, but the problem continues. To answer you directly, nobody here is going to be able to accurately diagnose what the problem(s) are with your Z from behind a computer screen. You've tried to "shadetree wrench" this issue with your buddies, but where has it gotten you? It's time to spend some money and bring in a trained Nissan tech with diagnostic routines and access to a CONSULT III tool.

 

You can't help everyone.

 

Not wasting my breath, thanks for stepping up.

 

I'm not sure a plugged cat can cause rod/bearing failure. Those failures are generally caused by lack of lubrication or just old tired beat up parts.


Unless extremely jimmie rigged I cannot see an ecu or wiring causing a motor failure either.


Odd bro... Maybe your buddy's G engine wasn't in good shape and just let go. I'm sure you're making sure fluids are good?

 

Can't think of any part that would do that, maybe a stuck injector but I highly doubt that. Swap injectors around and see if the problem follows

 

If he rolled it. he would of had the engine running without oil being pumped through while the car was upsidedown/sideways