So I think I have a big problem. Let me first give you the setup of my car.

Nissan 350z 2003
Greddy Twins installed in 05/06
Built Block by SGP installed in 05/06
Haltech tuned by one of the best

Car sat for a while, while I was overseas.

When I got back from Korea I picked up my car in New York where it still had the F Con in it. I drove it 700 miles to get it tuned with the Haltech. We swaped out the Fcon for the Haltech and tuned and dynoed it. It put down 498whp at 15 psi. Okay good Im happy.

I drive another 700 miles to my next duty station. While on my way there I was cut off by some b*tch and was run off the road into a ditch. The car had mud and dirt everywhere, just looked like I went mudding. After the tow truck got me out I started it up and it ran fine. Absolutly noting wrong, A/F was right on, oil pressure good and I was still making boost. Good.

I got her all cleaned up and then went to do some sprinted driving. I made mulitple runs to about 80-90mph to about 7k rpm. Some shifts werent so smooth but nothing to bad. I got off an exit and this is where I noticed my first problem. When I came to a stop I heard a loud kocking in the engine bay. It was loud. At lower RPMs the knocking wasnt too noticable but when reaching 2.5-5k rps is where you can really hear it. I babied her all the way back to post where I just shut it down and waited for the next day to deal with it.

I took her out the next day and it was the same thing, loud knocking as you build RPM, if you kept it in a high gear and RPMs low you would not/bearly hear it. I put her on the lift to check to see if anything got loose and was hitting something.....nothing. At this point the motor is still feeling very strong.

I decided to pull the plugs and check to see if they are still intact. Yup they were still good. No oil on them or anything. They looked good. I was going to do a leak down and compression check but I didnt have any time. So I put it all back together and start it up. Now I am getting random misfires...f*ck. WTF. I connect my laptop to the haltech and notice bank 2 is running lean, A/F 17's, while bank one was 14's while idleing.(Haltech dual widebands). I had to get home so I drove it back really slowly. When I would stop and go again the motor would backfire in the low RPM's when there was a load. This is while the knocking was going on.

So right now I am stuck I dont know what to do or what to check. Some one mentioned that my valve would have to get aligned again, w/e that means. Anyone have any ideas. Thanks

Edit- Sorry for the long *** read

 

likely need to seat ur valves? or if its a bad knock its likely ur block

 

might be a stupid question, but how long did the car sit? did you change the oil before starting up or at least check the oil levels?

 

You should have done a compression check when you had the chance, I would stop driving it also. But it sounds like rod knock from the description.

 

time for a new motor.

 

i'll second the rod knock from the description. This could be a result of the lean bank, if you are detonating a cylinder the rod bearing gets beat pretty good. Quit driving it until you tear it down to inspect it, its only going to get worse and cost you more money to fix.

 

Can anyone explain why it is misfiring. I checked cel and it had all the normal codes that i knew about plus the new misfire code p0300. Can this be a result of cylinder knock?

 

Misfire could be from plugging the coil packs back together wrong, not saying you did but it is a possibility during the spark plug check.

If it's rod knock nothing you can really do, it needs to be rebuilt.

 

Sorry to hear all that trouble at that day. I will defi do compression check first, but is it possible can be your tranny?

It was nice to meeting you at IP.

chefj

 

The more I read this, the more I keep thinking ouch. I hope it not a big problem but from the sounds of it, it definitely sounds like it needs to be checked out.

I'd be so pissed right now

 

Misfires are often a bad plug or a bad coil.

 

Holy COW!!! I hope that's not what I think it is...get it checked bro...ASAP.

 

misfire? no clue, could be plugs, bad connection etc.

Now as for the knock....sounds and awful lot like a spun bearing.

Go drain your oil ASAP and see if there is debree in the oil

tom

 

Let us know if we can help you with anything...

 

you spun a bearing

 

I'm getting the idea that I did actually spin a bearing. What kind of work is involved to fix this? does it just require to replace the bearings? Ughh going to do some searching.

 

Any update?

Edit: the Full way is to teardown and inspect the block. The cheapest way is having teh crank checked and changin the bearing. Basically its rebuild. What caused this? Who knows, may have been leanking while it was stored and low when you got it running again and drove it. Did you check anything before you took it out of storage?

 

I just changed the oil when I took it out of storage. What I don't get is that I put over 2000 miles on it and over 20 hard dyno pulls before this happened. I'm going to have to wait until WED to get it checked out. I'm am leaning more and more towardba spun bearing becuase from the research that I have been reading my car has the same symptoms as other cars with a spun bearing. At this point idk if it would be better to just buy a new shortblock or just rebuild the bottom end.

 

Well could be lucky or could be basket case.

Need a machine shop to inspect Crank (should probably have them get it magnafluxed to check for cracks), and check for straighness/true-ness. Also inspect journals where bearing spun.

You will have to replace all bearings of course. Inspect/replace oil pump.
Hot tank clean everything would be preffered to get any small debree cleaned out of all passeges and whatnot.

Depending how bad the damage you may have to replace the rod(s) of fail'd bearing.

tom

 

I agree ^If he has been driving it with a spun bearing I would think the rod is done as well.

Pull the pan off and if one of the road caps is a different color than the others that is your spun bearing and the rod should be replaced if its a different color than the others they change color due to the extream heat.

If its just one bearing spun
Replace the bearings, the crank may need to be turned and possibly a new rod plus clean and inspect oil passages head and turbos for bearing material dont forget to drain/flush out oil feed return lines. I have seen guys that finish the rebuild put it together without flushing the turbo lines then damage the turbos from bearing material still in the lines.
Good luck keep us posted.