CaramelBwoi

Hey guys, I have an 04 350z with 45,000miles on it...just took it out of winter storage and 2 days later an engine misfire?! Only running on 4 cylinders! The vibration is extremely heavy, and sounds like a WRX...Also, 2 cylinders have low psi! Took it to nissan and they told me that i had a multiple cylinder misfire and that i will need a new motor??? (Which is ridiculous) I recently took it to get another opinion, and they had said that there was a misfire and i was only running on 4 cylinders...Took a look at the plugs and 2 had motor oil and grime on the tips, and the piston heads had the same, grime and oil on top...is this just a blown gasket, blown rings? Or will I really need a new motor? Any advice is much appreciated...Cheers. *
2 cylinders have LOW psi!!!*

RandomHer0

iTrader: (9)

Have you tried replacing those 2 plugs?

CaramelBwoi

Not yet, Im doubtful it will help with the low psi issue...

RandomHer0

iTrader: (9)

Oops missed that part...Did they give you the exact numbers?

CaramelBwoi

something like 80psi...

HondaKiller

iTrader: (5)

start with the valve gaskets to stop the oil from getting into the plug area. Replace plugs, then check rear main seal. New engine? Probably not, some work, time and $$$ absolutely.

Skrilla

iTrader: (15)

There is little change the Rear Main Seal and Valve Cover Gaskets surrounding the spark plugs are going to affect cylinder pressure. The majority of pressure sealing from the spark plug come from threading, from screwing in the spark plug, not the oil gasket. Even if oil leaked on top of the spark plugs there is a metal pressure gasket (not oil gasket) resting in the the middle of the spark plug, and any oil that leaks there cokes creating more of a seal. Separating the engine oil from the combustion chamber are the oil seal rings surrounding the psitons. The real culprits of the cylinder pressure issue is going to be a head gasket and piston compression rings, either way *if* you have cylinder pressure that low you have only 2 choices, replace engine or rebuilt it

CaramelBwoi

hmm, thanks for the help...looks like im going to have to swap it...i was debating on just throwing in another vq or doing something different, sr20, or an rb...the main problem though is that they dont make mounts for the vq to hold an rb26...nor the sr20...i would rather do something of that nature than to boost a vq...but thanks for the help!!!

Skrilla

iTrader: (15)

well if you're going to replace it I'd skip the RB and the SR, Nissan racing used the turbo VG motor (think 300ZX) since V6's are less likely to starve themselves of oil at high rpms than I6's.The SR motor, well, its just too damn small, I don't think you want to spend the sick money it will take to get that little 2 to rev on boost and have enough TQ for city driving. I'd strengthen the internals of the Z or do the only other swaps I liked; 3 rotor wankel (yes 3) or LS swap, both of which will require custom motor mounts. Really though I'd say for the money your best bet is a modified VQ + boost.

Were you or any of the techs able to arrive at a reason 2 of your cylinders failed, were the cylinders on the same side of the engine? I have a couple guesses, depending on temp, your head gasket may have suffered extreme temp differential from being stored, at low temp(but I don't know) and turning it over cracked the head gasket in some vital places or there was no fuel pressure after sitting for so long (would be wise to prime it) and it suffered an extreme lean condition (very likely with higher oxygen content in colder air). I was also thinking that the pistons rings might have hit some rust but our engines are aluminum making that a slim possibility. Anyway to prime the fuel lines and give minimum pressure on 1st starting it up turn the key up until the crank position, you'll hear the fuel pump charge the line, turn the key all the way off. Do that one more time before you crank it, and you'll have plenty of fuel pressure.