I have a 2003 Nissan 350z with 95k miles. Always used to run perfect. I just replaced my valve gasket & after that my car was running terrible. My idle would drop and it sounded like my Z was cammed.
I ran 2 codes: MAF Sensor (Replaced) & Camshaft Sensor (Replaced Both)
My car would stall sometimes when I put it in neutral from 2nd gear coming to a stop. My car just died earlier today & I couldn’t start it.. It would just crank to the point where I had to push start it..
Any suggestions? The code it’s still throwing is:
P0021 - A Camshaft Position Timing Over-Advanced or System Performance Bank 2.
PLEASE HELP!! Thank you to everyone in advance.

 

ALSO: A bolt snapped while I was tightening my intake manifold. The bolt was #4/18. Ordered it just waiting, but what can the other problems be?
Thanks guys!

 

I did the exact same repair on my 05 350z, I accidentally didn’t connect the coils back the same way and it missed fired pretty bad before I turned it off real quick cause I noticed sounding a lot deeper while at idle. I’m not sure if it had something to do with the valve timing solenoids not working properly but. I found a forum on here for the same problem and the solenoids being replaced fixed it.

 

Before I replaced the valve cover everything was running perfectly. I didn’t touch the solenoids throughout the process but you never know it might’ve just gone bad. I just sprayed brake cleaner and I found a leak which made my car die. On the upper plenum towards the back left corner (facing the engine). Do you think that would cause my car to just crank? Thanks man!

 

Well as far as I understand it doesn’t at all like a mechanical issue. It most definitely is something electrical related, so check your wiring, did a pin fail out of the connector? Are your connectors not fully clipping into the sensors? You could have also shorted something out go through just verify all fuses are good. Make sure all grounds got connected properly and don’t have any corrosion. Clean out the connectors also for any dirt and debris. Could be as simple as maybe you didn’t connected something. But obviously you didn’t mess with anything mechanical. You’ve air, you’ve got spark and gas. So it’s just a matter of wiring

 

Just took off my upper plenum to try to find where the leak was coming from.. & I saw that my (lower plenum?/intake manifold?) not sure what’s it’s called.. but it has a crack in the corner! From over tightening the bolts I’m assuming. Do you think that would cause my car to not start? Sometimes it won’t start & I’ll try again within 10 seconds and it will start.. Thanks for your replies

 

yes, I believe this is the culprit as too much air especially behind the maf sensor will throw off the air reading causing it to throw a bad code and also will mean your car will run very rich which will make your timing off, definitely the problem.

 

I replaced a new MAF sensor so I’m not sure what I should look for to replace next? Thanks

 

No, it's most likely not.

OP, you really need to fix that crack in the plenum. You have a vacuum leak now. That is why spraying the cleaner had the result that it did. You have additional air that is unaccounted for throwing everything off.

 

Bought a new lower plenum & now there is no leaks. The car doesn’t die while driving anymore. But when it’s warmed up & I turn it off, it won’t start up again. Only when it cools down. I heard it might be the coolant temperature sensor so I ordered one of those as well as a new PCV valve since mine broke. What do you guys think the problem can be? I will post an update tomorrow once I throw all the parts on. Thanks!