hello, my car is a manual 2004 track 350z 75k. the car only misfires when driving it, while driving it the car kinda likes hold back intermittently. There where no SES codes at first then a day after i got P0304 cylinder 4 misfire, changed the coil with an OEM one, and the problem keeps going but the P0304 code has not come back on. It started while i was driving and then only did it at lower RPMs now it does it at all RPMs, I can accelerate it all i want while in no gear, and does not misfires. Any ideas on what could cause this before i take it to a mechanic???

 

Have you pulled the plugs to check any of them? Are they still the original NGKs?

 

No i have not, i dont know if the previous owner changed them. That could cause the problems? I was told it could be the fuel pump too. Thanks btw

 

Of course, spark plugs can be a primary cause of misfires. Since you're not sure of what the previous owner used, you may want to do a visual inspection. Even the use of an aftermarket plug can cause ignition and misfire issues. Look for color changes or a damaged electrode or insulator as signs of a problem.

 

You may have an oil leak that is drowning your spark plug, oil fills the chamber of your spark plug/coil pack....then the oil will eat away the rubber that is sealing the spark plug.

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just an update on the car, the electro-mechanic said there was something wrong with the wiring on the car, was not very specific but got it fixed!

 

You should ask your "electro-mechanic" for more details about exactly what was wrong with the wiring on your Z. Nissan harnesses are very robust and any cuts or breaks are something you need to know about for the future.

 

thanks for the heads up!. by the way electro-mechanics, at least here is what we call mechanics that specialize in electrical systems of cars(not many), when all other normal mechanics are scratching their head to guess whats up(or throwing parts at your car then charging you,because the car wont throw OBD codes), these guys(electro-mechanics) get your car running in a couple of days if not less.

 

I actually like the "electro-mechanic" moniker.

Over here, we generally call them diagnostic specialists. They understand how to use waveforms (and other mechanical methods of diagnosis) to establish and point out the problem. Then the parts-swappers get to work.

A good example of a diagnostic specialist on YouTube is ScannerDanner. His channel is located at https://www.youtube.com/user/ScannerDanner

Duane from Real Fixes Real Fast is another expert-level diagnostic specialist. His channel is located at https://www.youtube.com/user/realfixesrealfast

There's a lot you can learn about basic diagnosis from both these guys. You can get a cheap 2-channel scope (the one I use is a Snap-On from the late 1990s) and a decent OBD-II scan tool to figure out most issues with your vehicle. Sometimes though, it's all about experience and simply knowing where to start.

 

Ohh thanks for the info!, definitely gonna check out those channels.