so i have seen a lot of people with this code P0300 but people don't follow up with updates.

my car is a 2003 track with 107,000 miles. everything is stock. oil changed in the last few hundred miles.

symptoms of the car are: when the car is fully warmed up, you can feel vibration through the shifter and a light popping sound through the exhaust. when i start the car from a cold start, it has no vibration and no pop, but as soon as the car warms up and the idle drops to the 650 mark, the car starts to vibrate and pop. no smoke or smell from the exhaust.

while i was driving one day, the ses light started blinking. so i took the car to o'reilly's to get the code read. it came up as P0300 random misfire. i got some ngk premium platinum spark plugs to see if it were the plugs. that didn't fix the problem. i got the code cleared and put some stp fuel treatment in the car and right away the car stopped vibrating and stopped popping. drove normal again but that only lasted for a day.

the old plugs all looked the same and fine. so i'm guessing the injectors are ok too. the coil packs are good too. maf and tb cleaned. i did notice the throttle plate wasn't closed fully when the car was off. like the plate is not completely vertical. i don't know what else might be the problem.

does anybody know a good shop around Portland/Vancouver area that works on z's?

thank you guys for reading.

 

Someone fixed it by changing new injectors. Iirc, one if the injector disnt work properly, and was dumping fuel. But he updated and said it solved the problem. GL!

 

I had a mix of coil packs, injectors, & plugs that caused my P0300.

 

so today i ran some seafoam in the gas tank and did the ecu reset. code never came back and car's been running fine. maybe the injectors were kinda dirty? or the gas in the car was bad? i will keep this thread updated.

 

so I get a misfire intermittently. could it be an injector getting stuck closed intermittently? The misfire usually goes away after I do the pedal ecu reset, but why?

 

so yesterday I had the ses light checked again. finally I was able to get p0305 and p0300. now I can look in to cylinder 5 to see what's going on. the misfire is still intermittent though. I would have the light on the dash steady but the car will drive fine.

 

so can a coilpack or injector intermittently function normal? The misfire goes away with a ecu pedal reset, but why?

 

so I heard coilpacks usually have an underload problem instead of a constant problem. if that's true then that might be my problem. sometimes when I'm cruising, when I get to an incline, the car will drop a cylinder, then the car will smooth out when I'm not climbing anymore.

anybody got oem coilpacks for sale?

 

I have the same problem with p0304 instead. I have changed the plugs and still ses light still on. Next I'm swapping out the coils and see if the code moves

 

are you getting the p0304 and p0300? it could be the valve covers leaking oil into the spark plug tubes. are your spark plug tubes leaking?

 

had the same problem my buddy at nissan put his scanner on it and was able to determine it was a coil pack. he can turn packs off one by one. a scanner at orielys will give a multiple reasons but nothing clear. the only bad thing is once u change one coil pack they others seems to follow one by one. i was stomped for the longest time almost wasted time and money on useless parts..best thing to do is to take it to the dealer and find out ur problem for sure. hope this helps.

 

thanks man, maybe I should take it to the dealer and let them check it out. I never trusted dealers though.

 

Had the exact same issue (misfire when on a warm start) but never got a code for a specific cylinder.

After replacing the plugs and doing some other work, I took a chance at replacing my MAF Sensor. It's been fine since then.

 

My z always has a popping sound, and vibration through the shifter. I never had a light on for it though or driving issues.

 

it still might be having a slight intermittent misfire. you should see if you have any stored codes.

 

Hmmm I check periodically after every oil change and there are never stored or pending codes. Had the car for like 20k miles.. never had it effect driving.

From what Ive researched it's common with the z and has something to do with a fuel hose or something.

 

https://my350z.com/forum/maintenance-and-repair/265981-sputter-pop-idle-what-s-wrong.html

 

so I switched coilpack from cylinder 5 to cylinder 3. now I have a p0303 code. anybody have coilpacks for sale?

 

There should be a lot for sale in the marketplace. If not eBay is your best bet or rock auto

 

OEM coilpacks are made by Hitachi (Part# IGC0007). Sometimes you can find them cheaper listed this way rather than buying them out of a Nissan box.