Code P0300

dts3 · 06-03-2019, 03:11 PM

Quote:

Originally Posted by Cyber370

P0300 means you have a random misfire not related to just one cylinder. If it was just one cylinder it would give you P0301 for cylinder one, P0302 for cylinder two and so on ...

Does this mean that all P0300 codes started off life as a specific code (P0301 etc...) that was later converted into P0300 when multiple coils were misfiring (assuming the P0300 is an actual misfire)?

YEG370z · 06-21-2019, 11:35 PM

Hi guys, I'm new here and I'm having same problem.
I bought the 2010 370z roadster last year, very low mileage with only 25,000 km (not miles).
It has same mod as well. Stillen cold air intake and exhaust system (love the sound).
I drove it for about 4k then I get the P0300 code one day randomly. I reset it and didn't get it for a week then it pops back. I talked to a mechanic and he said the same thing that it could be many reasons and I might want to start with the small ones first. He said it might be "bad" gas so I drive until the gas as low as it could then I fill up with a different station and reset the code. It went a full tank with no lights, so I thought I have figured it out. I refilled same station and a few days later same problem. I cleaned the TB and MAF but same thing after a week.
I saw somewhere that it could be vacuum leak and I tested that as well with no issues.

Someone in this thread mentioned it could be vibration. This could be the issue too, when idling I do noticed sometime the engine make a slight vibration that does feel like a misfire because when it does that vibration i noticed a little twitch in the RPM.

Any ideas guys? I am about to order spark plugs to change.

Sent from my SM-N950W using Tapatalk

Nikolai.z34 · 06-22-2019, 05:54 PM

Quote:

Originally Posted by YEG370z

Hi guys, I'm new here and I'm having same problem.
I bought the 2010 370z roadster last year, very low mileage with only 25,000 km (not miles).
It has same mod as well. Stillen cold air intake and exhaust system (love the sound).
I drove it for about 4k then I get the P0300 code one day randomly. I reset it and didn't get it for a week then it pops back. I talked to a mechanic and he said the same thing that it could be many reasons and I might want to start with the small ones first. He said it might be "bad" gas so I drive until the gas as low as it could then I fill up with a different station and reset the code. It went a full tank with no lights, so I thought I have figured it out. I refilled same station and a few days later same problem. I cleaned the TB and MAF but same thing after a week.
I saw somewhere that it could be vacuum leak and I tested that as well with no issues.

Someone in this thread mentioned it could be vibration. This could be the issue too, when idling I do noticed sometime the engine make a slight vibration that does feel like a misfire because when it does that vibration i noticed a little twitch in the RPM.

Any ideas guys? I am about to order spark plugs to change.

Sent from my SM-N950W using Tapatalk

Hi and welcome to the club

) P0300 is most annoying code I`ve ever seen.
At first dont throw your money randomly to change the parts, buy cheap obd reader and try to shrink the area of search, could be very useful.
Compare maf voltages, injectors duty time, o2 sensors output for both banks 1 and 2.

What I did with no effect:
TB, MAF and MAP cleaning
New spark plugs
Intake vacuum leak test
Fuel injectors test

Than found that MAF voltage for the bank 1 and injectors duty time are higher, also primary O2 sensor readings is different from bank 2.

Finally:
Welding of all joints of exhaust manifolds and cats
new exhaust gaskets everywhere
new primary o2 sensor bank 1
and may be the real reason of a misfire - bank 1 maf tube was so overtighted by the clamp that it was actually squashed. So less maf tube diameter - wrong readings. Bought and installed new maf tubes.

Problem solved.

PS: check the oil pressure, probably its a broken gallery gasket.

JSON · 01-24-2021, 01:21 AM

Quote:

Originally Posted by Josies370z

hey guys

any updates on this? i recently starting throwing the same code. 2010 370z 70000 miles with berk hfc, stillen G3, and nismo exhaust with a Ecutek tune are the only mods currently. Clutch/flywheel replaced at approx 50,000 (CSC failed, tune and clutch/flywheel done at Specialty Z). It was running fine until about a week ago when it threw a code. idle is slightly rough but seems to run ok but i can tell its slightly off. check engine flashes and remains on and at one point would flash and disappear but now its just on all the time. changed the spark plugs with oem plugs, cleaned both TB's, didnt make a difference. My next moves are to clean the MAF's and re-inspect the plugs. Guy at the auto store said to check the gaps of the plugs and the coil connections that they may not be making good contact and recommended the contact gel they have, i wasnt sold on the 2 things he mentioned as im assuming the plugs would be pretty accurate from the dealer, possibly the coils but would be a hard to determine. Dont know where to go from there so im looking for any input?? thanks!!

Sounds like my issue. Any updates on fixing this?

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06-21-2019, 11:35 PM	#32 (permalink)
YEG370z Base Member Join Date: May 2018 Location: Alberta Posts: 1 Drives: 2010 370z Roadsters Rep Power: 7	Hi guys, I'm new here and I'm having same problem. I bought the 2010 370z roadster last year, very low mileage with only 25,000 km (not miles). It has same mod as well. Stillen cold air intake and exhaust system (love the sound). I drove it for about 4k then I get the P0300 code one day randomly. I reset it and didn't get it for a week then it pops back. I talked to a mechanic and he said the same thing that it could be many reasons and I might want to start with the small ones first. He said it might be "bad" gas so I drive until the gas as low as it could then I fill up with a different station and reset the code. It went a full tank with no lights, so I thought I have figured it out. I refilled same station and a few days later same problem. I cleaned the TB and MAF but same thing after a week. I saw somewhere that it could be vacuum leak and I tested that as well with no issues. Someone in this thread mentioned it could be vibration. This could be the issue too, when idling I do noticed sometime the engine make a slight vibration that does feel like a misfire because when it does that vibration i noticed a little twitch in the RPM. Any ideas guys? I am about to order spark plugs to change. Sent from my SM-N950W using Tapatalk