P0300 random misfire code HELP!

Alchemy · 04-28-2011, 12:50 PM

Hey guys heres the story, I got a p0300 code last fall, cleared it w my friends computer and it came back a few weeks later. I stored it for the winter, code was still there when I put it back on the road the other day. I scheduled a dealer service for today and of course the light went off 2 mi from the dealership!! Wtf! Anyone know why this would happen?? I have a bunch of parts waiting to go on my car but I want this fixed first so I dont have to worry bout voiding the warranty. Thanks.

ChrisSlicks · 04-28-2011, 01:17 PM

It happened to my car after sitting for the Winter. I think the fuel trims were all messed up after sitting for so long, but once it was idling for a while it seemed fine so I just reset the code and it hasn't come back.

Is your car still stock?

Alchemy · 04-28-2011, 01:56 PM

Quote:

Originally Posted by ChrisSlicks

It happened to my car after sitting for the Winter. I think the fuel trims were all messed up after sitting for so long, but once it was idling for a while it seemed fine so I just reset the code and it hasn't come back.

Is your car still stock?

Still stock. I was getting the code before I took it off the road. Had it for a few weeks back in the fall, cleared it and it came back. I drove it for a few more weeks w it on before it went off the road for the winter.

ChrisSlicks · 04-28-2011, 02:01 PM

It is possible the AF ratios are a little bit out of whack. I've seen this happen a couple of times even on stock cars.

But first make sure you're using good quality gas, the 370Z is pretty picky and throws a tizzy if you give it the cheap stuff.

6MT · 04-28-2011, 03:58 PM

Quote:

Originally Posted by ChrisSlicks

It is possible the AF ratios are a little bit out of whack. I've seen this happen a couple of times even on stock cars.

But first make sure you're using good quality gas, the 370Z is pretty picky and throws a tizzy if you give it the cheap stuff.

Alchemy · 04-28-2011, 05:55 PM

Quote:

Originally Posted by 6MT

Well hopefully thats it. What really confuses me is the fact that it was on for so long then went off. I was almost on empty when I gassed it up yesterday and the light went off today which makes it seem like it could be a fuel issue. But, I filled it up plenty of times when the light was on last fall and it never went off then.

ChrisSlicks · 04-28-2011, 06:00 PM

Quote:

Originally Posted by Alchemy

Well hopefully thats it. What really confuses me is the fact that it was on for so long then went off. I was almost on empty when I gassed it up yesterday and the light went off today which makes it seem like it could be a fuel issue. But, I filled it up plenty of times when the light was on last fall and it never went off then.

The light goes off when it hasn't seen a misfire for a given number of cycles and time. If they continue to occur sporadically then the code stays active.

It can also be caused by the primary O2 sensors giving bad feedback data, but this mainly occurs in high mileage vehicles.

Alchemy · 04-28-2011, 06:58 PM

Quote:

Originally Posted by ChrisSlicks

The light goes off when it hasn't seen a misfire for a given number of cycles and time. If they continue to occur sporadically then the code stays active.

It can also be caused by the primary O2 sensors giving bad feedback data, but this mainly occurs in high mileage vehicles.

I was wondering yesterday about the cycles. How long does it take to run completely through a cycle on a 370? Btw thanks for the help rep^.

ChrisSlicks · 04-28-2011, 08:54 PM

Quote:

Originally Posted by Alchemy

I was wondering yesterday about the cycles. How long does it take to run completely through a cycle on a 370? Btw thanks for the help rep^.

I'm not sure of their exact formula, but they usually stick for about 3-4 starts and/or 30-50 miles.

djpathfinder · 04-28-2011, 10:12 PM

I also got the same code shortly after nearly stalling while on a steep hill. Cleared the code and hasn't happened again.

Alchemy · 04-28-2011, 11:07 PM

Quote:

Originally Posted by djpathfinder

I also got the same code shortly after nearly stalling while on a steep hill. Cleared the code and hasn't happened again.

My biggest concern is the fact that I have cleared it and it returned. I really wanted to feel comfortable about the running condition before I screw up my warranty by putting my Stillen CBE & Gen 3 on. Gonna have to say to hell with it though, I cant look at these parts any longer, they have been here for months. Installing myself saturday

Cant wait to hear her new growl.

pulpz · 05-07-2011, 06:15 PM

MIL is on and Just diagnosed mine today. P0300. going to reset, run out this tank of gas, and make sure i refill on quality gas and see how it goes. Will keep posted.

blacknismoZ · 12-02-2011, 06:34 PM

any update? after parking my car for 1 week the check engine light is on due to misfire. took it to dealer and they said might be low voltage??

04-28-2011, 12:50 PM	#1 (permalink)
Alchemy A True Z Fanatic Join Date: Jan 2009 Location: Jersey Age: 45 Posts: 4,855 Drives: to acquire tickets Rep Power: 3525	P0300 random misfire code HELP! Hey guys heres the story, I got a p0300 code last fall, cleared it w my friends computer and it came back a few weeks later. I stored it for the winter, code was still there when I put it back on the road the other day. I scheduled a dealer service for today and of course the light went off 2 mi from the dealership!! Wtf! Anyone know why this would happen?? I have a bunch of parts waiting to go on my car but I want this fixed first so I dont have to worry bout voiding the warranty. Thanks. __________________ Ryan 314WHP \| 260LB-FT \| STILLEN \| KONI \| SWIFT \| STOPTECH \| Z1 \| PROJECT MU \| CNT \| UPREV \| FORGESTAR \| BRIDGESTONE \| PWJDM \| ENEOS \| MOTUL

04-28-2011, 01:17 PM	#2 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 653	It happened to my car after sitting for the Winter. I think the fuel trims were all messed up after sitting for so long, but once it was idling for a while it seemed fine so I just reset the code and it hasn't come back. Is your car still stock? __________________ Hotchkis ARB \| Stillen CAI \| Art Pipes \| Berk CBE \| Stillen AP Racing Brakes \| AE Performance Oil Cooler \| BC Racing ER Coilovers \| Doran Control Arms

04-28-2011, 02:01 PM	#4 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 653	It is possible the AF ratios are a little bit out of whack. I've seen this happen a couple of times even on stock cars. But first make sure you're using good quality gas, the 370Z is pretty picky and throws a tizzy if you give it the cheap stuff. __________________ Hotchkis ARB \| Stillen CAI \| Art Pipes \| Berk CBE \| Stillen AP Racing Brakes \| AE Performance Oil Cooler \| BC Racing ER Coilovers \| Doran Control Arms

04-28-2011, 10:12 PM	#10 (permalink)
djpathfinder A True Z Fanatic Join Date: Mar 2010 Location: Edmonton, Canada Posts: 12,910 Drives: 2012 GT-R BE Rep Power: 733	I also got the same code shortly after nearly stalling while on a steep hill. Cleared the code and hasn't happened again. __________________ 2012 GT-R Black Edition Jet Black 2010 370Z 40th Anniversary // SOLD

05-07-2011, 06:15 PM	#12 (permalink)
pulpz Enthusiast Member Join Date: May 2009 Location: Dayton, Ohio Posts: 281 Drives: 09 PG 370Z Sport 6MT Rep Power: 16	MIL is on and Just diagnosed mine today. P0300. going to reset, run out this tank of gas, and make sure i refill on quality gas and see how it goes. Will keep posted. __________________ 2016 Cayman GTS 6MT / 2017 Q60 Sport / 2012 Acura TL SH-AWD / 2015 Lexus IS 350 AWD F-Sport (Sold) / 2009 PG 370Z Sport 6MT, (Sold) / 2003 SS 350Z Enthusiast 6MT (Sold)

12-02-2011, 06:34 PM	#13 (permalink)
blacknismoZ Base Member Join Date: Mar 2010 Location: PDX Posts: 166 Drives: 2010 370Z NISMO Rep Power: 15	any update? after parking my car for 1 week the check engine light is on due to misfire. took it to dealer and they said might be low voltage?? __________________ HKS filter, DBA 5000/4000, HPS, Stoptech. bone stock dyno at Surgeline tuning 294whp 251tq.

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