GariepyVQ

iTrader: (1)

08 s coupe kept throwing misfire codes a while back. I changed the spark plugs and cleaned MAF sensor and throttle bodies, which seemed to fix the issue. 5000 miles later the code comes back. Only thing I notice now is my engine idles around 1000-1100 instead of 7 or 800 before the light came back, otherwise the car drives normal. Tried an ecu reset but the light just comes back, any suggestions on where I should start looking next to get rid of the code?

AG

Baadnewsburr

iTrader: (3)

If you're idling at 1000-1100 you need to do an idle relearn. Its kind of tricky and may require several attempts but once you get the hang of it...its still tricky :P , but very doable ....or you can go to a dealer and have them do it. there is a very long DIY therad on here shouwing exactly how to do it.

see post #6 in this tread or just google g37 idle relearn

https://www.myg37.com/forums/engine-...eaning-tb.html

GariepyVQ

iTrader: (1)

Seems like the same procedure as the ECU reset, I'll try it again tonight and maybe it'll work for me this time.

GariepyVQ

iTrader: (1)

Thanks I'll try that out, shouldn't cost much regardless since it's on the tsb right? Plus it doesn't seem too labor intensive on their part.

ILM-NC G37S

iTrader: (3)

Keep in mind this may not be related to your original P0300 code. My car did not set any codes. I would guess it would cost around $100, any Nissan or Infiniti dealership, or quality mechanic with Nissan Consult can do this if the idle problem persists. The procedure takes less than 1 hour.

GariepyVQ

iTrader: (1)

Update: tried another ecu reset and briefly checked to make sure all plugs and hoses are properly connected, light went away. Will update if it comes back.

Baadnewsburr

iTrader: (3)

I don't remember it completely off hand, but I thought I remember that the ECU reset is only part of the idle relearn process...I thought the full idle relearn consists of:throttle position reset, ecu reset and idle relearn.

If your idle remains above 1000 RPM the problems not gone you may just be used to the high idle... if its back below 800 then good news problem should be solved...I'm hoping for the latter for your sake, good luck.

soundkillr

In most cases if you throw a p0300 the ecu will hold idle higher than normal. Once you reset the code, idle will return to normal.

GariepyVQ

iTrader: (1)

Yeah luckily it's back down to normal, hopefully it stays that way. If it comes back I'll try to find more info on a full idle relearn process

Baadnewsburr

iTrader: (3)

good to hear man!

GariepyVQ

iTrader: (1)

So now it's getting weird. Started having the light come on more frequently over the past couple weeks. Pretty much only comes on after a cold start, then it'll have a high idle at like 1000-1200 rpm, once it warms up, I reset the ecu and it's normal again. Been trying to get it diagnosed but I just haven't had the time so I keep doing the ecu/idle reset just so it drives normal until I can get it fully checked out.

Anyways, light came on today so I did another ecu reset, only this time the idle didn't change once I started it up and stayed around 1100, but the SES light wasn't on. Then once I started driving the SES light started blinking on and off almost randomly. Seemed to flash whenever I would shift or start pushing the gas down, never stayed on, just flashed. Took a video of it on my way home, I'll figure out how to attach that in a sec. Once I got back home, I reset it again and it went back to normal. I think I accidentally went into some kind of service mode where the light flashed whenever there was a misfire? I'm not sure though, any ideas?

AG

zer099

iTrader: (2)

P0300 is your car's shotgun answer to what it "thinks" is a misfire. It could be plugs, coils, injectors, MAF, vacuum leak, or just plain hate you for bad gas. Can you actually feel if it is misfiring when you are accelerating because it sounds like it's throwing the code when you are missing during acceleration. The high idle is the car trying to compensate for what it thinks is the misfire happening at idle so it bumps up the idle, limp mode style, to keep the car running. When you reset the ECU it forgets all this then something is happening that makes it do it all again.

If you get a P030X (with X = 1 through 6) it would narrow down which cylinder the issue is. If you have no way to monitor and log, nothing to really talk to the ECU (ODB connect that is), and it's getting worse then honestly dropping the money for diagnostic might not be a bad idea.

GariepyVQ

iTrader: (1)

Didn't seem to flash the light when I was accelerating, only when I shifted or right when I started to accelerate. Like if I was just coasting in third it wouldn't flash, then as soon as I pushed down the gas it would flash then go away while I was accelerating, then flash a couple times when I release the gas and shift, then flash again once I started to accelerate. Idk it's weird, having trouble uploading the video but you'll understand what I mean once you see it. Changed plugs and cleaned MAF and throttle bodies like 10k miles ago which made it go away for a few months, and when it came back it was pretty infrequent. Never had any specific cylinder code, it's always just P0300. Kinda curious if I could get back into that "maintenance mode" after I successfully reset it and see if it keeps flashing when the engines idling normally. I think what I did was start the engine right after the ecu reset. Usually I go through the process (push the start button till the "on" lights up and go through the pedal routine) then push the button off again before I start the car, pretty sure this time I just started the car right after I finished the last step of the pedal routine which may have triggered the maintenance mode. If that makes any sense lol.