[sick_112290]

Hey ppl...I have an 07 335i sedan...my car started misfiring and code came up as p0300, p0301, p0302, and p0303...I changed out all 6 plugs and coils and ran fine for a couple of days...then misfire again wit all 3 cylinders again...so I changed out 3 injectors and coded them with inpa and ran fine for like a week..and now it misfired again and codes are the same cylinder 1, 2, and 3...so do u guys think it's a bad o2?? Idk wat to do......wat u guys think??
Thanx for the help...

[theweebabySeamus]

O2 sensor, there's one for cyl 1,2,3 and another for cyl 4,5,6.

[sick_112290]

Yea that's wat I was thinking too but idk cuz it didn't throw no o2 sensor code...but that next...and the o2 I gotta change is bank 1 sensor 1 right?? Or do I gotta replace both bank 1 s1 and bank1 s2?

[Beans562]

take out your dme and test your mosfets. they may have failed.

[teoanne2527]

Same thing it happened to my car last 2 moths. I purchase 6 new ignition coil but my friend told me it could be bad fuel so I bought one bottle of techron fuel injector cleaner and miss fire neve came back. Never got a chance to install all new coil.

[sick_112290]

Damn really?? Ima try that now and see wat happens...and it only misfires when it's cold....but thanx for the help...

[sick_112290]

Damn I still can't figure this mysterious misfire....it only misfires when it's cold...and then it runs fine...any suggestions ppl?? Plz and thanx u...

[sick_112290]

See that's wat I was thinking...I wanted to change out the o2 sensor for bank1 but wasn't sure since no code comes up...when I load inpa bank 1 and bank 2 o2 read good....or wat do they need to read at??

[alpin3d3vil335]

Swap your bank 1 sensor to bank 2 and see if the misfire follows the bank.

You will have to drape the sensor lead across the engine in order for it to reach due to the leads being different lengths.

If the misfires jump to 4,5,6 then its safe to say its the 02

Originally Posted by sick_112290

Damn I still can't figure this mysterious misfire....it only misfires when it's cold...and then it runs fine...any suggestions ppl?? Plz and thanx u...

what ended up fixing the misfire for you ? it sounds like the exact same thing just started happening to me. im not sure what the codes were because i cleared them before i looked at them, but ill check if they come back later today. misfire cylinder 1,2,3 only until the car is at about 20 degrees celcius and then it runs perfectly fine. really hopeing its not injectors

[Marct2009]

I'm having the same exact issue as described. I started with replacing cylinder 2 and 3's ignition coils considering the sparks are still fairly new. Still the same issue. So I replaced the bank 1 sensor 1 o2 sensor yesterday and I still have the same issue. I'm going to give the fuel injector cleaner a good try. I'll report within a week if I have any good results.

[dane_c21]

Hey guys, before I start, yes I've done what I can to search other threads for a solution so if anyone finds a relevant thread, shoot me the link lol

Okay, now that's outta the way, I've got a misfire, rough idle at times, no power once the code rethrows itself after starting the car again. and a CEL of course, that I've had scanned. Its giving me error codes p0300, p0301, p0302 and p0303 for a misfire on cylinder 1,2,3, an error for a "random misfire", and also codes 10700,10701,1072, and 10703.

I've replaced all 6 spark plugs with NGK iridium plugs, I've replaced all 6 coil packs, I've replaced the crankshaft sensor, and also both the intake and exhaust camshaft sensors. I've erased the codes but then CEL comes back within 1 minute of driving.

Someone please help me.

[tello2020]

Hello any one found the solution of this
I have the same problem with my car
2007 bmw 335i misfiring cylinders 1 2 3
Thanks