M3 Rough Idle/misfire Cylinder 1 P0301

[8600RPM]

Hence why I don't trust dealers. This took me 2 seconds to tell you it was primary o2.

Techs no longer have deductive reasoning skill. It's plug into computer and read.

Only a very small handful of things effect a bsnk of cylinders

[X5-User]

Originally Posted by 8600RPM

Hence why I don't trust dealers. This took me 2 seconds to tell you it was primary o2.

Techs no longer have deductive reasoning skill. It's plug into computer and read.

Only a very small handful of things effect a bsnk of cylinders

Just curious, how were you able to tell it is O2 sensors? Is it becase you had the same error codes before or other thing?

Also how long does the O2 sensor last if being catless?

[Brian_Fantana]

Update:

BMW just called. They said the o2 sensors seem to be doing the trick and want to keep it over night to verify that the problem is gone. No idea on what they are going to charge me yet. I'd assume $180 per sensor? Which sucks because 2 of them I wont use anymore after have BPM re-install my stage 2 tune and delete the 2 sensors behind the catalytic converter. I know you can buy Bosch o2 sensors on amazon for $80 prime shipped.

[BPMSport]

Originally Posted by Brian_Fantana

Update:

BMW just called. They said the o2 sensors seem to be doing the trick and want to keep it over night to verify that the problem is gone. No idea on what they are going to charge me yet. I'd assume $180 per sensor? Which sucks because 2 of them I wont use anymore after have BPM re-install my stage 2 tune and delete the 2 sensors behind the catalytic converter. I know you can buy Bosch o2 sensors on amazon for $80 prime shipped.

Don't replace the post cat sensors, they won't cause your issues anyway. Only the pre cat sensors can cause these issues

[dnbosiris]

thread bump
i have similar issues in my E92 M3. did this end up being just your o2 sensors?
thanks

[Brian_Fantana]

Originally Posted by dnbosiris

thread bump
i have similar issues in my E92 M3. did this end up being just your o2 sensors?
thanks

Yes, it was. Something I have noticed is my fuel economy jumped from 16mpg to about 19-20 post sensor swap. I thought it was kinda strange I was only getting 16 mpg considering I wasn't pushing the engine that much but never thought more of it.

[///Motown]

Wow, what a mess. All of this over o2 sensors!

[Scooba_Steeve]

Did you ever find a solution???

I just pulled code p0306 misfire cyl. 6.

Do you think I should replace the ignition coils and sparks ???

[go4gr8]

Thanks for the post! I'm experiencing the same thing and my car has 175k miles on it. They replaced the preCAT O2 Sensors but it's throwing the same control messages again.

Service engine soon
engine malfunction - reduced power (intermittent)

After $3k worth of work which included replacing gaskets and spark plugs, it's still doing the same things the OP has posted. Really odd noise too from the rear of the car. DMTL codes weren't thrown but it sounds like something from the fuel pump.

Revving the engine, it really sounds like it's misfiring. My dealer diagnosed that and it was supposed to be fixed.

Heading back in this coming week to see.

[kninjak]

Originally Posted by go4gr8

thanks for the post! I'm experiencing the same thing and my car has 175k miles on it. They replaced the precat o2 sensors but it's throwing the same control messages again.

Service engine soon
engine malfunction - reduced power (intermittent)

after $3k worth of work which included replacing gaskets and spark plugs, it's still doing the same things the op has posted. Really odd noise too from the rear of the car. Dmtl codes weren't thrown but it sounds like something from the fuel pump.

Revving the engine, it really sounds like it's misfiring. My dealer diagnosed that and it was supposed to be fixed.

heading back in this coming week to see.

hello reviving old thread
did you ever got a solution to your problem, i am having similar issues
thank you

[Scooba_Steeve]

Originally Posted by kninjak

hello reviving old thread
did you ever got a solution to your problem, i am having similar issues
thank you

Originally Posted by kninjak

hello reviving old thread
did you ever got a solution to your problem, i am having similar issues
thank you

Lol same.

[kninjak]

Yes no solution as it is not consistent happens once a month or so and once u restart no problem and no check engine light nothing , just stumped will drive until it The check engine lights stays on

[2011_M3]

Originally Posted by kninjak

Yes no solution as it is not consistent happens once a month or so and once u restart no problem and no check engine light nothing , just stumped will drive until it The check engine lights stays on

I know this thread is old but have you found the solution? I've heard that the o2 sensors would cause this problem.

[e92alann]

Any update since this has happened? I’m having the same issues

[go4gr8]

Sorry - I haven't been on the forum for a while.

I fixed the issue. It was a downpipe leak which no computer could have deduced. I suggested the techs to check on it and that was the culprit.