Misfiring - Only one bank?

[douglee25]

What are the possible causes for misfiring on ONLY one bank of cylinders (cylinders 5-8)?

Pulling codes has only told me the cylinders are misfiring (duh) but hasn't pulled anything to help isolate the cause.

Thanks.

[Haywood]

Originally Posted by douglee25

What are the possible causes for misfiring on ONLY one bank of cylinders (cylinders 5-8)?

Pulling codes has only told me the cylinders are misfiring (duh) but hasn't pulled anything to help isolate the cause.

Thanks.

Here's the codes I was getting.

http://www.m3post.com/forums/showthread.php?t=1158519

You also look up the codes here:

http://www.bmwforums.info/bmw-electr...es-list-3.html

[douglee25]

OK so did the O2 fix it?

I've replaced it once about 3k miles or less ago.

[Haywood]

Well, I thought it did. Wasn't haven't any problems, but now it's back. I haven't replaced another sensor (they are ridiculously priced now and hard to find) so I've been slowly going back to stock to see what is causing it.

[douglee25]

Ok well I'm still stuck....

Anyone else care to chime in?

[douglee25]

Anyone?

Is this mic on?

Edit -

Yesterday the car went through 4-5 drive cycles without one misfire or code. Then late last night it started again just idling in a parking lot. Misfired on cylinders 5-8 and an O2 code on deceleration.

Need some help!

Thanks.

[Haywood]

Originally Posted by douglee25

Anyone?

Is this mic on?

Edit -

Yesterday the car went through 4-5 drive cycles without one misfire or code. Then late last night it started again just idling in a parking lot. Misfired on cylinders 5-8 and an O2 code on deceleration.

Need some help!

Thanks.

Re-seated and swapped bank 1 and bank 2 sensors. So far so good. Cleared codes and haven't gone into limp mode. FYI, the only time this happens is at idle. I'll report back if I still have a problem, but I think it's your O2 sensors.

[douglee25]

Originally Posted by Haywood

Re-seated and swapped bank 1 and bank 2 sensors. So far so good. Cleared codes and haven't gone into limp mode. FYI, the only time this happens is at idle. I'll report back if I still have a problem, but I think it's your O2 sensors.

Interesting.

For what it's worth, last night I swapped back in the O2 on bank 2 that was new as of March/April 2015. For reference the one that was in today on bank 2 was the old one from bank 1. Bank 1 never threw a code previously so I figured it would be fine. That O2 has been in the car on bank 2 since June 2015 or so? I swapped them back in June (new for old) because I was still getting some random O2 codes on bank 2 and I wanted to see if the swap would fixed it. The newer O2 sensor on bank 2 never gave me misfires though, only some random codes.

We will see what happens.

[douglee25]

Update 9/1/15 - 6 days after putting an older O2 back in on bank 2....

I haven't had one misfire or engine code. I will continue to monitor things and see if that is really the cause.

I was not under the impression that O2's could cause misfires? Engine codes, yes. Misfires, no?

Has anyone else seen that?

[douglee25]

Update 9/23/15 -

I've been running for 4 weeks now with the old O2 sensor and zero codes or misfires.

I think I can positively state that the issue was with the O2 causing the misfires.

And for the record, the throttle actuator never did show up during my code scans.

[atopa2002]

also test your alternator, same thing happened to me, the "rough idle and bam limp node on hot day "
dealer says the alternator is not charging, change it and its good so far

[Haywood]

Glad things are better. Just had a horrible day again the other day. Car was going into limp mode and almost couldn't the car home. Pulled codes and the same errors. VKAT Bank 2. Fortunately, I had bought a used one from a member. Changed it out and all is better. I just don't understand why this sensor keeps going bad.

[douglee25]

Very odd man.

Keep us posted.

Doug

[monkishor]

douglee25 ,
i have exactly the same symptoms as you: car getting into limp mode, either while idling or while going really slow.

have you concluded in the end that the O2 sensor fixed your issue ? I am only getting misfires on 5-8 with shutdown of the whole bank. no other codes come up, so I am a bit confused as to why it would not just mention that there is a faulty O2 sensor, or O2 sensor reading....

i have swapped the throttle actuator between banks and the error stayed on the same cylinders.

[Yoddha]

Originally Posted by monkishor

douglee25 ,
i have exactly the same symptoms as you: car getting into limp mode, either while idling or while going really slow.

have you concluded in the end that the O2 sensor fixed your issue ? I am only getting misfires on 5-8 with shutdown of the whole bank. no other codes come up, so I am a bit confused as to why it would not just mention that there is a faulty O2 sensor, or O2 sensor reading....

i have swapped the throttle actuator between banks and the error stayed on the same cylinders.

Have you guys figured this out? I am having the same exact symptoms and I've replaced my O2 sensors twice and replaced both throttle actuators two days ago.

Car went into limp mode today yet again with only the Bank 2 cylinders misfiring. I also keep getting this 27B1 (secondary air system throughput bank 2) 275E (lambda control stop error bank 2) or 2751 (lambda probe error pump current line before kat bank 2)

[monkishor]

Originally Posted by M__3__R__A__G__E

Have you guys figured this out? I am having the same exact symptoms and I've replaced my O2 sensors twice and replaced both throttle actuators two days ago.

Car went into limp mode today yet again with only the Bank 2 cylinders misfiring. I also keep getting this 27B1 (secondary air system throughput bank 2) 275E (lambda control stop error bank 2) or 2751 (lambda probe error pump current line before kat bank 2)

After I have exchanged the TAs between themselves, the error stayed on the same bank... eliminating the TA as the potential problem.

I have narrowed it down (i hope) to an exhaust leak on the left side, which I believe is just before the o2 sensor.
exhaust sounds like a hemi v8 at idle and sounds like it has a hole in the exhaust when driving it through a tunnel. it would make sense because its only going in limp mode when at low rpm, as I believe the low pressure in the exhaust allows it to suck in false air and sends the o2 sensor the wrong values. when reving it hard, the gas just goes out, so the o2 sensors are getting the right reading.

i have ordered the gasket, which apparently is known to fail, but did not have time to change it.
will let you know if that is the case. hope
its not a hole in the exhaust 😂

[Yoddha]

Originally Posted by monkishor

After I have exchanged the TAs between themselves, the error stayed on the same bank... eliminating the TA as the potential problem.

I have narrowed it down (i hope) to an exhaust leak on the left side, which I believe is just before the o2 sensor.
exhaust sounds like a hemi v8 at idle and sounds like it has a hole in the exhaust when driving it through a tunnel. it would make sense because its only going in limp mode when at low rpm, as I believe the low pressure in the exhaust allows it to suck in false air and sends the o2 sensor the wrong values. when reving it hard, the gas just goes out, so the o2 sensors are getting the right reading.

i have ordered the gasket, which apparently is known to fail, but did not have time to change it.
will let you know if that is the case. hope
its not a hole in the exhaust 😂

I'm thinking the same thing. Fingers crossed 😂

[omgzirra_exe]

take a pic of your O2 sensor and post it. i want to see how they look

[monkishor]

Originally Posted by omgzirra_exe

take a pic of your O2 sensor and post it. i want to see how they look

just finished the repair...
when we got under the car and took off the exhaust we realised that there was no gasket on the left hand side...

after we put the oem gasket on and changed the one on the right side, the car has changed COMPLETELY. the sound is now smooth and linear... absolutely no more trembling when idling and the car now idles straight at 600rpm.
before there was a small fluctuation and it was always idling around 7-800rpm.

it all makes sense now... because probably the o2 sensor was getting a wrong reading and therefore was chocking the engine at idle, causing the "broken exhaust" sound, skaing and fluctuating idle.
I can now say that the problem was for sure coming from this.

i am absolutely shocked by how the engine runs now...

sorry I did not take a picture of the O2 sensor because we did not take it off. only took off the bolts from the exhaust and that allowed us to put in the new gasket without having to take off the exhaust.

we literally did this on the side of the road and it took us around 1 hour in total. (it actually took us more time to put back the cover from underneath the engine than to actually change the gaskets)

[omgzirra_exe]

Originally Posted by monkishor

just finished the repair...
when we got under the car and took off the exhaust we realised that there was no gasket on the left hand side...

after we put the oem gasket on and changed the one on the right side, the car has changed COMPLETELY. the sound is now smooth and linear... absolutely no more trembling when idling and the car now idles straight at 600rpm.
before there was a small fluctuation and it was always idling around 7-800rpm.

it all makes sense now... because probably the o2 sensor was getting a wrong reading and therefore was chocking the engine at idle, causing the "broken exhaust" sound, skaing and fluctuating idle.
I can now say that the problem was for sure coming from this.

i am absolutely shocked by how the engine runs now...

sorry I did not take a picture of the O2 sensor because we did not take it off. only took off the bolts from the exhaust and that allowed us to put in the new gasket without having to take off the exhaust.

we literally did this on the side of the road and it took us around 1 hour in total. (it actually took us more time to put back the cover from underneath the engine than to actually change the gaskets)

i had a feeling it was o2 sensor related but it was more of a gasket thing. i forget that the donut gasket is prone to failure easily. so glad it was a cheap fix!

[meickel]

The plugs where the Pre Kat O2 sensors are plugged in, are often slightly corroded or wobbly.

They must always be properly tightened

Clean with contact spray then with a small needle something in it scratch/clean and with 2-3 cable ties, for testing, the plugs tightly together so that they hold together even at high Revs or start and always have contact.

This connection often causes mysterious, but not exclusively, O2 error messages.

[smokinjoe64]

Originally Posted by douglee25

What are the possible causes for misfiring on ONLY one bank of cylinders (cylinders 5-8)?

Pulling codes has only told me the cylinders are misfiring (duh) but hasn't pulled anything to help isolate the cause.

Thanks.

Same issue a month ago.
Replaced #8 coil [would have done all but no aftermarket inventory nationally]
Replaced RT bank plugs.
Running great now.