Help - Multiple Cylinder Misfire's

[Justinhab]

Yesterday I started my 2008 M3 after it had been sitting for about a week. It cycled through the cold start and everything seemed fine. Once I drove it for about a mile I received the "Engine Malfunction/Reduce Power" message and it started idling very rough. I drove it back home and checked the codes. Cylinder's 1, 2, 3, 4, 5, 6 and 7 were all misfiring. The 8th cylinder was the only one not misfiring.

I let the car sit overnight and started it this morning. Im still receiving the engine malfunction message, however now only Cylinders 1, 2, 3, 4, 5 and 6 are misfiring. 7 and 8 are not.

I know typically misfires can be a combination of coils and plugs but it would seem odd for all of these to go out at once. Plus it seems strange that cylinder 7 was misfiring yesterday and now it's not today.

Im just wondering if anyone has experience this or have an idea on what to start testing first. By the way my car only has 40,000 miles.

Thanks!

[m3toboot]

First read the codes so you know what the car is complaining about.

[Mvy]

Code check will likely push you towards coils is my guess. This does not seem the same as TA issues Ive read about but that is always a possibility.

[BPMSport]

Likely not coils.

Since it's affecting almost all cylinders it's probably the idle control valve.

[Justinhab]

Here are the current codes. I've received multiple cylinder misfire codes that keep changing, I don't receive the same cylinder misfire each time. For example I may get misfire's on cylinders 2, 3, 5 and 7. Then I'll clear the codes and test it again but next I'll get misfire's on 3, 4, 5, 6 and 8. I've basically received misfire codes on each cylinder but at different times.

P0300 Random Multiple Cylinder Misfire
P0302 Cylinder 2 Misfire
P0303 Cylinder 3 Misfire
P0304 Cylinder 4 Misfire
P0305 Cylinder 5 Misfire
P0306 Cylinder 6 Misfire
P0174 System Too Rich Bank 2

I only received the P0174 once and then it went away. Today I swapped the pre-cat o2 sensors from bank 1 and 2 but it didn't change anything.

I wouldn't think this would be an issue with the plugs, coils or throttle actuators since Im receiving multiple misfires through each bank.

[Justinhab]

Originally Posted by Mike Benvo

Likely not coils.

Since it's affecting almost all cylinders it's probably the idle control valve.

Thanks Mike. Would a bad idle control valve put the car into limp mode?

[BPMSport]

Originally Posted by Justinhab

Thanks Mike. Would a bad idle control valve put the car into limp mode?

Absolutely.

[8600RPM]

This is O2 sensor, classic
Mike why would you think Icv over O2? Am I missing something?

[BPMSport]

Originally Posted by 8600RPM

This is O2 sensor, classic
Mike why would you think Icv over O2? Am I missing something?

Could be either, or something else.

[Justinhab]

So I finally had to tow the car into BMW. After 4 hours of diagnostics they still couldn't determine an issue. They finally determined that 3 plugs were foaled (I love this took them 4 hours). They wanted to change the plugs and do a compression and leakdown test. I'm already into this $500 for the diagnostic, now I'm looking at another $800 for plugs and a compression and leakdown test. Even though I hate paying for things I can do myself I'm kinda stuck so I tell them to move forward.

They do a compression test and determine there's no compression in cylinder 4. They suspect it's a bad valve spring. After removing the valve cover they're now telling me I have a bent valve. The total repair cost will be $10,500 assuming there are no other issues. I almost had a F-ing heart attack!

This car has been babied since new. It's never been ran hard and always well cared for. I can't believe this would happen with only 40,000 miles. I haven't found anyone that has had any valve issues with these motors. Typically bent valves are due to timing issues or high revs, which neither of those were a factor in my case Has anyone ever heard of this with these motors?

[msan]

I think other people had o2 sensor problems that threw similar codes and dealer had problems diagnosing it. Maybe get someone to replace the o2 sensors first before pluncking down $10k
http://www.m3post.com/forums/showthread.php?t=1298930

[BPMSport]

I would contact BMW NA and ask for goodwill repair.