Weird thing happened today - Need help!

[Haywood]

Of course this happens when I'm 3 hours from my house and there's snowstorms all over the place!

Went to visit my daughter at school. Get in the car, start it up and the engine malfunction light comes on. Reduced power. RPM's limited to 4k. The car is rumbling and it noticeable louder. There isn't a BMW near where I am, so I find an AAMCO just so they can take a look at it. If you see a list of my mods, I installed the straight pipes myself some 4 months with no issues. So, originally I thought they came loose and it was losing back pressure. I also installed the intake and again haven't had any issues.

After they inspected the x-pipe and exhaust, they found no leaks and no issues with the clamps. (I went under the lift to look as well). The guy then ran a scan with an ODB tool and it came up as cyl 5,6,7,8 were all misfiring. Here are the codes if anyone can make sense of them.

P0300 Random/Multiple Cylinder Misfire Detected
P0305 Cylinder 5 Misfire Detected
P0306 Cylinder 6 Misfire Detected
P0307 Cylinder 7 Misfire Detected
P0308 Cylinder 8 Misfire Detected

It was too late to get to a dealership, so I got a hotel. Ironically, as I was driving to the hotel, the issue went away! I didn't chance driving home so I will stop on the dealership tomorrow to have them check it out.

Does anyone have an idea why this happened and then why it just went away?

Thanks in advance.

[SYZ]

might be that one of the o2 sensors was on the fritz.

[BPMSport]

Throttle actuator cyl 5-8

[Time Lord]

Originally Posted by Mike Benvo

Throttle actuator cyl 5-8

so is his going out?

Also OP i would suggest to keep a 10$ bluetooth ob2 scanner in your car just incase next time to read codes. i have one if you need it....

[Petros]

You need to rescan it with a scanner compatible with the MSS60 ECU. This will tell you the BMW-specific error codes possbily stored. It can tell you if the actuator is bad or not

[Lerxst M4]

Originally Posted by Mike Benvo

Throttle actuator cyl 5-8

Agreed...same thing mine did when mine went out as well. I was also with my daughter and it actually stranded us.

Have you broken the 60K mile threshold yet? Mine is an 08 and I had both banks fail between 61K and 62.5K miles.

Thankfully I am CPO!

[BPMSport]

Originally Posted by Lerxst M3

Agreed...same thing mine did when mine went out as well. I was also with my daughter and it actually stranded us.

Have you broken the 60K mile threshold yet? Mine is an 08 and I had both banks fail between 61K and 62.5K miles.

Thankfully I am CPO!

Mine failed at about 52K - so I had both replaced knowing that replacing one would just lead to another headache within 10k miles.

[Haywood]

Thanks, guys. I was able to get home without any issues. It's strange how it just went away. I will be taking it to my dealer this weekend for testing.

[Enforcer]

Any update? I've experience the exact same thing and I only have 16k on the clock.

[Groundpilot]

Is there any way to check the condition of throttle actuator?
I would really hate to get stranded.

[Petros]

Yes. Remove the intake manifold. Have someone turn the ignition to ON without starting the car (so no clutch or brake pressing). The ECU will conduct a test cycle on the actuators. They will cycle from closed to open and back to closed again. if an actuator doesn't fully open, or gets stuck in the open position and doesn't close, then you know it's faulty. But if you already have the error codes for the actuator then there's a good chance it's faulty anyway.

[Haywood]

Originally Posted by Enforcer

Any update? I've experience the exact same thing and I only have 16k on the clock.

So, here's the update. Took it to the dealer. They, of course, are stating that since I have removed the front cats, this is the reason for the error. Unless I bring the car back stock, they can't look at anything else.

Thanks to Mike B, we've analyzed the codes and feel that it's definitely not related to the cat removal. Throttle actuator or idle control valve. I'm only having it go into limp mode at startup or low RPM's. The issue has gotten worse everyday. I'm hoping to install another OEM x-pipe this weekend and then bring it back to the dealer. I'll keep you guys posted.

[M3ANMACHINE]

Friend of mine had this exact same issue and it ended up being his "idle strips" I believe they were called. He replaced them and the car ran perfectly afterwards.