Turbos causing misfires (I think)

[jlagarde1]

This has happened twice with my 2013 550i.

First time I floored the throttle (which I never do) and I'm assuming the turbos are cranking up and the car immediately ran rough and had to limp home. Found I had PO305 misfire. I let it sit a day or so without improvement. Replaced 5th cylinder plug and it ran fine.

Second time last week, about 3 months after 1st episode, (driving home from Thanksgiving vacation), I again floored the throttle and immediately the engine lost power and ran really rough. Had to limp to the exit and get it towed 200 miles. Errors were cylinders 1, 4 and 5 had permanent misfires. I just replaced all the plugs and coils yesterday (mileage is about 65k) and it seems to run fine.

Can someone help me understand what's happening here? Were my plugs and/or coils just in weakend condition or is there something else going on? Car always runs fine and I just don't have the need for speed so flooring the throttle is not a part of my driving pattern. Thanks for any help or insight you can offer.

[bmwdirtracer]

Welcome to the forum.

How many miles on the car?

The spark plugs need to be replaced every 50k miles.

This is a high-maintenance car. As a rule, you should be spending about $2500 a year in maintenance and repairs on this car - years this wasn't done accrue... so you may owe your car MANY thousands of dollars. How many times has the transmission been serviced? Have you been flushing the brake fluid every 2 years? How's your antifreeze ? (It lasts about 4 years, then starts eating the engine.)

P-codes are useless for diagnosing a BMW - they are emissions codes. You need to be reading BMW manufacturer diagnostic codes with a BMW capable scan tool. You'll likely find other codes which will help to diag your misfires. Turbos don't cause misfires.

I'd highly recommend finding a BMW specialist independent shop and ask them to look over your car for needed maintenance and repairs. Tell them about your misfire experiences too.

By the way, this is the most troublesome, least reliable engine BMW's ever made. Google "N-63 problems".

[jlagarde1]

Hi Chris, I didn't phrase the question correctly. I don't think the turbos are the cause, I just don't understand the correlation between the two events and what was the cause. I have maintained the car, brake fluid, antifreeze, oil etc. and a new tranny installed about 3 years ago. Car runs fine all the time.

I'm just wondering what happens when I want quick acceleration and increased speed if some freaky condition during combustion could cause a plug to fail because that's what happens. Changing plugs fixes the issue. Maybe injector or timing. Maybe the plugs were just failing.

Thanks again