2011 328i Sudden rumbling, shuddering, and rough idle from engine with SES light

[swilli89]

Hello all!

I am a brand new BMW owner. I purchased a 2011 328i with 41k miles about a month ago. Coming from a Lexus LS and its been a really fun change! My car is the SULEV N51 variant.

I was driving to work today when all of a sudden when I came to a stop the car dropped to a lower than typical idle.. about 400-500 RPMs and sounded very rough. It was shaking the whole car although I would not say it was very violent, just very noticeable even with the radio on and the windows down. It was slightly sluggish to accelerate and while the shaking seemed to lessen at higher RPM (I limped it home and didn't want to go above 2000rpm or so) it didn't completely go away.

I have been researching as much as I can and it seems like a leading cause may be one or more of Plugs/Coils/Fuel Injectors.

I came across this thread which is how I came to register here: https://www.bimmerforums.com/forum/s...k-engine-light

With only 40k miles I definitely don't want to try and replace all 6 coils and plugs at over $200 in parts alone when I'm not even sure of the problem so I ordered this OBD sensor from amazon to see if the car will spit out a code that narrows it down to a specific cylinder. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

My car is equipped with the CIC iDrive system. Is there a way to get diagnostic codes from that interface with the use of a hidden/service menu?

Lastly, any special tools required for BMW spark plugs or are there any other ideas as to what might be going on with my car?

[MIKYZZ4]

A scan for diagnostic codes is always the first step, and also prevents any unnecessary parts purchases.
The symptoms you provided point to a possible intake leak, which is common, but let's not assume anything,
until we have had a chance to obtain and decipher the diagnostic codes.

Having a scan done helps provide the clues to a proper diagnosis. You can attempt with a generic scan tool, it may give usable results.
The preferred method is a scan performed by a BMW specific scan tool / BMW software,
as they can communicate with all BMW modules in the vehicles diagnostic system,
something a generic scan tool cannot do. In an emergency, perform with whatever tool is available.
Update us with whatever codes you discover.

A standard sparkplug socket, extension, and ratchet will do, no specialty tools required.

[cochise325]

Agree with the advice of reading codes. You can diagnose a bad coil pretty easily. The coil sits above each spark plug. A bad coil leads to a misfire on that cylinder, and that throws off the natural balance of the cylinders firing in the proper order.

You can read some codes in the screen. You will need a chart to understand the code numbers. The Bentley manual has all the information in it that you need. The manual cost is about $100. You can find one at www.ecstuning.com

No special tools required to change plugs unless you drive a turbo.

[swilli89]

Thank you for your responses. I received an OBD code "P0306" - "Cylinder 6 Misfire Detected.

I will change the spark plug tomorrow, then move on to the coil itself.

Quick question, how do I tell which cylinder is cylinder #6?

I'll report back later!

Edit: Also I noticed a strong scent of gas when I fired it up to get the code.

[Pilgrim]

Thank you for your responses. I received an OBD code "P0306" - "Cylinder 6 Misfire Detected.

I will change the spark plug tomorrow, then move on to the coil itself.

Quick question, how do I tell which cylinder is cylinder #6?

I'll report back later!

Edit: Also I noticed a strong scent of gas when I fired it up to get the code.

Nope, that's doing it backwards. First swap the coil with the cylinder next to it (it's a 6-cylinder, where do you think #6 is? Hint - not the front).

Then run it, see if the miss moves to cylinder #5 or if it stays on #6.

If it moves to #5, it's the coil. If it stays on #6, it's the spark plug.

Chances are the gas smell is unburned gas from the miss.

[MIKYZZ4]

Yep, now that the scan revealed the misfire and cylinder#, you can swap coils to determine whether the misfire follows the coil,
or remains at cylinder #6 due to a possibly failed sparkplug. The fuel smell could be caused by a leaking injector, but let's not assume anything yet,
let's stick to confirmation, one step at a time. Perform the swap, clear the codes, start her up and go for a drive cycle, to see if any codes reappear.

[swilli89]

ok guys that definitely makes sense. I will pull the coil from cylinder #6, switch it the #5. Clear the code and start it up and see what happens. if Cylinder 6 is still misfiring i will change the plug and if cylinder #5 is now misfiring I will change that coil.

Makes sense that the gas smell may be due to the misfire.

Your advice means a lot, thank you very much.

[swilli89]

Well I switched coils between 6 and 5, then between 5 and 1. and... problem remained with cylinder 6. Lo and behold I am now getting P0306 AND P0305 AND P0301, in addition to P0300. Everyone cylinder I tried the presumably bad coil now has a permanent misfire even with diff coils and/or plugs.

SOLVED: So after I tried the same bad coil in 3 cylinders and all 3 started reporting misfires. Basically I bought one new coil from the local Dealership (parts counter guy gave it to me at invoice, $88), then replaced all three cylinders that the old coil touched with new spark plugs. Basically, the bad coil was fouling any spark plug it touched! I didn't know coils could do this and can be a lesson for others.

I can't seem to clear the Service Engine Soon light so I will drive it for a while and see if it will clear itself now that it shouldn't be throwing new codes.

Thanks to all that helped out!

[MIKYZZ4]

The multiple misfire codes have me suspecting leaks in possibly the intake, CVV, or fuel tank ventilation Systems.
Unless you are not clearing the codes and letting them accumulate in the error memory.
A smoke test with a pro smoke machine, combined with a replacement set of sparkplugs, will identify all leaks.

[brachelle]

Agree with the advice of reading codes. You can diagnose a bad coil pretty easily. The coil sits above each spark plug. A bad coil leads to a misfire on that cylinder, and that throws off the natural balance of the cylinders firing in the proper order.

You can read some codes in the screen. You will need a chart to understand the code numbers. The Bentley manual has all the information in it that you need. The manual cost is about $100. You can find one at www.ecstuning.com

No special tools required to change plugs unless you drive a turbo.

If service engine light is on would obd not tell you q code for cause or service engine light

[nuke21]

A smoke test with a pro smoke machine, combined with a replacement set of sparkplugs, will identify all leaks.

https://youtu.be/Np_duzsaZxI

You don't need a "professional" smoke machine. This smoke machine has been giving perfect results for years and I can do it in my garage by myself.

[MIKYZZ4]

https://youtu.be/Np_duzsaZxI

You don't need a "professional" smoke machine. This smoke machine has been giving perfect results for years and I can do it in my garage by myself.

Not necessarily, but if you haz the skilz, go for it.