Car does what appears as misfire

[MZWIE]

After much Time and replacement of plugs, coils, vanos solenoids misfire Issue still exists.

Research reveals that a true misfire would Register a fault Code. No fault Codes presents.

I Contacted a bmw expert and he believes it could be the battery. What i cannot Understand is how an Issue with the battery would Manifest itself as what Feels like a misfire.

He mentioned State of Charge. I would think that if the battery is not charging then other electrical components would also have Problems.

Being an electrical Engineer this simply does not add up. Even my collegues also do not get it..

So could some one please enlighten me on this.

[ShocknAwe]

Do you still have the "misfire" if you turn off the A/C?

[MZWIE]

Yes. Have not Used ac in a while.

[Dackelone]

Are you sure you have the "correct" spark plugs? I would try a new set bought from a BMW dealer. Aftermarket ones can cause issues. Also make sure you have the right plugs for a N54, bc the N55 plugs ARE different.


Under WHAT conditions does your engine misfire? We could use more info. Might even be carbon build up issue.

[MZWIE]

Guys. Trust me when I say I tried everything. All parts came from dealer. Clenaed the intake valves as well.

According to a respected BMW person if this was a real misfire the ECU would have logged it. That is why he suggests the battery.

[MightyMouseTech]

It takes a LOT of misfires before you get a code.

Were the plugs torqued to spec? They take a surprisingly small amount of torque (22 Nm) Over-torquing can crack the porcelain and cause a misfire.

My car was running like absolute crap after I installed the plugs that came with my PPK kit, and turned out to be the wrong plugs for the car. Misfire like crazy. Did not register a code though.

[n2djazz]

Originally Posted by e34m5

After much Time and replacement of plugs, coils, vanos solenoids misfire Issue still exists.

Research reveals that a true misfire would Register a fault Code. No fault Codes presents.

I Contacted a bmw expert and he believes it could be the battery. What i cannot Understand is how an Issue with the battery would Manifest itself as what Feels like a misfire.

He mentioned State of Charge. I would think that if the battery is not charging then other electrical components would also have Problems.

Being an electrical Engineer this simply does not add up. Even my collegues also do not get it..

So could some one please enlighten me on this.

I had misfires at wide-open-throttle that started out-of-the-blue back in Jan 2013. It happened right as I turned 40,000 miles. I replaced the plugs to no avail. I put up with the w-o-t misfires until I got a misfire code in Oct 2013. That's ten months of driving before I got my first misfire code. And when it announced, the engine started running rough like a fricking lawnmower. I replaced my coils and it's been like-new ever since.

So what's my point? My experience is things have to get pretty severe before sw throws a code. Looking back, my SA advised to replace the coils in Jan 2013 when I brought it in…(I had already replaced the plugs myself.) But his advice didn't make sense. The car was fine until I went w-o-t. I went back to him in Oct 2014 (a yr after coil replacement) for brake work and told him I replaced the coils LIKE HE SUGGESTED. We had a good laugh.

Seeing how you have replaced everything else, try the battery. I believe BMW NA has a $50 rebate on battery replacements. It ends 31 Mar 2015 though. My battery is circa 6yrs old so I'm going to get that done before the offer ends. If it is the battery, maybe you can ebay your old coils for $100 bucks and recoup some monies.

[feeshta]

I can't offer any insight into this particular problem, but my old 08 135i would backfire as I coasted up to the stop sign down at the end of our road almost every time I drove it. Always wondered what caused that. It only did it after a cold start, and the stop sign was at the bottom of a hill. Had the dealer look at it twice and got the famous "unable to replicate the problem".

Hope you find the cause of your issues.

[GuamX1]

This has been happening to my car and the battery caused the problem. I had a weak 7 year old battery. I have not replaced it since it is on a tender, the previous tender probably was bad so that caused the weak battery. This cars are not good at charging a weak battery themselves at idle I dont think they even charge. Unlike old cars like my classic mini once your get it started and keep the revs up the battery charges it does not have a lot of electronics sucking up the juice.