Still can’t figure it out - stumble/irratic idle

[jaye944]

rather than doing multi-posts

1> mine are NGK (real OEM shows that)

2> OEM/OE what ever, apparently the dealer ones are preferred because they are properly gapped, I think that is the main issue in somne car problems

3> Mine does a hiccup exactly how you describe, I call it a heart attack moment, because my heart flips every-time I feel that. If I remember right, every time, my car has done that it's been just before a coil pack has gone.
no.2 and no.5 now. My plugs are worn, but I'm not having issues now/yet.
I'm wondering if the coils can "start" to go but not drop a code.

The coil packs are under w/tee for me so they only do them as when.

I guess if I was doing it my self, I'd change the whole set out, same thing as sparks, you'd do a whole set right ?

I know from the forums, that because of the construction the coils generally go without warning and not "always" recommended to change a whole set out.

"However" I am old school, if a car of mine was out of w'tee. In those symptoms, I would do full set, Plugs, Coils and air filter, and check for vacuum leaks.

IMHO based on experience and talking to techs, mechs and posters, filling up with different grades/tiers of gas and fuel additives, does nothing.

Using the wrong grade of gas/tier your ecu will manage that.though your throttle may feel flat. And most normal fuel has ALL the additives it needs, and it is just aplacebo effect or at the very least a prev.maintenance effect.
ONCE your car is doing this, there is a fault. which needs to be found and rectified.


Not meaning to put ANYONE's nose out of joint, just IMOHO

Originally Posted by kb2wji

My '11 128 is doing the same thing. It's very subtle (nobody notices but me) and it's only once in a while. If i'm at a stop light it might very subtly "hiccup" really quick. I did change my plugs with BMW OEM's about 6 months ago. I also changed the coil packs with the "high performance" red ones from BavAuto (apparently "high performance" is BavAuto speak for "chinese made crap"....I digress...) I'm going to try the fuel additive and see if that helps, but i'll be following this thread nontheless

[Tuxedo]

The reason I came to this forum in the first place was this issue. It's been the result of 1 stall and numerous near stalls. this was on a 2011 with N51 auto. It is a mostly known issue on the 135i DCT and requires DME update and it's been a few years since ive looked at this update-
SI B12 09 12 Engine Electrical Systems April 2013 Technical Service
NOTE: SUPERCEDED BY SIB 12 15 14
N55 WITH DOUBLE-CLUTCH TRANSMISSION: IDLE FLUCTUATES WHEN STOPPED

After update 12 15 14 it was still there but never close to stall and mild in irritation levels. Bad Coils will amplify this idle issue too so if the current Coils have 30k replace them and then hit up BMW for an update.

[MightyMouseTech]

Originally Posted by turbosl2

My car came with NGK plugs. The BMW plugs ARE exactly the same, same part number from NGK. The plugs being incorrect are not the problem. They were fine for many years. Maybe one is going bad or a coil is acting up but I won’t know until I swap everything to new the end of the week. I suspect there is something else going on and I can’t solve it because nothing in the computer shows an issue

One could have a cracked ceramic. That will cause random misfires.

[Mr Gasser]

NGKs have to be gapped, what gap are you using? Also check for any transmission cooler line leaks...

[Dackelone]

Originally Posted by kb2wji

My '11 128 is doing the same thing. It's very subtle (nobody notices but me) and it's only once in a while. If i'm at a stop light it might very subtly "hiccup" really quick. I did change my plugs with BMW OEM's about 6 months ago. I also changed the coil packs with the "high performance" red ones from BavAuto (apparently "high performance" is BavAuto speak for "chinese made crap"....I digress...) I'm going to try the fuel additive and see if that helps, but i'll be following this thread nontheless

I think your next step would be to clean your injectors with a professional cleaner - that bypasses the car's fuel system, for a more intense fuel injector cleaning. It could be that one of your injectors doesn't spray/atomize well at idle/low speeds.

Dack

[MightyMouseTech]

Originally Posted by Mr Gasser

NGKs have to be gapped, what gap are you using? Also check for any transmission cooler line leaks...

If an NGK plug has an "11" at the end of the part number, it is pre-gapped to 1.1 mm.

[Happy Jose]

Sounds like a failing fuel injector. I'd dump a can of cleaner in. That won't cure the problem, but it might last a bit longer.

With a failing injector, the miss will get worse until the engine won't run. You might smell gas and get back fires. A scanner will reveal a failing injector.