Rough idle on startup

[titium]

I get a rough idle occasionally on startup. The RPM seem stable but you can feel the car shaking. No codes thrown, and goes away once warmed up.

I am thinking leaking injectors? Is there a way to tell which injector(s) if no codes are thrown?

Has anyone had any luck with injector cleaner such as techron solving this issue?

N54 with new plugs, and just walnut blasted.

[VRG_135]

What did you find out? My N55 idles very roughly when A/C is on......and its gonna be on a lot here in Dallas.

[titium]

two tanks with techron cleaned it right up

was pretty good after the first tank but i was doing an oil change soon so for good measure I ran techron in the second tank.

injectors must have been pretty gummed up... by about 40km into the first tank the throttle response was noticeably better by half a tank night and day. took about a tank and 1/4 to get a rock solid idle.

[jaye944]

it's normal,

in fact some where in the manual it says that some roughness/shake will occur, I was worried and mine shook quite harshly but it goes off

only from super cold

its fine

no additives will fix it,
it's just how the engine is designed

Originally Posted by titium

I get a rough idle occasionally on startup. The RPM seem stable but you can feel the car shaking. No codes thrown, and goes away once warmed up.

I am thinking leaking injectors? Is there a way to tell which injector(s) if no codes are thrown?

Has anyone had any luck with injector cleaner such as techron solving this issue?

N54 with new plugs, and just walnut blasted.

[titium]

lol I can assure you it's not 'normal' unless you're talking about cold start at sub 0 ambient temps which we don't have in Australia so I wouldn't know.

mine also had some roughness when started after being turned off for a few minutes. after the techron it's all gone.

[jaye944]

according to the manual it is, I'll have a look for the proper wording

I've had it in summer temperatures as well as cold, usually on a cold start-up overnight. the roughness, can be bad but settles down after 30secs

Originally Posted by titium

lol I can assure you it's not 'normal' unless you're talking about cold start at sub 0 ambient temps which we don't have in Australia so I wouldn't know.

mine also had some roughness when started after being turned off for a few minutes. after the techron it's all gone.

[jaye944]

this is for the 1M manual, from talking to some people, this is common
so I believe this is the issue, had my car low millage for 7 months or so, summer and winter, after 30seconds its gone again only from cold start up

"Warming up the engine
During the warm-up phase, the high-performance V8 engine runs a little more roughly due to its emissions control system.
For technical reasons, the exhaust system sounds slightly metallic when the engine is
cold."

[titium]

What I was experiencing was definitely not normal. Also last time I checked the 1m didn't have a v8.

[jaye944]

interestingly after my £1 coil pack and spark plug was replaced, the shake has not been as bad, but still get about 30sec's of rough idle

[jaye944]

as second interestingly thing.

I started to monitor my starts, after this thread

I've found cold starts (early morning - digits) a very mild, tremor for about 30 sec's
then fine, same thing if left for say more than 8 hours (like going home from work)

B4 it was really lumpy, since the coil pack and plug was replaced I've had no probs.

So maybe depending on the SEVERITY of the shake...

I would say yes it is common but it should not be that bad

HTH

[qcodec]

My 135i shows sudden(almost half second?) stop of engine cycle and return normal condition.

It looked like the engine was having a heart attack.

[VRG_135]

My 2012 135 is a little rough upon start. But when I accelerate lightly from a stop (after the car has warmed up), the car shudders and acts like its going to die. It also does this when slowing to a stop. This activity is especially bad with the AC on. Will walnut shell blasting fix this?

[titium]

how much milage on the car? if it's below 80k km/ 50k mi then it's doubtful that carbon buildup in the intake is your issue.

could be anything from leaking injectors to a small boost leak.

[pepper135I]

Originally Posted by titium

I get a rough idle occasionally on startup. The RPM seem stable but you can feel the car shaking. No codes thrown, and goes away once warmed up.

I am thinking leaking injectors? Is there a way to tell which injector(s) if no codes are thrown?

Has anyone had any luck with injector cleaner such as techron solving this issue?

N54 with new plugs, and just walnut blasted.

when ever i have ANY amount of e85 in my tank my car does this (i know regular gas has roughly ~10%) but maybe you got a bad batch of gas? i really wouldnt worry too much. n54s r known to sound and feel rough on cold starts. after a few tanks of 91 and injector cleaner my idle is also alot more smooth but still a typical n54