Rough Idle on Cold Start

skaper · 06-06-2020, 02:34 PM

It looks like there are a number of these threads already. I guess in order to help the next person out and seek advice, I am going to log this here.

Quick timeline:

*edit -79K coils & plugs (OEM BMW)
-80K on well-kept N55 335
-Oil filter housing gasket kit (OEM BMW)
-Car runs great for the next few hundred miles

No codes, rough idle appears on cold start, engine stutters. Car as even died on one cold start when putting in reverse. Zero issues after a minute of warmup time.

-Fully charged battery
-Vanos Solenoids replaced (OEM BMW)
-Tensioner / pulley / belt kit (OEM BMW)
-1/7 JB4 reset

Still got a rough idle this morning, no codes. My next step is to clean the MAP and MAF sensors. Any other suggestions?

cheers

Here is a bad phone shot, pulled from FB

Phil325i · 06-06-2020, 03:46 PM

Classic symptom of failed injector(s). They leak overnight and the engine is rough on cold start-up until the excess fuel has burned off. Pull your spark plugs after sitting overnight. One or more will be black, wet and smell of fuel.

P.S. BMW recommend not just replacing one injector. You need to replace all in the same bank (cyl 1-3 or 4-6) or preferably all six. And get the most up to date version. I think the injectors for your car are now at version 12.

skaper · 06-06-2020, 04:02 PM

Quote:

Originally Posted by Phil325i

Classic symptom of failed injector

Thanks for the insight. I was hoping that wouldn’t be the case but sounds like it will be. I did just do coils and plugs about a thousand miles ago. Typical to replace the spark plugs along with the injectors?

I was trying to get all the big items out of the way before more fun parts... but here we are!

MightyMouseTech · 06-06-2020, 04:09 PM

Quote:

Originally Posted by Phil325i

Classic symptom of failed injector(s). They leak overnight and the engine is rough on cold start-up until the excess fuel has burned off. Pull your spark plugs after sitting overnight. One or more will be black, wet and smell of fuel.

P.S. BMW recommend not just replacing one injector. You need to replace all in the same bank (cyl 1-3 or 4-6) or preferably all six. And get the most up to date version. I think the injectors for your car are now at version 12.

N55, you can do them individually.

skaper · 06-12-2020, 09:30 AM

Just closing this one out. After this last week I haven’t had any issues. I the car even sat for 24 and 48 hours a few times before cold starts. Not sure why this problem went away or worked itself out. I’ll start planning for the injectors to go but for now, I hope the issue is gone and I can install my DP this week!

06-06-2020, 02:34 PM	#1
skaper Private First Class 45 Rep 106 Posts Drives: E90 N55 M-Sport Join Date: Oct 2012 Location: Portland iTrader: (1)	Rough Idle on Cold Start It looks like there are a number of these threads already. I guess in order to help the next person out and seek advice, I am going to log this here. Quick timeline: edit -79K coils & plugs (OEM BMW) -80K on well-kept N55 335 -Oil filter housing gasket kit (OEM BMW) -Car runs great for the next few hundred miles No codes, rough idle appears on cold start, engine stutters. Car as even died on one cold start when putting in reverse. Zero issues after a minute of warmup time. -Fully charged battery -Vanos Solenoids replaced (OEM BMW) -Tensioner / pulley / belt kit (OEM BMW) -1/7 JB4 reset Still got a rough idle this morning, no codes. My next step is to clean the MAP and MAF sensors. Any other suggestions? cheers Here is a bad phone shot, pulled from FB __________________ Kennethavery.com // Portland Real Estate Wagner Evo 1 IC // Active Autowerke CP // JB4 + BEF // CAtuned Coilovers // AR Design D/P // Future Classic Spacers // E46 OE CSL Wheels // (PURE Stage 2 w/ wedge next!) Last edited by skaper; 06-06-2020 at 05:54 PM..*
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06-06-2020, 03:46 PM	#2
Phil325i Brigadier General 616 Rep 3,194 Posts Drives: E92 325i MSport Coupe Join Date: Apr 2012 Location: UK South East iTrader: (1) Garage List 2009 BMW 325i Coupe [6.00]	Classic symptom of failed injector(s). They leak overnight and the engine is rough on cold start-up until the excess fuel has burned off. Pull your spark plugs after sitting overnight. One or more will be black, wet and smell of fuel. P.S. BMW recommend not just replacing one injector. You need to replace all in the same bank (cyl 1-3 or 4-6) or preferably all six. And get the most up to date version. I think the injectors for your car are now at version 12. __________________ E92 pre-LCI 325i - Ohlins R&T; H&R spacers; M3 strut brace; Swift thrust sheets; 3 x chassis braces; diff brace; N53 V-brace; 034 subframe inserts; BMS clutch stop; BMS CDV; RE g/box mounts; Delrin shift bushes; Saikoumichi OCC; Cyba scoops; BMW Perf Exhaust; HEL s/steel brake hoses; M3 rear spoiler; Recaro Sportster CSs; M3 white dash LEDs; LED Angels; LED side repeaters; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof/clear front
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06-12-2020, 09:30 AM	#5
skaper Private First Class 45 Rep 106 Posts Drives: E90 N55 M-Sport Join Date: Oct 2012 Location: Portland iTrader: (1)	Just closing this one out. After this last week I haven’t had any issues. I the car even sat for 24 and 48 hours a few times before cold starts. Not sure why this problem went away or worked itself out. I’ll start planning for the injectors to go but for now, I hope the issue is gone and I can install my DP this week!
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