Rough Idle in cold start, misfire

kcome · 08-25-2019, 05:54 PM

Hi all

I had a 135i running well for the past years.

From July to Aug, in Australia late winter, I found the engine has a couple of intermittent power drop for 1-2 secs in first 2-3 minutes in acceleration from cold start, it only happen in cold start. After two weeks like this, car showed a cylinder 2 misfire code and I got a mechanic had a look. He changed the cracked valve cover (costs a lot) and said fuel injectors need to be replaced/repaired. I haven't done the fuel injector fixing yet. This car has less than 44K US miles.

Before the fixing, I always drive away immediately after start. Now I will wait for the rpm to drop from 1200 to about 1000-900, about less than 1min, in cold start before driving away. During idle warm up the engine shakes a bit, more than warm engine idling in red-light, but it's gone afterwards. Now there seems no issue at all. The torque app shows cylinder 2 has about 50+ misfire avg in last 10 trips before fixing. After fix I had one read, it shows about 20+ misfires. The car was kept in underground carpark overnight, when it's start the temp reading was 19C, but when driving on the road it could go between 6-10C in early morning. Last winter it was no issue and the car was kept in open air parking.

Could u guys give some suggestion what the cause might be? I'm going to try some fuel injector cleaner first. Also the engine oil was changed this Jan. I'm considering servicing it before any repairs.

Thanks a lot

elitesales305 · 08-25-2019, 07:53 PM

My chiks car started shaking at red lights..its a beater keep in mind..
Changed a spark plug.. shaking went away
Given that u have the injector issues might wanna start with plugs and injectors usaually if u change one the rest are about to go.. sad that u only have 44k on the car and having these issues so early.. sometimes shit sitting is just as bad as u ragging on it im not mech tho but maybe check the plugs cheap and u can do it urself..

blue135 · 08-25-2019, 09:35 PM

May not apply, but shortly before I bought my 2008 135i about four years ago, the prev owner was having all kinds of drivability problems. Shop changed plugs & Coils, no change. Changed injectors, no change. Next on list was walnut blast. Now I have a great driving car.

Thunderguts · 08-26-2019, 09:00 AM

You shouldn't need a walnut blast with so few miles. I would guess coils first. I would think a bad eccentric sensor might also cause your issues. Unfortunately you already paid to pull the valve cover, which would need to be done again to replace the sensor.

blue135 · 08-26-2019, 02:35 PM

Thunderguts - perhaps you are right about the mileage, I can only say that the incident I described occurred between 46k and 47k miles. My bad for omitting that small detail

kcome · 08-26-2019, 04:44 PM

Thanks guys for giving thoughts.

Mine is a MT one and I had no good habit of pressing clutch to full early before a stop so that means idling a lot of times. Maybe that is could cause carbon? (oh, one more bad habit: i used to "spot accelerate", press gas 0.5 second and release completely(or 98%) for 1.5 seconds, and gas again. I always get just enough not so hard acceleration and then release gas for about 80% of my daily driving)

Also the battery seems to be the original AGM VARTA one never replaced. It shows yellow battery light on bigger screen sometimes: a) i stop engine in a long red light with radio on. b) stop driving/engine and not pull out the key for 2 minutes or longer. a friend remind me that over night in garage could also cause engine to charge battery hard once it starts. Considering to get battery checked/replaced.

The car drives about 7-8km one way in morning and return trip in afternoon. It's always better in the afternoon than early morning.

dtla1 · 08-27-2019, 12:06 PM

Quote:

Originally Posted by kcome

Thanks guys for giving thoughts.

Mine is a MT one and I had no good habit of pressing clutch to full early before a stop so that means idling a lot of times. Maybe that is could cause carbon? (oh, one more bad habit: i used to "spot accelerate", press gas 0.5 second and release completely(or 98%) for 1.5 seconds, and gas again. I always get just enough not so hard acceleration and then release gas for about 80% of my daily driving)

Also the battery seems to be the original AGM VARTA one never replaced. It shows yellow battery light on bigger screen sometimes: a) i stop engine in a long red light with radio on. b) stop driving/engine and not pull out the key for 2 minutes or longer. a friend remind me that over night in garage could also cause engine to charge battery hard once it starts. Considering to get battery checked/replaced.

The car drives about 7-8km one way in morning and return trip in afternoon. It's always better in the afternoon than early morning.

Replace the battery first. I know it sounds weird, but random issues have sometimes come up with dying/dead batteries.

kcome · 08-28-2019, 03:10 AM

Thanks dtla1.

The battery was replaced yesterday, no cure for startup misfire.

Today goes to a mechanic to change Spark plugs, was told it doesn't solve the problem. Considering use an aftermarket one for short period of time. Not sure whats the downside on this. Thanks for posting your feedback.

MightyMouseTech · 08-28-2019, 05:22 AM

Misfire on cold start like that is almost always injectors.

08-25-2019, 05:54 PM	#1
kcome Registered 0 Rep 3 Posts Drives: BMW 135i Join Date: Aug 2019 Location: Sydney, Australia iTrader: (0)	Rough Idle in cold start, misfire Hi all I had a 135i running well for the past years. From July to Aug, in Australia late winter, I found the engine has a couple of intermittent power drop for 1-2 secs in first 2-3 minutes in acceleration from cold start, it only happen in cold start. After two weeks like this, car showed a cylinder 2 misfire code and I got a mechanic had a look. He changed the cracked valve cover (costs a lot) and said fuel injectors need to be replaced/repaired. I haven't done the fuel injector fixing yet. This car has less than 44K US miles. Before the fixing, I always drive away immediately after start. Now I will wait for the rpm to drop from 1200 to about 1000-900, about less than 1min, in cold start before driving away. During idle warm up the engine shakes a bit, more than warm engine idling in red-light, but it's gone afterwards. Now there seems no issue at all. The torque app shows cylinder 2 has about 50+ misfire avg in last 10 trips before fixing. After fix I had one read, it shows about 20+ misfires. The car was kept in underground carpark overnight, when it's start the temp reading was 19C, but when driving on the road it could go between 6-10C in early morning. Last winter it was no issue and the car was kept in open air parking. Could u guys give some suggestion what the cause might be? I'm going to try some fuel injector cleaner first. Also the engine oil was changed this Jan. I'm considering servicing it before any repairs. Thanks a lot Last edited by kcome; 09-16-2019 at 09:46 PM..
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08-25-2019, 07:53 PM	#2
elitesales305 shmo 383 Rep 1,026 Posts Drives: honda Join Date: May 2017 Location: no where iTrader: (0)	My chiks car started shaking at red lights..its a beater keep in mind.. Changed a spark plug.. shaking went away Given that u have the injector issues might wanna start with plugs and injectors usaually if u change one the rest are about to go.. sad that u only have 44k on the car and having these issues so early.. sometimes shit sitting is just as bad as u ragging on it im not mech tho but maybe check the plugs cheap and u can do it urself.. __________________ No sig
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08-25-2019, 09:35 PM	#3
blue135 Captain 378 Rep 654 Posts Drives: 2008 135i Convertible Join Date: Aug 2015 Location: Sarasota, FL iTrader: (1)	May not apply, but shortly before I bought my 2008 135i about four years ago, the prev owner was having all kinds of drivability problems. Shop changed plugs & Coils, no change. Changed injectors, no change. Next on list was walnut blast. Now I have a great driving car.
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08-26-2019, 09:00 AM	#4
Thunderguts Major 789 Rep 1,005 Posts Drives: 2009 128i Sport MT Join Date: Jul 2018 Location: DFW iTrader: (0)	You shouldn't need a walnut blast with so few miles. I would guess coils first. I would think a bad eccentric sensor might also cause your issues. Unfortunately you already paid to pull the valve cover, which would need to be done again to replace the sensor.
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08-26-2019, 02:35 PM	#5
blue135 Captain 378 Rep 654 Posts Drives: 2008 135i Convertible Join Date: Aug 2015 Location: Sarasota, FL iTrader: (1)	Thunderguts - perhaps you are right about the mileage, I can only say that the incident I described occurred between 46k and 47k miles. My bad for omitting that small detail Last edited by blue135; 08-26-2019 at 02:37 PM.. Reason: add words
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08-26-2019, 04:44 PM	#6
kcome Registered 0 Rep 3 Posts Drives: BMW 135i Join Date: Aug 2019 Location: Sydney, Australia iTrader: (0)	Thanks guys for giving thoughts. Mine is a MT one and I had no good habit of pressing clutch to full early before a stop so that means idling a lot of times. Maybe that is could cause carbon? (oh, one more bad habit: i used to "spot accelerate", press gas 0.5 second and release completely(or 98%) for 1.5 seconds, and gas again. I always get just enough not so hard acceleration and then release gas for about 80% of my daily driving) Also the battery seems to be the original AGM VARTA one never replaced. It shows yellow battery light on bigger screen sometimes: a) i stop engine in a long red light with radio on. b) stop driving/engine and not pull out the key for 2 minutes or longer. a friend remind me that over night in garage could also cause engine to charge battery hard once it starts. Considering to get battery checked/replaced. The car drives about 7-8km one way in morning and return trip in afternoon. It's always better in the afternoon than early morning. Last edited by kcome; 08-26-2019 at 06:59 PM..
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08-28-2019, 03:10 AM	#8
kcome Registered 0 Rep 3 Posts Drives: BMW 135i Join Date: Aug 2019 Location: Sydney, Australia iTrader: (0)	Thanks dtla1. The battery was replaced yesterday, no cure for startup misfire. Today goes to a mechanic to change Spark plugs, was told it doesn't solve the problem. Considering use an aftermarket one for short period of time. Not sure whats the downside on this. Thanks for posting your feedback.
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08-28-2019, 05:22 AM	#9
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	Misfire on cold start like that is almost always injectors.
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