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Discussion Starter · #1 ·
So as I have posted before I have an extremely rough idle at cold start and it makes me cringe every time I start it. I have been looking at a few different methods of removing the buildup and the best is obviously walnut blasting. As this can get very expensive and inconvenient at the stealer I looked up other options. The soak and scrub! What have people tried themselves? Has it worked? If you could start from day 1, would you buy the same equipment? Depending on the price gap I would like to get a blaster, but i don’t want to spend a fortune on the worlds best one either. I have no issues resorting to the spam and scrub but I do not want to put anything that isn’t supposed to be in my engine, well, into my engine. The soak and scrub I saw was brakleen and a brass brush. What if the brush sheds and gets some bristles into the engine? Just want to make sure I will not harm my beauty. Also are there any special tools involved?
 

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Discussion Starter · #3 ·
Sounds more like an injector/HPFP problem than carbon buildup. What is the index no. of your injectors?
Well my car is at 93,000m and has never been walnut blasted. It runs very rough cold, and can definitely still tell something is going on after it is to operating temp. But I hate!!!! Absolutely hate to drive it before it's warmed up because the car acts terrible. Once operating temperature is achieved power is on point and really goes like it's supposed to. I have been told it needs a good walnut blast. Maybe not? I'm not throwing any bad codes
 

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Mine is at 72k and never been blasted. There in no believable technical explanation for why carbon buildup will be an issue on a cold engine but not on a hot engine. Carbon buildup reduces airflow into the engine, hence it first becomes a issue when demand for intake air is high...........WOT and high rpm.....not at idle. If carbon buildup was so extensive that it interfered with idle, the engine probably wouldn't run above 2000 rpm.
 

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Discussion Starter · #5 ·
Mine is at 72k and never been blasted. There in no believable technical explanation for why carbon buildup will be an issue on a cold engine but not on a hot engine. Carbon buildup reduces airflow into the engine, hence it first becomes a issue when demand for intake air is high...........WOT and high rpm.....not at idle. If carbon buildup was so extensive that it interfered with idle, the engine probably wouldn't run above 2000 rpm.
So what do you suggest I do? How do I troubleshoot
 

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Discussion Starter · #6 ·
The car runs rough when warm, but only at a standstill. It is 90% better than cold start up but it is still a little tougher than it should be. I at the moment am running MHD and the power is all there. So I don’t know what else it could be
 

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Sounds more like an injector/HPFP problem than carbon buildup. What is the index no. of your injectors?
This is definitely worth considering. I had a similar rough running issue last fall so I started with plugs and walnut blast. When I did the walnut blast I noticed the valves in cylinder six were noticeably damp which I assumed was due to a bad injector. After this the car still ran rough so I took it in and ended up having all six injectors replaced. My car is a 2010 and had about 100k miles on it at the time I was figuring this stuff out.
 

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Discussion Starter · #8 ·
Sounds more like an injector/HPFP problem than carbon buildup. What is the index no. of your injectors?
This is definitely worth considering. I had a similar rough running issue last fall so I started with plugs and walnut blast. When I did the walnut blast I noticed the valves in cylinder six were noticeably damp which I assumed was due to a bad injector. After this the car still ran rough so I took it in and ended up having all six injectors replaced. My car is a 2010 and had about 100k miles on it at the time I was figuring this stuff out.
Well my spark plugs are decently new. How do I troubleshoot bad injectors? Wouldn't that throw codes?
 

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I had rough idle and misfiring that shook the car. I had a walnut nut blast and replaced 2 fuel injectors and now the car runs like the ultimate driving machine it is. :) Oh I only have 66,000 miles on her. 2009 535i xdrive,

see attached
Before
imagejpeg_01[1].jpg

After

imagejpeg_2[1].jpg
 

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Tried the soak and scrub. It sucked compared to blasting. If you are near Akron pick up 50lbs of shells from harbor freight and bring them over.


Sent from my iPhone using Bimmerfest
 

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Well my spark plugs are decently new. How do I troubleshoot bad injectors? Wouldn't that throw codes?
Does your check engine light work? Does it light when running poorly? Severe misfires will cause DME to disable the misfiring cylinder and this will set a code. However, misfire code will automatically clear on the next restart so you need to check for codes while light is on or while engine is running poorly. You can use a generic OBD reader if you're looking for misfires. The next time it's running poorly, shut off after 30 seconds or so and restart. This will give the misfiring cylinder(s) another chance to play nicely.
 

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Discussion Starter · #12 ·
I had rough idle and misfiring that shook the car. I had a walnut nut blast and replaced 2 fuel injectors and now the car runs like the ultimate driving machine it is.
Oh I only have 66,000 miles on her. 2009 535i xdrive,

see attached
Before
[iurl="http://www.bimmerfest.com/forums/attachment.php?attachmentid=727697&stc=1&d=1512690412"]
[/iurl]

After

[iurl="http://www.bimmerfest.com/forums/attachment.php?attachmentid=727705&stc=1&d=1512690412"]
[/iurl]
Tried the soak and scrub. It sucked compared to blasting. If you are near Akron pick up 50lbs of shells from harbor freight and bring them over.

Sent from my iPhone using Bimmerfest
So my question to both of you is what were the symptoms as to why you did the blast or scrub? As in did it run poorly all together or was it fine after the car warmed up. Was the car fighting itself to push power or was it fine.
 

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Discussion Starter · #13 ·
Well my spark plugs are decently new. How do I troubleshoot bad injectors? Wouldn't that throw codes?
Does your check engine light work? Does it light when running poorly? Severe misfires will cause DME to disable the misfiring cylinder and this will set a code. However, misfire code will automatically clear on the next restart so you need to check for codes while light is on or while engine is running poorly. You can use a generic OBD reader if you're looking for misfires. The next time it's running poorly, shut off after 30 seconds or so and restart. This will give the misfiring cylinder(s) another chance to play nicely.
Check engine light works. I have only ever thrown it off once and that was back when it was really bad! There was something in the tune that really screwed with it. I went back into the tuning setting and turned off a few things that I thought it may be. I'm pretty sure it was the "quiet cold start option"
 

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My car was throwing misfire codes. And would run rough. Walnut blasting eliminated it.


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Discussion Starter · #15 ·
My car was throwing misfire codes. And would run rough. Walnut blasting eliminated it.

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Did it always run rough? Did it get better as engine warmed up? Mine is terrible on cold start and slowly gets better but not 100% better just driveable better
 

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Mine was very inconsistent with throwing codes, I did get a few misfire codes which I would clear each time I did something like plugs or the walnut blast. I was getting a rough idle when cold and warm, it didn't really matter. I also got a couple really bad misfires where the car would jerk very hard during gear changes. I waited for it to throw a misfire code and then brought it in to the dealer.

The dealer took into account that I had replaced the plugs and done the intake cleaning, they were able to pull codes which led them to inspect the injectors which they found were leaking so all were replaced.
 

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Discussion Starter · #18 ·
Mine was very inconsistent with throwing codes, I did get a few misfire codes which I would clear each time I did something like plugs or the walnut blast. I was getting a rough idle when cold and warm, it didn't really matter. I also got a couple really bad misfires where the car would jerk very hard during gear changes. I waited for it to throw a misfire code and then brought it in to the dealer.

The dealer took into account that I had replaced the plugs and done the intake cleaning, they were able to pull codes which led them to inspect the injectors which they found were leaking so all were replaced.
Judging from this that means something else is wrong because mine is only bad at cold. So now what?
 

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When did the misfires start?

At 93k you're due for a walnut blast regardless if causes the misfire.

If you're on the west side of Wisconsin I'll rent you my walnut blaster and shop vac and attachments (I'll need a refundable deposit).
 

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Discussion Starter · #20 ·
When did the misfires start?

At 93k you're due for a walnut blast regardless if causes the misfire.

If you're on the west side of Wisconsin I'll rent you my walnut blaster and shop vac and attachments (I'll need a refundable deposit).
Where are you located
 
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