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kino0924 kino0924 is offline
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Default Jerking off on very slow speed - 07-15-2018, 01:27 AM

Hi.

I am currently facing very rare situation and would like ask experienced members in forum.

It is 2009 335i automatic at 89km

Car does not throw any misfire code but I feel car is jerking off when I go real slow speed.
When I slightly release break pedal at D, I feel like car is like moving forward and backward.
Also when I throttle car little hard, I feel some unknown un-smooth that isn't like any other n54 car.

About 8k ago, I replaced all 6 plugs and coils to new NGK and Eldor
I checked smoothness value of engine and theres some abnormal reading at cylinder 6
cylinder 1 goes about -1.5~0 and other cylinders about -0.8~0
But cylinder 6 goes about 1.5~2.5 which is quite off.
I switched plugs and coils to different cylinder and see if the value moves but it was same.

So I suspected injector and decided to change it.
Im currently broke at this time so I only changed cyl6 to index 12 injector
Other cylinders have idx 6~7.

I coded new injector but the problem still exists and and smoothness value is still same.

Now, I am out of ideas and cant suspect anything else.
Next thing I might do is walnut blast but not sure this is because of carbon build up

I also checked some other readings from DME to see any abnormal values but I have no reference point to compare.


Cane someone please give me guide or hints of this unique problem?

Thanks alot in advance!
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Terry @ BMS's Avatar
Terry @ BMS Terry @ BMS is offline
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Default 07-15-2018, 10:10 AM

Sorry it's hard to take the post seriously with that title.


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kino0924 kino0924 is offline
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Default 07-15-2018, 10:45 AM

Hello Terry, Thanks for reply!

I couldn't find any better word to describe the situation lol
Car slowly moves forward while entire car body is shaking back and forth...
Is there any better word to describe this motion? hahahaha
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Mike_L Mike_L is offline
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Default 07-15-2018, 11:15 AM

Quote:
Originally Posted by Terry @ BMS
Sorry it's hard to take the post seriously with that title.
I was gonna say something similar, but figured it would show how immature I am.


Mike Levy
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LessIsMore's Avatar
LessIsMore LessIsMore is offline
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Default 07-15-2018, 11:40 AM

That title is too much OP, it's an American English euphemism for ... well, duckduckgo it.

Anyway ...

Do you have any mods?

I don't understand what you're talking about with cylinder 'smoothness' values and cyl 6 vs others. Since it's not throwing misfire codes or any others, it's probably not injectors/plugs/etc.

It could be carbon build up if a walnut blast has never been performed ...

Are you sure it's an issue with the engine? Is there any vibration/noise/etc. when it jerks ? What your describing could possibly be a driveline issue (bad axle, carrier bearing, etc.). Or even a sticking brake caliper?

I would stop throwing parts at it and instead try to eliminate non-spark/fuel possibilities.


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2009 535i - 548whp - sold
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thm8d thm8d is offline
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Default 07-15-2018, 12:47 PM

I literally laughed so loud my wife thought I was going crazy lol
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Rob@RBTurbo Rob@RBTurbo is offline
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Default 07-15-2018, 01:11 PM

ROFL!


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kino0924 kino0924 is offline
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Default 07-15-2018, 09:44 PM

Quote:
Originally Posted by LessIsMore
That title is too much OP, it's an American English euphemism for ... well, duckduckgo it.

Anyway ...

Do you have any mods?

I don't understand what you're talking about with cylinder 'smoothness' values and cyl 6 vs others. Since it's not throwing misfire codes or any others, it's probably not injectors/plugs/etc.

It could be carbon build up if a walnut blast has never been performed ...

Are you sure it's an issue with the engine? Is there any vibration/noise/etc. when it jerks ? What your describing could possibly be a driveline issue (bad axle, carrier bearing, etc.). Or even a sticking brake caliper?

I would stop throwing parts at it and instead try to eliminate non-spark/fuel possibilities.

Car used to run with MHD Stg1 but now its back to stock flash (not map 0)
Also, the car has DCI and chargepipe with tial bof
One last thing is Alpina B3 Transmission flash.

The smoothness value is something that you can monitor from INPA or ISTA-D
Also, some after market diagnostic tool provides this info as well.
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kino0924 kino0924 is offline
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Default 07-17-2018, 10:31 AM

Hmm its getting bad...
Today, I noticed that I have engine light so I checked with my generic scanner
(I didnt have my full scanner because I was on my way to work)
I noticed P0306 which is cyl 6 misfire
Also, I started to notice oil consumption started.
Not sure its burning or leaking but this isnt good sign i guess...

Anyone had damaged n54 without extensive mods?

Thanks,
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treehouse treehouse is offline
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Default 07-17-2018, 12:08 PM

All of this just sounds like misfires to me from the cylinder 6 injector. IIRC, you have to change an entire bank (1-3 or 4-6) at the same time. Did you re-code after changing the injector?
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LessIsMore LessIsMore is offline
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Default 07-17-2018, 12:19 PM

Quote:
Originally Posted by treehouse
All of this just sounds like misfires to me from the cylinder 6 injector. IIRC, you have to change an entire bank (1-3 or 4-6) at the same time. Did you re-code after changing the injector?
Agree, replace the other two injectors in the bank, and might as well do new plugs while you're there to eliminate that possiblity, since they're cheap.


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kino0924 kino0924 is offline
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Default 07-19-2018, 12:37 AM

Ok I have some bad news.
I went to indy shop to do compression/leak down test
Cylinder 6 has serious leak.
Other cylinder has about 210 psi compression but cyl 6 has 140 psi
The shop also said cyl 6 has about 30% leak.

So now, I have about 3 scenarios I guess...
1. ****ed cylinder wall and piston ring
2. Bent valve
3. Excessive Carbon buildup that blocks valve

Option 3 is one that Im dreaming but has anyone saw something like this case?
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LessIsMore LessIsMore is offline
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Default 07-19-2018, 07:33 AM

#3 seems pretty unlikely ...


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