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Jacko

N52B30 E91 330 - Coughing on WOT from idle (video) - *SOLVED*

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Car has done this for awhile, mechanics couldnt find fault, its a little disconcerting sometimes as it can do it when acclerating from lights/crossing a road/going around a round about.

Under no/low load, WOT only, from idle only, the engine hesitates and splutters around before accelerating. Sometimes it lasts seconds, sometimes its just a cough. Only does it from idle, and otherwise works perfectly. 

  • No fault codes. Nadda.
  • Ive reset the DME by pulling the battery. No change, No change in fault code logging.
  • Ive pulled the vanos solenoids and cleaned them. No change, didnt look dirty either. 
  • Done the throttle calibration thing. No change.
  • According to service history plugs are less than 20k old, everything else has many thousand k left on it. Doesnt feel likes it misfiring anyway (and surely the DME would pick a misfire up)

Any ideas? My next step was to just change the vanos solenoids and cross fingers. Anyone come across this before? Im trying to avoid unleashing the parts cannon at it to solve! :D

 

Edited by Jacko

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Eccentric cam sensor seal leaking and filling the plug with oil ? Seems plausible. 

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Try reset all "DME adaptations". I have seen a reset fix this issue you have described before. You will need a good quality scanner to carry out this service function. Disconnecting the battery does not reset the DME unfortunately.

 

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Eccentric sensor plug is dry, was a nice pool of oil beneath the valvetronic motor and down the sparkplug tube for #4, doesnt look like the valvetronic seal is leaking, just that someone decided that oil belonged on the outside of the engine and not in the sump.

Will clean it all up and see what happens. 

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No change. 

 

Anyone handy have the right box of tricks to reset the adaptation on DME?

 

Edit - Anyone know if Carly can do this? Been playing with the idea of buying one.

Edited by Jacko

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Replaced Vanos solenoids.

No change. #fingthing :D

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I am quite new to BMWs, but I have seen m52tu in z3 that is clearly misfiring does not throw any code. And I have had a Suzuki Swift Sport back in China with highish kms that hesitates and splutters only in 2nd and 3nd WOT at low rpm. it didn't throw any code but turned out the coil pack rubber is old, and for some reason, it is sparking between the spark plug tube and the cylinder head, not on the spark plug causing misfires. 

Since both your bimmer have n52, maybe swap the plugs and coil pack just to be sure?

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Eccentric shaft wear is common so could be that?

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Decided to try science the sh*t out of it... Compare the happy N52 with the sad one. Hopefully something obvious pops up, for some reason I cant graph the accelerator pots output, but will compare the two. 

 

Sad one tomorrow...

130 smash go pedal.png

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Edit - Try that again with the right data....

 

  • Throttle (Manifold) is open for way longer on the bad one before RPM increase.. which makes sense.
  • Fuel trim 2 cranks up on the bad one, good one it leans out.
  • AFRs look similar.
  • Timing looks Similar. 
  • Vacuum looks similar. 

Anyone spot anything else? I wonder if its fuel now :/ The fact that vacuum is inline with the throttle (valvetronic) makes me think the valvetronic motor is fine

N52 Good Vs Naughty.xlsx

N52 Good.png

N52 Bad.png

Edited by Jacko

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Mine was missing under load at low rpm (under 2000), No CEL for misfiring until it got really really bad one day.  Replaced the plugs and it's 95% gone, now there's just an occasional stumble when idling in drive.

If keeps doing it I'm going to buy a new set of coils.

 

 

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Parts cannon unleashed... Coils and plugs ordered.... 

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Thinking about this a bit more... Car uses roughly twice the oil of the other one, and drinks gas more than I would have expected (more than the extra weight and auto should really).

 

I wonder if theres is something goofy happening with the CCV system? 

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New plugs and coils - No change. Reset adaptations - No change.

Have been watching the oil level, im conviced something odd is happening as it fluctuates by 700ish ml. Wondering if there is a block in the oil seperator and its filling and dumping (into the sump and or intake). The 130s oil level is solid as a rock in comparison. 

Ordered new CCV system kit... 

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Edited by Jacko
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  • Haha 2

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bugger!

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SOLVED!! *dancing*

 

Installed ISTA+ and got a K+DCAN cable. A few hours of naffing around to get it installed and talking and BOOM! 

Reset the engine DME learning and adaptations and its solved. Also using less gas and pulling harder, it doesnt feel way slower than the 130 anymore...

 

It was like flicking a switch between runs like a dog and runs like new...

Yay for piracy :D

yay.jpg

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At least the parts cannon didn't punish you to much and you have given your engine some love in the process.  I'm picking the software used the first time around was not up to the task of correctly deleting DME adaptations?

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Yeah the only thing that actually worked was ISTA+

CCV kit is stuck in customs, but whenever it turns up Ill pull the intake manifold and replace it to, as  the oil level fluctuating is still weird. Car drives mint though.

 

Any theories on how the DME learns to behave so poorly? Im assuming it was just cranking the fuel trims looking at the graphs. 

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Have never given any serious thought as to why the DME takes on such adaptations but at a guess I would say the valvetronic is not opening the valves correctly for that particular load/rpm range. You may find the fault return after a while and require a adaptation reset once again. 

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Replaced the CCV system today, pig of a job, but intake was full of oil. I suspect the fuel trims were getting butchered by sensors covered in oil from the separator not draining correctly. At least both DISA valves look sweet as (and all you N54/55 guys can be jealous as of those intake valves.. ;)

All appears good, will keep an eye on the oil consumption now and see if have solved it. 

 

 

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Edited by Jacko

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