Jump to content
Sign in to follow this  
Jacko

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

Recommended Posts

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

 

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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.

 

  • Like 1

Share this post


Link to post
Share on other sites

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. 

35439502_10155244022492693_7608323677674799104_o.jpg

35381737_10155244021842693_904538898724552704_o.jpg

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

Replaced Vanos solenoids.

No change. #fingthing :D

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

Eccentric shaft wear is common so could be that?

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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.

 

 

  • Like 1

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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? 

Share this post


Link to post
Share on other sites

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... 

95ce6c38f6cad66f4f5edaa6f0cb8071.jpg

Edited by Jacko
  • Like 1
  • Haha 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×