MINI N16 engine Rough idle.

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waterfox11
Newbie
Posts: 3
Joined: Thu Aug 09, 2018 4:46 am

MINI N16 engine Rough idle.

Post by waterfox11 »

Hi, First sorry for my english.

I have a mini that causes static engine misfire cylinder 4 when idling.
No significant problems were identified during vehicle acceleration.
but, After about 10 minutes in the idling state, a relief occurs in the cylinder No. 4.
At this time, the MIL lamp flashes and the P0304 Cylinder 4 Misfire Detected DTC code is recorded in the DME.
I found an interesting point in the compression pressure test with the wp500x sensor.
I could see a clear slope change in the induction stroke.

1. What does this mean?
Does the negative pressure that is not sufficiently formed during the suction stroke mean valve leakage or
timing control failure?


2. And how can the uneven bend of the end of the exhaust stroke be explained?

I am curious about your opinion of this waveform.
Thanks for your help.
Attachments
2018-08-11_16-54-39.jpg
2018-08-11_16-11-11.jpg

liviu2004
TwoWaves
TwoWaves
Posts: 472
Joined: Sat Mar 19, 2016 8:23 am
Location: Netherlands

Re: MINI N16 engine Rough idle.

Post by liviu2004 »

Can you put some bar in the waveform? V doesn’t make any sense to me.

speck
TwoWaves
TwoWaves
Posts: 63
Joined: Sun Mar 25, 2012 5:20 am

Re: MINI N16 engine Rough idle.

Post by speck »

Hi, how about psdata.

waterfox11
Newbie
Posts: 3
Joined: Thu Aug 09, 2018 4:46 am

Re: MINI N16 engine Rough idle.

Post by waterfox11 »

OK, I will measure again on Monday.
And I will attach the file.
Thank you.

kona
TwoWaves
TwoWaves
Posts: 66
Joined: Thu Feb 22, 2018 8:14 pm

Re: MINI N16 engine Rough idle.

Post by kona »

It looks like a problem with the exhaust valve (sometimes closed, and sometimes not) - the spring is broken, the valve is bent, ... ). :idea:

  It would be useful to make measurementswith with the wp500x :
- pressure in another cylinder;
- intake manifold vacuum;
- pulses from the exhaust.

In the picture, the timing does not look right, but it must be checked on another cylinder.

Technician
TwoWaves
TwoWaves
Posts: 705
Joined: Thu Apr 24, 2014 8:32 pm

Re: MINI N16 engine Rough idle.

Post by Technician »

The injection event looks too early, I could be seeing it wrong but it looks like the injection has taken place just as the inlet valve is about to open. The inlet valve looks as though it is starting to open but then sees some type of pressure ramp where the pressure sort of levels out, and then again starts to induce on the induction stroke. In the remaining induction compression event the pressure diagram seems to show a reduction in the induction of induced air, and then followed by a 'snap shut' inlet valve where compression normally starts to build in the cylinder. Although I'm not sure on that engine code, I'd think the hydraulic valve adjuster dome shaped end sits into the rocker assembly, and this could be where you are seeing a problem?

victor2k
TwoWaves
TwoWaves
Posts: 337
Joined: Thu Jan 28, 2016 7:17 am

Re: MINI N16 engine Rough idle.

Post by victor2k »

Hello,
Try to disable the variable valve lift control,also the camshaft timing control and make some new captures.
I think :) you have a variable valve lift control event in your capture.
Please add (VIN/some details about engine) for your car in your post.
Best regards

waterfox11
Newbie
Posts: 3
Joined: Thu Aug 09, 2018 4:46 am

Re: MINI N16 engine Rough idle.

Post by waterfox11 »

OKay, I Will try it.
Thank you for your help.

grunf1976
OneWave
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Posts: 44
Joined: Tue Dec 15, 2015 3:05 pm
Location: Belgrade, Serbia

Re: MINI N16 engine Rough idle.

Post by grunf1976 »

Hi,
I had few of those. In all cases it were the valve seats. Common fault on those. When the engine gets hot head expands enough for valve seat to starts moving.

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