BMW E92 2009

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BMW E92 2009

Postby RS-4 » Tue Sep 20, 2016 9:41 pm

Hallo,

motor N43B20A difficult to start, no idle and when motor runing cca. 200 rpm I hear misfire. I thinks the COP secondary go to ground ... but all 4 ?!

Can someone help me in diagnosis waveforms? It's strange waveform...

blue chanel - all 4 COP

red chanel - cyl.1-cyl.2-... primary

Thanks and regards.
Attachments
IMG_20160920_155237785.jpg
IMG_20160920_155515976.jpg
cyl.4.psdata
cyl. 4 primary + current of all 4 coil
(637.09 KiB) Downloaded 34 times
cyl.3.psdata
cyl. 3 primary + current of all 4 coil
(612.73 KiB) Downloaded 22 times
cyl.2.psdata
cyl. 2 primary + current of all 4 coil
(697.94 KiB) Downloaded 19 times
cyl.1.psdata
cyl. 1 primary + current of all 4 coil
(1.07 MiB) Downloaded 22 times
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Re: BMW E92 2009

Postby STC » Wed Sep 21, 2016 6:00 am

Indeed, crazy waveforms.

Could you try an amp clamp on the common supply or earth to Coils, same with injectors and then Crankshaft and HP Fuel.
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Re: BMW E92 2009

Postby victor2k » Wed Sep 21, 2016 6:52 am

Hello,
Monitoring primary I think there isn't autoinduction sometimes,also freq(b) have some strange variations
Replace cop and repeat the test on cyl 1.
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Untitled.png
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Re: BMW E92 2009

Postby steevegt » Wed Sep 21, 2016 10:09 am

The first think I would look it will be for crank and cam signals. It looks like the coils are firing randomly.

The low induction spikes, I believe are caused by the very low sample rate (20ks/s). Try to increase it...
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Re: BMW E92 2009

Postby RS-4 » Wed Sep 21, 2016 1:33 pm

Hei,

thank you for your answer, tomorrow I get a new coil and spark plugs so I'll make a recording.

Regards
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Re: BMW E92 2009

Postby steevegt » Wed Sep 21, 2016 8:45 pm

Sorry, after a second look, the coil firing doesn't look that random actually, especially if you look at the current ramps at lower RPM (~1000 rpm). I can't say that they are "on time", because I don't have a similar engine to compare (maybe in pico library, didn't check), but I guess the timing between fires and the number of fires in this system may be normal...

But, as I have said before, because of the low sample rate (20 ks/s) I believe we can't conclude anything from that primary ignition waveform.
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Re: BMW E92 2009

Postby victor2k » Thu Sep 22, 2016 7:53 am

Hello,
In my opinion the marked firing voltage is a misfire event(the firing voltage isn't at drop of coil curent,a short burning time,but at 700 us after we have strong oscilations?)
And 20 Ks/s will give a resolution at 100us,enogh for the analyze of firing voltage and spark line.
Of course a higher sample rate is good but the saved file will be too large...
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Untitled.png
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Re: BMW E92 2009

Postby steevegt » Thu Sep 22, 2016 10:31 am

It may be a misfire event, I don't know...

20 ks/s will give a 50 us resolution, that is not enough to give a clean firing voltage.

If you measure the peak event time, like in the example from pico, that event will only last for 15 us, at most. I have checked in some primary voltage readings I have made, and the 15 us stands.
Obtaining the peak voltage with 20 ks/s is a probabilistic event. You have a 30% chance to just make a measurement inside that 15us window. Obtaining something close to the peak voltage, It will have a much lower than that probability.

If you want, for instance, just 5 poins to draw that peak, you will need to have a resolution of at least 3 us. 17 times more than the 20ks/s.
Attachments
primary_voltage_peak_time.PNG
Primary voltage peak time window
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Re: BMW E92 2009

Postby victor2k » Thu Sep 22, 2016 11:17 am

Hello,
Thank you for the firing voltage explanation...is the first time when I see this event recorded at high sample rate :D
In many ignition diagnostic manuals I see scope with settings at 20-50v/div and 1ms/div for primary voltage waveform.
Back to the topic:inspect if the spark plugs is ok,not matter if is new or not(wrong spark plugs,faulty spark plugs)
Also try to register total(short+long fuel trim) or injectors curent.
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Re: BMW E92 2009

Postby RS-4 » Fri Sep 23, 2016 3:29 pm

Hi guys


Here I am again. I'm still fight with BMW. Mounted the new coils and spark plugs but without success...


Then I made a test injectors and finally ...


As soon as I mounted the new injector I will continue with waveforms.


I also saw that compression is not good but we'll see how it will work with the new injector.
Attachments
compresion 1.psdata
(492.28 KiB) Downloaded 24 times
VID_20160923_154244232.mp4
Injectors
(25.27 MiB) Downloaded 27 times
A all 4 coil B primary cyl.1.psdata
New COP (all4)
(938.2 KiB) Downloaded 26 times
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