3-Cyl. VW Fox 2007 TDI - Timing right ?

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3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby terbo » Sat Dec 06, 2014 3:05 pm

Hi,

Maybe someone has a Waveform to compare for a VW Fox from 2007.

I don´t know if the timing is right.The Car starts and runs but it runs poorly.
One Cylinder is not doing what it should , believing the Scantool.
Compression looks "strange" in the startup, but then it seems o.k

Didn´t find a waveform on the Libray so far.

Greets Chris
Attachments
fox3.psdata
Timing check BNM Engine
(2.25 MiB) Downloaded 166 times
foix-tdi2.psdata
Relativ compression
(474.59 KiB) Downloaded 136 times
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby KimAndersen » Sun Dec 07, 2014 10:16 am

Hi there,

One thing I came across when I looked at your waveform capture was the shape of the signal from the crankshaft position sensor. As you can see on this picture - there are some disturbance in the signal, which i think you should look a little closer at.

CPK_SENSOR_PROBLEMS.jpg


Regards
Kim
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby terbo » Sun Dec 07, 2014 3:09 pm

Yes, i noticed that as well, but i don´t have any idea
what that could be. There is not faultcode for the sensor, the
OBD-Values look straight and its to regular and fast that i think
it doesn´t have anything to do with the "missing" Cylinder.

If someone has a smart idea what that is, or how to narrow it down ?!

I just was told that the Camshaft was replaced, because of some wear,
but the bad running was there before as well, so did not change anything.
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby tode » Mon Dec 08, 2014 11:10 am

For me the problem is somewhere else, the noise on the signal crankshaft is not a problem, I would check with compression and scann tool drift correction and injectors.
Regard.
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby terbo » Mon Dec 08, 2014 11:40 am

Compression Gauge says 32bar at all cylinders....
Meets what the relative compression looked like.

Injector Balance für Cyl. 2 is at -2,99 and Cyl. 3 is at + 2,99.

Swapped the Injectors 3 > 1 , values the same - Cyl. 3 seems
to do nothing.
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby Chris C Stahl » Mon Dec 08, 2014 3:42 pm

Hi
I have this file of a 2004 vw tdi T Vin #M I wonder if they are the same?
VW2 (3).jpg
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby tode » Mon Dec 08, 2014 4:13 pm

If I'm not mistaken, in the database on-line there should be a signal vs crank cam for this car, unfortunately I do not have now connected Pico scope and do not have access, but you can try.
A correction of + - 3 is not small, it remains always on cylinder 3 the problem could be mechanical, maybe an intake valve that does not open well, how come you have changed the cam? Inadequate lubrication or many miles?
You can cpntrollare the work of the valves with signal MAF, engine idling, channel scope in AC, scale amplitudes 1V or 500mV and time base 20 ms or 50 ms and checks if the pulsations in the intake manifold are correct.
Regard
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby terbo » Tue Dec 09, 2014 8:11 pm

Cam was changed because the owner "read about it on the net"
and bought one, and brought it in and wanted the old one changed.
He was told that the old one didn´t look bad but he wanted the new one in.
O.kk, so in with the cam, but problem stayed...

I will see what comes up, the next days it will stay at a bodyshop,
it gets some paintwork done...

When it´s back the project goes on...

Good idea - the MAF reading will be next i think.
Next up would be incylinder pressure...
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby Steve Smith » Wed Dec 10, 2014 9:47 pm

Hello and thank you for sharing these posts.

Regarding the noise present on the crankshaft signal, it is also evident (just) within the camshaft signal.

I have attached an image of the psdata file posted above indicating the events taking place in each cylinder.

The noise is most likely as a result of "high frequency current switching", in our case diesel injector.

I have seen this noise in other vehicles that run with no issues.

The maths channel indicates the change in RPM relative to the compression and power strokes.

Could you take a look and see if you agree. It would be great to get this vehicle back in for further testing and hopefully gain a fix
Attachments
3 CYL OVER VIEW.jpg
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Re: 3-Cyl. VW Fox 2007 TDI - Timing right ?

Postby terbo » Thu Dec 11, 2014 6:15 pm

Hi,

VERY NICE Info...looks fantastic.
Yes i think you are totally right with the noise coming from injectors.
Would make total sense.
Would like to get a good running one to compare to in hands,
but they are not so often engines...

I hope to get it on hand when it gets back....keep you posted.
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