Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

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Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby terbo » Sat Sep 03, 2016 5:59 pm

Hi,

A friend got this 2006 VW Polo with 1,2 BMD Engine.
After the MIL starting coming and the car did not run right he took it to the shop.
They changed Coils, Plugs, the Valves , Headgasket and Timing Chain.
But the problem is still present. No one could precisely say when the Problem
happens, you can drive it for 100km without one miss, you can fly 25km at WOT
at 4500 rpm with 150km/h over the Highway, no problems, but here and then it
just misfires on cylinder 2. Then you stop, cycle the Ignition and it runs again without
any problems, till it does it again.

I tryed all day and now i found out, it does ist repeating if you are at about 3800-4000rpm
for a few seconds, then it misfires....

I scoped what i thought could be it, but i don´t see a reason why it shuts of the injectors....
What should i scope out to get behind this Problem ? Or do you see something ??

Any help is welcome...
Attachments
Volkswagen_Polo_2006_Petrol_20160903-0001.psdata
Polo cut out at 3900 rpm
(12.37 MiB) Downloaded 31 times
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby STC » Sun Sep 04, 2016 12:25 am

Remove amp clamp from Injector and place it on common V or Earth for Coil(s) Primary and post the wave form.
And take a good look at the Valve Springs on Cylinder 2.
Thanks
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby terbo » Sun Sep 04, 2016 10:36 am

Think this is what you meant...
Took it from the fuse Box Feed.
Feeds the ECU as well, but getting to a other common wire was not
easy to do.

Swapped the coils ans the Injectors from Cyl. 2 to 1 and 3 - always drops Cyl. 2.

I think its the ECU failing....

[url]https://ecu.de/vw-(volkswagen)/motorsteuergerät/simos3/volkswagen-vw-03d906033f-siemens-5wp40298-104637.html[/url]

They know this problem with 1 Injector cutting out....
Attachments
Volkswagen_Polo_2006_Petrol_20160904-0001.psdata
Cut Out with Coils
(9.32 MiB) Downloaded 32 times
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby STC » Sun Sep 04, 2016 11:42 am

Think this is what you meant...

Yes, I wanted to see what dropped out first, Coil, Injector or Compression. Unless you have a wiring fault then I agree - ECU.
Open it up and follow the pin back to the Driver/Mosfet and scope all three pins.

You have 2 Known Good to compare with.
STC
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby terbo » Wed Sep 07, 2016 7:06 pm

Got a used ECU for 20 Bucks....put it in, adapted it,
drove it, and :( :( :( Same error.....Even if it it used, the chance that
a second one has the exact same problem on the same Cylinder at the same
rpm Range, i don´t think is very likely.

Would there be a chance of seeing anything with the WPS500 in Cylinder,
without spark/fuel in the Cylinder at that RPM ?
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby dieseljohnny » Wed Sep 07, 2016 9:35 pm

These gave trouble with valves, Valve guides.

You say headgasket was replaced...
Was the head checked when it was off?
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby STC » Thu Sep 08, 2016 12:26 am

And a compression test at Cranking speed is not realistic and doesn't reveal much. A dynamic compression would give it away WPS 500 in cylinder test as above would nail it.
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby Fat Freddy » Fri Sep 09, 2016 11:44 am

I agree with STC. A cranking compression will only ever show a bad engine, never a good one. All to do with volumetric efficiency of the valve train relative to engine RPM.
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby steevegt » Fri Sep 09, 2016 4:14 pm

Sometimes a leak down test can detect problems that a regular compression test doesn't. You can try that...

The best, I agree, is looking at a running compression waveform, as suggested before.
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Re: Polo 1,2 3-Cyl. 2006 BMD - Cylinder drops out

Postby terbo » Sun Sep 18, 2016 9:32 am

Today i took some waveforms at different RPMs,
from Cyl. 1 (no misfires) and Cyl.2 (shutting off).

Maybe anyone sees a cause - i don´t.

If i messure peak to peak, then i get always only half of the real rpm
in the bottom right corner from the Pico-SOftware, is that normal ?
Attachments
Cyl2.rar
Cyl2 Waveforms
(5.2 MiB) Downloaded 13 times
Cyl1.rar
Cyl1 Waveforms
(3.75 MiB) Downloaded 11 times
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