2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

If you are not a PicoScope user and want advice with a diagnostic problem then post here. Forum members may be able to help.

2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby terbo » Sun Jan 25, 2015 6:42 pm

Hi,

Friend bought a used VW Golf a few weeks ago, that now has a Misfire.
He called me because Engine was running bad ONLY at idle, but really fine
over 1500 rpm, On the Highway you would not think it had any problem.
But soon the MIL turned on, and his hope it only came from long standing time turned off :)

So we looked at the Scan-Data - ECU told us "Cyl. 2 Misfire detected".
We swapped the Coil from Cyl. 2 to Cyl. 1 and the plug from Cyl. 2 to Cyl. 3.
Erased the codes an stared it up.....a few Min later , same trouble Code.

So out with the Fuel rail, and swapped the Injector from Cyl. 2 > Cyl. 4.

And again, clear codes, start-up, wait a few moments and - "Cylinder 2 Misfire detected" :(

Then we picked the Pico, to see things we didn´t want to see :)

Relativ Compression with Sync on Cyl. 1 Coil showed it already :(
Then I did 2 In-Cylinder Pressure readings...the ECU and the Relative Compression were right.

Maybe one of you can see anything to narrow down the cause...

Why does Cyl. 1 (O.K) only draw 350mbar vacuum (after the compression peak)
and the bad Cyl. 2 with only 7,4bar compression draws about the double (about 600mbar) ?

Is there a clue to what is failing ?

Thx Chris
Attachments
Compression Z2.psdata
Cyl. 2
(518.2 KiB) Downloaded 172 times
Compression Z1.psdata
Cyl. 1
(551.35 KiB) Downloaded 146 times
Relative Compression.psdata
Relative Compression with Sync
(1.71 MiB) Downloaded 149 times
terbo
User
User
 
Posts: 46
Joined: Sun Jul 06, 2014 2:40 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby Liteace » Sun Jan 25, 2015 7:43 pm

Hows cam timing and valve gear all good ?
Liteace
Guru
Guru
 
Posts: 145
Joined: Fri Jan 27, 2012 12:25 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby tode » Sun Jan 25, 2015 7:52 pm

If you want to know if the problem is a piston or an elastic band, uses sensor wps500 with maximum resolution and controls the pressure of the engine block (crankcase ventilation), from oil dipstick hole, the pulsations caused by blow-by must all be equal, if a is higher is because of elastic bands or piston that did not seal.
These engines should have a slight depression in the cylinder block caused by depression in the intake manifold, which could decrease the reading of the blow-by simply disconnecting the tube from the intake manifold.
If this test you are all ok, the problem should be only in the head, perhaps a self-adjusting that does not work well, or cams damaged or burnt valve if the valve, self-adjusting cam or suction you can always check pulse with wps500 manifold apirazione, if you find a higher peak burnt valve that does not close, if lower peak, cams ruined or log-blocked drain. :D
tode
User
User
 
Posts: 42
Joined: Fri Jun 20, 2014 6:59 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby terbo » Sat Jan 31, 2015 6:11 pm

I took a few more Waveforms from Exhaust,Intake,Dipstick and running Cylinders.
But the files are to big to attach, and i didn´t find a way to make them smaller.
I put the in one Archiv, maybe someone takes a look or knows how i can
get them Forum-acceptable ?!

I think one or two Valves are bad....maybe someone can explain witch and
how to see that in the Waveform.

http://workupload.com/file/QCxTiKhd

Here are a few Pictures from the Data :

Image
Image
Image
Image
Image
Image

Thanks
Chris
terbo
User
User
 
Posts: 46
Joined: Sun Jul 06, 2014 2:40 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby tode » Mon Feb 02, 2015 9:15 pm

The test dipstik, shows that you do not have problems of piston rings, also confirmed by the fact that does not smoke for oil consumption, pressure testing exhaust, you confirm that you have in the cylinder 2 poor combustion, look at the picture:

mancate accensioni_.jpg
Misfire


The abnormal shape of the wave indicates a different pressure of the exhaust gas, the classic puff you hear when the engine runs irregularly, the downward curve indicates that the combustion is poor and the pressure / temperature is low and the valve opening exhaust c 'is little boost of gas, while when the piston reaches PMS has fresh air with much volume that pushes out quickly, justifying the high ridge (puff exhaust)

mancate 2_.jpg


How to calculate which cylinder is?
The spark of the cylinder 2 (trigger signal CH 2) takes place with a slight advance with respect to PMS, then the cil2 is in compression, but we are looking unloading .... so that curve we see is the exhaust of the cylinder 3 if you count in firing order 1 - 3 - 4 - 2 here is that you find the cylinder with poor combustion.

Up to here everything OK, what I do not understand is the signal pressure in the intake manifold, if you have taken the lead coil always on cyl 2 seems that a pressure peak is instead caused by the cylinder 4, as if its valve aspiration was burned, but the proof is incopatibile with exhaust gas and the fault detected with diagnostic expect if some else has better reading than mine.

intake_.jpg


I hope I explained, my English is poor.
greetings
tode
User
User
 
Posts: 42
Joined: Fri Jun 20, 2014 6:59 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby terbo » Tue Feb 03, 2015 9:29 pm

Hi,

Thank you so much.....i just learned a hugh amount !
Just great !

Why the last Waveform doesn´t confirm the Cyl. 2 i can´t unterstand,
because that i suspect Cyl. 2 i think i triggered all Files of that Coil and just moved
the other Channel to Dipstick,Intake and Exaust.

If i could, i would just for testing do a new test just to verify the picture,
but Engine is at a friend of mine and the Head should bw on the way to the
machineshop already....
terbo
User
User
 
Posts: 46
Joined: Sun Jul 06, 2014 2:40 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby terbo » Sat Feb 07, 2015 8:46 pm

Quick Pic of the cause....Cyl. 2 (Exaust-Valve)

Image
terbo
User
User
 
Posts: 46
Joined: Sun Jul 06, 2014 2:40 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby tode » Sat Feb 07, 2015 9:58 pm

Terbo Thanks for the photo, I hope someone can explain to us the wave form in the intake manifold "strange" caused by an exhaust valve burned. :?:
greetings
tode
User
User
 
Posts: 42
Joined: Fri Jun 20, 2014 6:59 pm

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby KimAndersen » Sat Feb 07, 2015 11:07 pm

Hi Terbo

I would like to compliment you, for taken this subject to the end.

There is much to learn by following a diagnostic problem from start to the end and at the same time showing us the root cause of this strange compression problem with a picture.

Regards
Kim
KimAndersen
Guru
Guru
 
Posts: 148
Joined: Fri Nov 30, 2012 2:53 pm
Location: Denmark

Re: 2006 VW Golf 5 - 1,4 BCA - Cyl.2 Misfire

Postby terbo » Sun Feb 15, 2015 4:13 pm

The Engineshop told us, that this problem is common for 3 things :
- old (faulty) Software on the Engine ECU
- not optimal quality valves
- little oil burning because of city-driving only and carboned oil rings

We will see, the software was updated lately (but maybe to late) , there
were no oil-problems in last years seen, so maybe just the Valve Problem.

Hope it will run now for the next 200 000km ;)

Greets and Thanks

Chris
terbo
User
User
 
Posts: 46
Joined: Sun Jul 06, 2014 2:40 pm


Return to Help me fix my car

Who is online

Users browsing this forum: No registered users and 0 guests