2010 VW Golf 1.4L TSI Compression Leak

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2010 VW Golf 1.4L TSI Compression Leak

Postby AdvTechTS » Wed Jul 19, 2017 4:03 pm

Hello, I have a 2010 VW Golf 1.4L TSI in the workshop with a Compression Leak in cylinder 3.
It is only really noticeable at idle.
The engine ECU is picking up the misfire and logging #3 misfire codes.
No evidence of previous overheating issue, one owner and 160,000km on the clock.

Spark Plug and coil was swapped with cylinder #4 and the fault stayed with #3.
I used my smoke machine and could not find a leak
I used shop air to do a cylinder leakdown test and I can't find fault with the valves or rings
So I tried a running cylinder analysis which confirms cylinder leakage but I wondered if anyone out there with a sharp eye might be able to read more than I can see.

My suspicion is a faulty pressure seal on the #3 direct injector??? It is located at the back and below the intake and is impossible to see...

I have upload 3 waveforms:
#1 - Cylinder #4 - good comparison
#2 - Cylinder #3 - low compression
#3 - Cylinder #3 with Cylinder reference #4 imported

If anyone can see anything in the waveforms that I can't it would be greatly appreciated.
Attachments
Volkswagen_Golf_2010_20170719-0003.psdata
Cylinder #3 with Cylinder reference #4 imported
(9.06 MiB) Downloaded 210 times
Volkswagen_Golf_2010_20170719-0002.psdata
Cylinder #3 - low compression
(8.67 MiB) Downloaded 157 times
Volkswagen_Golf_2010_20170719-0001.psdata
Cylinder #4 - good comparison
(8.81 MiB) Downloaded 141 times
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby STC » Wed Jul 19, 2017 4:59 pm

Here is the swerve ball - If you cant find the leak with shop air on a cylinder leakage test then perhaps there is no leak !!! ???

Back to your theory
I cannot see anything either other than the obvious compression peaks are lower on #3. Hopefully someone will come along with a better analysis than me.

In the meantime I would say that the leak is not via the valves. That would show up in the scope capture for sure ???
If it is running past the rings then your WPS in the Dipstick will see that.

That only leaves the leak being sideways through the gasket or past the injector - Or does it ???
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby victor2k » Wed Jul 19, 2017 7:23 pm

Hello,
Try to record the exhaust pressure,carter pressure(a lower pressure for cyl 3 will confirm the leak at the injector seal).In fact both tests will confirm the leak at the injector seal...do not forget to apply the delay for 4 cylinders engine for pps!
Also check again the moments of opening/closing of exhaust/intake valves in the attached capture...I think is too late :)
Also the peak at 360^ make to look again at the camshaft wear/exhaust lash adjuster.
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby STC » Wed Jul 19, 2017 9:06 pm

Victor

Try to record the exhaust pressure, carter pressure(a lower pressure for cyl 3 will confirm the leak at the injector seal).In fact both tests will confirm the leak at the injector seal

You refer to two tests - what is the second one ?

I can't see how measuring exhaust pulses will confirm the Injector seal leak. That "leak" (if it is a leak) appears to be at higher combustion pressures, a time when the exhaust valve will closed.

Exhaust gas pressure will of course confirm a cylinder down, which we already know. Synced to an injector or coil we can establish which one(s)

I am still hung up about the fact that Cylinder Leakage Test with Shop Pressure didn't reveal a leak.

AdvTech
What pressure is your shop air ? What pressure did you load the cylinder up with ? How long did it hold pressure
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby victor2k » Wed Jul 19, 2017 9:25 pm

STC wrote:Victor

Try to record the exhaust pressure, carter pressure(a lower pressure for cyl 3 will confirm the leak at the injector seal).In fact both tests will confirm the leak at the injector seal

You refer to two tests - what is the second one ?

I can't see how measuring exhaust pulses will confirm the Injector seal leak. That "leak" (if it is a leak) appears to be at higher combustion pressures, a time when the exhaust valve will closed.

Exhaust gas pressure will of course confirm a cylinder down, which we already know. Synced to an injector or coil we can establish which one(s)

I am still hung up about the fact that Cylinder Leakage Test with Shop Pressure didn't reveal a leak.

AdvTech
What pressure is your shop air ? What pressure did you load the cylinder up with ? How long did it hold pressure

:D Back to the first post...some misfires was recorded at the 3 th cylinder.Before to check other things I will record using PPS /WPS500 the exhaust pulse/pressure.I think is the easy way to confirm misfires...
Also I think a misfire will give a lower cylinder pressure.Also the leakage at the injector will give a lower pressure(In exhaust and carter)...more can be find checking on the engine.
Last edited by victor2k on Wed Jul 19, 2017 9:36 pm, edited 1 time in total.
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby STC » Wed Jul 19, 2017 9:31 pm

In exhaust and carter


What is Carter ?
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby victor2k » Wed Jul 19, 2017 9:39 pm

STC wrote:
In exhaust and carter


What is Carter ?

wps measuring the pressure instead of the oil dipstick. :oops:
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby STC » Wed Jul 19, 2017 9:51 pm

Understood.

So that will only confirm or deny Ring Blow By ??? Never nail a Injector seal leak !
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby victor2k » Wed Jul 19, 2017 10:26 pm

STC wrote:Understood.

So that will only confirm or deny Ring Blow By ??? Never nail a Injector seal leak !
Ok,but is only your opinion...
and let me tell you why:
a lower compression (without a leaking at intake, exhaust or at the rings) will be accompanied by a lower escaped pressure in intake,exhaust or carter. :|
But again I will see first at the attached image(at 365^ after TDC the exhaust and the intake valves are closed!).
Attachments
Untitled.png
Last edited by victor2k on Wed Jul 19, 2017 10:49 pm, edited 1 time in total.
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Re: 2010 VW Golf 1.4L TSI Compression Leak

Postby Technician » Wed Jul 19, 2017 10:33 pm

Am I reading the scope data correctly!!

Compression pressure between 77 and 88 psi !!

Manufacturer minimum spec I see is 150 psi
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