Polo 6N 1998 1,4 AKV-Engine Low Compression

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Re: Polo 6N 1998 1,4 AKV-Engine Low Compression

Postby Fat Freddy » Mon Mar 28, 2016 3:39 am

We can see the cylinder is good.

Measuring time between 0 psi gauge and TDC. All cylinders except 2 measure in excess of 14ms. Cyl 2 reads less than 11ms.
The cylinder spends more time/degrees in vacuum showing it's asthmatic.

HTH
FF
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Re: Polo 6N 1998 1,4 AKV-Engine Low Compression

Postby Fat Freddy » Mon Mar 28, 2016 4:11 am

tode wrote:If the test with WPS sensor in the intake manifold has given negative results, the problem of your car is a relief valve damage, from Z2-1 file it is clear that the lack of exhaust bag because the pressure rises quickly, a test, confirming, my idea is a test with 500 WPS in the exhaust pipe.



IMO the "exhaust bag' shows the that the cylinder has leaked. The down stroke of the cylinder pressure should match the upstroke as close as possible.

The reason for no bag is because the cylinder was capable of holding the lower pressure it reached so it matched the pressure to start with. While the other cylinders produced a higher pressure because of the % fill of air, the cylinder leaked more. There fore once the piston reached the same position on it's down stroke the finish pressure was lower than the start pressure.

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Re: Polo 6N 1998 1,4 AKV-Engine Low Compression

Postby tode » Mon Mar 28, 2016 6:55 pm

Fat Freddy wrote:My wild stab is a problem with the inlet valve of #2.
Cylinder pressure goes way below inlet manifold. No air entering engine.
Nothing to compress, so low compression.
High cylinder vacuum drawing oil into the cylinder and pumping it out.

But Hey! Chuck an engine in.


Hi FF for me the problem is on the exhaust valve, if the problem was the intake valve with wps sensor he could see the back pressure.

Fat Freddy wrote:IMO the "exhaust bag' shows the that the cylinder has leaked. The down stroke of the cylinder pressure should match the upstroke as close as possible.

The reason for no bag is because the cylinder was capable of holding the lower pressure it reached so it matched the pressure to start with. While the other cylinders produced a higher pressure because of the % fill of air, the cylinder leaked more. There fore once the piston reached the same position on it's down stroke the finish pressure was lower than the start pressure.


My English is bad, but I think I understand you
When the piston descends after TDC must generate the maximum vacuum possible, if little breathing, depression is more not less.
The test is performed at cranking, is normal to find a great depression when the inlet valve opens and after the 360 °.
For me is not correct depression (after tdc 0 °) because just after the 110 ° the pressure rises quickly even if both valves are closed.
I think that with the WPS sensor in the exhaust can view the problem.
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