Opel Vectra C Z18XER compression waveform doubt

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liviu2004
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Opel Vectra C Z18XER compression waveform doubt

Post by liviu2004 » Sun Feb 03, 2019 8:22 pm

Hi all,

Did anyone measured the cranking compression waveform for an Z18XER engine?

Got this car with misfire and poor running / idling. I believe injectors clogged, but have a look on the waveform. I've never seen a second pressure dip in the intake stroke.

Any thoughts?
Attachments
z18xer.png

kona
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by kona » Sun Feb 03, 2019 10:04 pm

Hi,

Influence Camshafts Adjusters. (If the accelerator pedal has not been pressed ?)

Try repeat measurement at IDEL.

Technician
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by Technician » Mon Feb 04, 2019 7:14 pm

Not normally any adjustment possible to the valves, they are hydraulic tappets. The compression is low by 4 to 6 bar. The intake depression is not recongised within the trace, pointing towards the inlet valves not opening correctly during the intake stroke.

liviu2004
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by liviu2004 » Mon Feb 04, 2019 8:08 pm

@kona, it will be no other measurement. I was wondering if anyone else’ve seen this before. Again, that is engine off, cranking, pedal to the metal.
You say that second dip is because of VVT. I tend to believe that, but I am not 100% sure.

liviu2004
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by liviu2004 » Mon Feb 04, 2019 8:09 pm

@technician, what intake dip with throttle fully open and cranking speed 200rpm?

kona
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by kona » Mon Feb 04, 2019 8:12 pm

Technician wrote:
Mon Feb 04, 2019 7:14 pm
Not normally any adjustment possible to the valves, they are hydraulic tappets. .........
To make you understand :
Attachments
2019-02-04_220439.gif

kona
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by kona » Mon Feb 04, 2019 8:26 pm

liviu2004 wrote:
Mon Feb 04, 2019 8:08 pm
..... I was wondering if anyone else’ve seen this before. .........
Yes. Right. With throttle fully open and cranking.

Technician
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by Technician » Tue Feb 05, 2019 1:33 pm

kona wrote:
Mon Feb 04, 2019 8:12 pm
Technician wrote:
Mon Feb 04, 2019 7:14 pm
Not normally any adjustment possible to the valves, they are hydraulic tappets. .........
To make you understand :
Sorry for confusion, I was not referring to the VVTi unit(s) when I said not normally adjustable. I was referring to the valve clearances, which are normally hydraulic buckets operating with a zero lash clearance.


seafordmotors
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Re: Opel Vectra C Z18XER compression waveform doubt

Post by seafordmotors » Mon Feb 11, 2019 7:17 am

This posted compression waveform is correct. Nothing wrong with that, Look at the uploaded waveform f a Z18XER performing OK
Attachments
Holden Astra AH Z18XER cranking compression No 3 Cylinder OK.psdata
(1.5 MiB) Downloaded 125 times

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