Vectra c 2.2 misfire

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Vectra c 2.2 misfire

Postby Burfd » Mon Aug 31, 2015 6:33 pm

Good people of the forums I'm in need of help please.

I have a vectra-c 2.2 petrol z22yh engine and i have a eml on for P0304 cylinder 4 misfire. prior to coming to me its had new plugs, coil pack and injector's although I'm told the injectors were second hand off a known god car.. now i have dabbled with picoscope a few years ago and just this last week found myself getting reacquainted but I'm puzzled by my findings on these injectors could you take a look and see what you think, side note i also actuator tested the injectors and no difference noted in engine running i.e still missing when tested as the other 3 made a notable difference, and when i ohms tested them at the multi plug i got 1.8ohms on each

am i doing something wrong when testing ??

thanks for any help or advise
Attachments
cyl4 idle 2 secs later.png
cyl 4 on idle
cyl4 idle.png
cyl 4 on idle two seconds later
cyl3.1 idle 3 seconds later.png
cyl 3
cyl3 idle.png
cyl 3 3 secs
cyl2 2 secs later.png
cyl 2
cyl2 idle.png
cyl 2 2secs later
cyl1 idle 3 secs later.png
cyl 1
cyl1.png
cyl 1 3 secs laters
Burfd
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Re: Vectra c 2.2 misfire

Postby Autonerdz » Tue Sep 01, 2015 4:03 pm

This is Gasoline Direct Injection system right?

If so, what you are seeing there looks normal to me.

I am not familiar with this application but typically GDI manipulates both sides of the injector. If you are only looking at one side, then you are not seeing the whole picture. Voltage is typically applied to a bank of injectors, and only one in that bank is activated on the other side. Therefore, you will see the voltage supply trace for the bank even when it's not that injectors turn to fire.

So...you see voltage pattern with no 'work' or current flowing.

Try this:

Place channel A on the high side of the injector and B on the low side. Place the current probe on C. Make sure your channel grounds are on battery negative. Use attenuators on A and B. Now get plenty of capture time on the screen. Once you get a capture, use a math channel A minus B. This will show you the voltage drop across the injector.

When you examine the result it will all be clear to you. 8)

Tom Roberts
The Picotologist
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Re: Vectra c 2.2 misfire

Postby Burfd » Tue Sep 01, 2015 8:07 pm

Thanks very much for the reply, I will be out of the workshop for the next couple of days but I will be sure to have a go on my return and post my findings. Thanks again for the help

Oh just to note yes this is a petrol GDI.

Thanks

Burfd
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Re: Vectra c 2.2 misfire

Postby Burfd » Wed Sep 16, 2015 8:02 pm

Really sorry for the super late reply, I've been flat out busy.... but have some news on this problem.

In short another vectra came in the shop almost a perfect match!! i thought bonus ill check the injector pattern on that car and got the exact same pattern.... that got my grey matter going and well i thought its back to basics time, plumbed in the VAC gauge and boom timing issue highlighted so i then removed the cam cover and check the timing marks... and yes its jumped.

So once again i have found myself jumping in too deep straight off the bat having listened to what the previous tech had done.... instead of starting at the start.

So i must apologise guys for time wasting..... Sorry
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