Opel Corsa C Z14XE doubts about ignition primary signal

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Opel Corsa C Z14XE doubts about ignition primary signal

Postby liviu2004 » Sat Jul 08, 2017 10:22 pm

Hi,

Help me understand this. My car, an Opel Corsa C 2002, petrol engine, Z14XE. I've played around with Pico for ignition secondary and primary. I thought my engine runs fine, however, I have doubts about cylinder 3 spark.

Can you please have a look to the ignition primary waveform, something does not look right to me.

Cylinder 3.png


Those are the rest of the cylinders, 1, 2 and 4 and peak voltages:

Cylinder 1.png
Cylinder 2.png
Cylinder 4.png
Peak voltages.png


Here I have the secondary waveform for cylinder 3:

Secondary cylinder 3.png


And cylinder 4:

Secondary cylinder 4.png


Fuel trims are ok, between 0-3%, nothing to worry about, engine runs acceptable to me, idle speed varies between 770 and 790 but nothing to be seen on dash.

It was dark when I stop with testing, so I plan to:
- visual inspect spark plugs on cylinders 3 and 4, eventually to swap them and have another go;
- measure fuel pressure system when injectors 3 and 4 are triggering, check how the waveform looks like for comparison, I have an WPS500X;
- in cylinder running compression?
- anything else?

A general impression how engine runs:


Thanks for help!
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Re: Opel Corsa C Z14XE doubts about ignition primary signal

Postby Technician » Sat Jul 15, 2017 5:00 pm

liviu2004 wrote:Hi,

Help me understand this. My car, an Opel Corsa C 2002, petrol engine, Z14XE. I've played around with Pico for ignition secondary and primary. I thought my engine runs fine, however, I have doubts about cylinder 3 spark.

Can you please have a look to the ignition primary waveform, something does not look right to me.

Cylinder 3.png


Thanks for help!


Let's just concentrate on the first scope trace.

What I'm looking at there is the intermediate section of the trace, e.g. after the coil winding's there is a blue voltage line with much fluctuation present, I could have said noise but that would be incorrect, so, this is what I think is happening;

After the arc at the spark plug has ceased there is always some energy left in the coil, this remaining energy is seen in the coil winding's as it dissipates away through the secondary circuit. The coil oscillations are also called 'Ringing', this is because of the coil action as it is pulsed.

Much of the information required is not shown on the scope trace, e.g. firing line, spark line, dwell section etc, so for a more detailed investigation I think a more detailed scope trace is required, but based on what I can see to date I think the intermediate section is not dissipating the coil energy away correctly for the next operating cycle.

Just an idea to think about.

Edit; added info

How good are those coil leads in the video, sorry I didn't watch that before, and how close together are those leads and pickups?

I've seen voltage traces like that before that were nothing more than badly positioned pickups and leads, try moving them around away from each other and see if the voltage patterns change any.

Just had a go on a Corsa at my place to look at the secondary traces, I would probably try another coil pack on your car as I think the secondary winding's look like they are shorting internally!

On the secondary coil winding's where the energy is dissipated my coils have four to five oscillations where yours have none.
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Re: Opel Corsa C Z14XE doubts about ignition primary signal

Postby STC » Sun Jul 16, 2017 11:22 pm

Can we see a CKP trace with Cylinder 1 Sync, O2 S1 and MAF or MAP Please. at Idle and 2500 rpm

How Coil Primary and Secondary behaviour can be a direct consequence of mechanical condition and fuel delivery.
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Re: Opel Corsa C Z14XE doubts about ignition primary signal

Postby liviu2004 » Mon Jul 17, 2017 12:49 pm

Technician: coil leads are brand new Pico, they are at 1st use.

Shorted coil pack while they do 30kV+? I seriously doubt your conclusion.

I do notice that cyl. 3 burn time is somehow smaller than rest of the cylinders. Also burn voltage 1-1.5 kV higher. Indeed coil oscillations are indicating some energy left in the coil.

My suspicions are on spark plug air gap or clogged injector.

Will provide more data at the end of the week, as I am away from home for a while.
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Re: Opel Corsa C Z14XE doubts about ignition primary signal

Postby Fat Freddy » Mon Jul 17, 2017 1:39 pm

I do notice that cyl. 3 burn time is somehow smaller than rest of the cylinders. Also burn voltage 1-1.5 kV higher.


That will go hand in hand. There are all these examples of bits of string and coil energy all over the net to demonstrate that. Try playing around with the plug gap and watch burn time.

HTH
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Re: Opel Corsa C Z14XE doubts about ignition primary signal

Postby Technician » Mon Jul 17, 2017 3:48 pm

liviu2004 wrote:Technician: coil leads are brand new Pico, they are at 1st use.

Shorted coil pack while they do 30kV+? I seriously doubt your conclusion.



Sorry my bad, I didn't open the scope file to read the KV scales, :oops:
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