Opel Corsa C Z14XE doubts about ignition primary signal

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liviu2004
TwoWaves
TwoWaves
Posts: 472
Joined: Sat Mar 19, 2016 8:23 am
Location: Netherlands

Opel Corsa C Z14XE doubts about ignition primary signal

Post by liviu2004 »

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!

Technician
TwoWaves
TwoWaves
Posts: 705
Joined: Thu Apr 24, 2014 8:32 pm

Re: Opel Corsa C Z14XE doubts about ignition primary signal

Post by Technician »

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.
-->
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.