measurement of secondary ign voltage is a bit odd

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measurement of secondary ign voltage is a bit odd

Postby joscorstjens » Sun Aug 22, 2010 6:00 pm

My investigation started because my rpm-gauge was fluctuating heavily . It is connected to the wasted-spark ignition coils through 2 diodes and a zener diode on a pinto 2.0 injection engine.
I just measured cyl 1 secondary voltage (through capacitive pickup picoscopeprobe) which is going all over the place (from 1.5 up to > 20 kVolt) while the current through the primary coil is quite constant (from 4 to 7 amp) depending on the amount of dwell (2.3 to 4.4) I put in.
The attachments contain a view of the combined current and voltage reading on picoscope 4223 (third attach) the other two show a zoom of a lower voltage ignition spike.
The .psdata file seems too big to attach.
This pattern is similar on all 4 cylinders.
Injection and timing is ok and the car runs fairly well but a bit 'irregular'.
So what could be the cause of this?
Attachments
20100822-0001-badscale2.gif
20100822-0001-badscale1.gif
20100822-0001-curvol2.gif
joscorstjens
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Re: measurement of secondary ign voltage is a bit odd

Postby joscorstjens » Sun Aug 22, 2010 6:03 pm

... and here is the view with the unzoomed signal
Attachments
20100822-0001-curvol1.gif
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Re: measurement of secondary ign voltage is a bit odd

Postby elijah » Wed Oct 06, 2010 7:10 am

joscorstjens wrote:My investigation started because my rpm-gauge was fluctuating heavily . It is connected to the wasted-spark ignition coil through 2 diodes and a zener diode on a pinto 2.0 injection engine.
I just measured cyl 1 secondary voltage (through capacitive pickup picoscopeprobe) which is going all over the place (from 1.5 up to > 20 kVolt) while the current through the primary coil is quite constant (from 4 to 7 amp) depending on the amount of dwell (2.3 to 4.4) I put in.
The attachments contain a view of the combined current and voltage reading on picoscope 4223 (third attach) the other two show a zoom of a lower voltage ignition spike.
The .psdata file seems too big to attach.
This pattern is similar on all 4 cylinders.
Injection and timing is ok and the car runs fairly well but a bit 'irregular'.
So what could be the cause of this?


Hi there! You seem to have a lot of knowledge under the hood. I'm really quite impressed by your graphs and terms. I'm a newbie so I honestly don't understand some of them. Anyway, I'm just wondering if you were able to solve your fluctuating rpm-gauge? Any updates about this because my friend is also encountering this kind of problem but a bit different. His rpm-gauge would go delay sometimes so we're kinda confused why is it like that. Do you have any opinion about that?
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