Cylinder #1

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Cylinder #1

Postby nickyy » Sat Mar 22, 2014 6:34 pm

Sorry for the newbie question, but here goes:

I just got a 4-channel picoscope with Mixmaster and I've set up a parade of secondary ignition patterns from my car's spark plugs. It appears that the parade is constantly moving across the screen, so how can I tell which is cylinder #1? Is there a way to stop the parade and just have four images "fixed" on the screen?
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Re: Cylinder #1

Postby Steve Smith » Mon Mar 24, 2014 11:59 am

Hello Nicky and thank you for your enquiry. To prevent the pattern/waveform moving about your screen you will need to set a "trigger" to stabilise the waveform. Here is would be helpful for you to use the pre-set below.

"Using the AUTOMOTIVE menu. Select AUTOMOTIVE-IGNITION-DISTRIBUTER-IGNITION SECONDARY (PLUG LEAD)". This will set your scope to capture a stable secondary ignition signal from the mixmaster......

Remember the Mixmaster must be earthed via the 4mm banana socket at the lower left of the Mixmaster front panel and please make sure the internal battery voltage is correct.

Connect your first ignition pick up lead to number 1 BNC socket (trigger) of the Mixmaster front panel marked “Bank A” and connect the clamp of this pick up lead to the ignition HT lead of number 1 cylinder. (This is your trigger signal as well as the ignition pattern for number 1 cylinder)

This will enable you to capture 1 x ignition signal due to the time base set by your scope pre-set. Here you will need to select a 20ms/div time base to view more ignition signals from the Mixmaster depending on how many pick up leads you have connected to “Bank A” of the Mixmaster.

Moving your trigger icon to the left of the screen will allow you to see all the ignition signals displayed across your screen span of 200ms, after the initial ignition trigger of cylinder number 1 is captured.

Now you can then use the firing order to determine which ignition signal belongs to which cylinder knowing you have triggered the scope using cylinder 1. I hope this helps? Take care......Steve
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Re: Cylinder #1

Postby nickyy » Mon Apr 07, 2014 9:19 pm

Steve,

I've been playing with your recommended setup for several hours. Some questions have arisen:

1) I connect the channel A cable from the Mixmaster to the scope's Channel A. Then connect the trigger to D.
The A1 on the Mixmaster is connected to Cyl #1 and the rest follow along bank A. At the bottom of the Pico screen, in the box next to trigger (set to auto) only channel A shows up? Why? (I have had channel D show up on a couple of occasions but I can't reproduce it.)

2) Once the parade appears, I move the yellow diamond to the left-most spark line and let the recording take place. Once I stop the recording, how do I know which is #1 since the yellow diamond is moveable, i.e. during playback the yellow diamond seems to stay on the left side of the screen.

3) I can only see three waveforms on the PICO screen. What do I have to adjust in order to see all?

Thanks,
Nick
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Re: Cylinder #1

Postby Steve Smith » Tue Apr 08, 2014 2:26 pm

Hello Nick and sorry for my late reply
Using the Mixmaster I would not use channel D for an input, could you try the method below?
1. Connect the BNC channel A cable from the Mixmaster to the scope's Channel A
2. Connect an ignition pick up lead to BANK “A” No.1 on the Mixmaster and number 1 HT lead. (This will be your trigger)
3. Connect the remainder of your ignition pick up leads to the relevant cylinders and to BANK “A” BNC sockets 2 to 6 if measuring up to 6 cylinders.
4. Ensure the Bank select switch is set to “A” only
5. Use the pre-set as described above but increase your time base to 20 ms/div
6. Drag your trigger icon (Yellow Diamond) to the left of the scope screen to view all firing events on one screen
7. The trigger is set only for channel A only as channel D is not used and so the option will not be available
8. Run the scope and the engine and you should now see up to 6 x ignition events on channel “A” only, with the trigger on number 1 cylinder and the remainder following on from left to right in the vehicle firing order.
Regarding “how do I know which is #1 since the yellow diamond is moveable, i.e. during playback the yellow diamond seems to stay on the left side of the screen”
When reviewing waveforms in the buffer, they are displayed exactly how they were captured and displayed on screen. The trigger icon will still be identified on the waveform in the buffer in the form of a “greyed out” diamond. Once you identify the ignition signal containing the diamond (trigger) you will have identified number 1 ignition event and again, continue from left to right after the trigger in the vehicle firing order to identify the remaining ignition events
I can only see three waveforms on the PICO screen. What do I have to adjust in order to see all?
If you have the Mixmaster connected as above using Bank A only, connected to Channel A on your scope with the Bank select switch set to A only, then all ignition pick up leads connected to the Mixmaster should be displayed in a parade formation on channel A.
Can you check your time base is set to 20 ms/div (200ms across the screen)?
Can you ensure your ignition pick up leads are connected correctly and in good order?
Can you confirm the Mixmaster is earthed correctly at the front panel?
Can you confirm the Mixmaster battery is in good working order?
Does the vehicle misfire because of a HT fault-hence no ignition event on screen?

I hope this helps but please feedback if not

Take care……Steve
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