Hi Folks,

I have this 01 Beetle 2.0 (AZG) in the bay with a very intermittent misfire on cylinder #1. I'm trying to get a secondary pattern but I get no clear picture. I guess there is something wrong with my settings, I can't figure out what. Please take a look at the attached screen shot.

Any suggestions?

Thanks,
-Kai-

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Kai,

I would probably want to see all the cylinders on four channels for comparison.

Tom Roberts wrote on Jul 27^th, 2010 at 8:51am:

Kai, I would probably want to see all the cylinders on four channels for comparison.

Thanks Tom,

All cylinders looked the same. Moved the pickup from cylinder to cylinder and tried all four channels. Used another lead, still the same picture. Found the USB cable chaffed. New cable and all is well now.

The intermittent mis turned out to be a bad ignition wire.

Thanks,
-Kai-

Kai,

Glad you got it sorted.  Feel free to post the data file for the after capture for everyone to see.

[quote author=436B626C6F7C0E0 link=1279636324/2#2 date=1280277451
The intermittent mis turned out to be a bad ignition wire.

[/quote]

I had one today with exactly the same fault,i was scoping 1&4 on secodary ignition for comparison,fault codes was misfire cyl1.

Whilst the scope was running i lost the plug KV on channel B  unless i changed the trigger to CHB then i lost the plug KV on CHA,if that makes sense ?

Any idea why this would happen ? Any pointers on scope set up for secondary ignition for one event or many ?

Cheers

Rob.

Robski wrote on Oct 23^rd, 2010 at 7:12am:

I had one today with exactly the same fault,i was scoping 1&4 on secodary ignition for comparison,fault codes was misfire cyl1. Whilst the scope was running i lost the spark KV on channel B  unless i changed the trigger to CHB then i lost the plug KV on CHA,if that makes sense ? Any idea why this would happen ? Any pointers on scope set up for secondary ignition for one event or many ? Cheers Rob.

HI Rob, I do have a couple of ideas and will post what I think you may have here... But my first question is which channel was on which as well as which channel was the trigger on when this happened?

Now if you were to have the trigger on the signal that dropped out, when the drop out occurs then your scope with stop as you mentioned above. When you switched your trigger to the other signal that did not drop out then the scope kept running and allowed you to see the signal that had the issue...

With that said... I would recommend you not trigger on a signal you consider an issue or leave it in free run and put more time on the screen, do the capture and then stretch it out.  

The choice would be if you wish to watch it as it is happening or need to be watching as you are trying to induce the failure...  Or if it happens without watching and can record and go back to review.

Hope that helps

Spence

Hi Spence

If i was triggering on CHA then i would not see the correct waveform for secondary on CHB & vice versa,CHA #CYL1/CHB #CYL4,i was wanting to catch the event on the missing #CYL1 so had 1&4 on the screen for comparison.I tried on different trigger settings & could only really get a good stable trace with repeat trigger.

I should have saved the waveforms but was a little busy,its no big problem i will have a play to see if i can see what i was maybe doing wrong myself,i did notice that when i was changing the timebase that sometimes i would lose the trace especially if i raised the revs  ?

I cant't remember though what time settings i had now,so my information is probably useless  :D

Cheers

Rob.

just to add at the start of scoping the 2 together i did see both spark lines perfectly,but because the traces were close together i am not sure if both plug KV's were visible,it wasn't untill i spread them apart that i noticed this ?

Rob.

Hi Robski
In your reply 6, you stated that you lose the trace if you raise the revs. Secondary kv lowers when rpms are raised so if your trigger is set high up on the kv, the KVs will go lower than where the trigger is set and you will lose the trace or the trace will freeze if you are at 50ms/div or less.


Ray

thanks Ray,noted  ;)

just had a play on my own car this morning based on the advice,i used split screen & also 1&4 traces on 1 screen,even gave rapid trigger a go.

Truly awesome tool,took 15 rapid triggers & could see close up the waste & power spark,did this also free running & on repeat trigger with more time on the screen to see more events.

Thanks for the pointers,hooking the Pico up is such a pleasure than my previous scope.

I love my Pico  :-*

Cheers
Rob.