Secondary ignition testing.

Ask for and share advice on using the PicoScope kit to fix vehicles here.

Secondary ignition testing.

Postby mastertech02 » Thu Dec 08, 2011 12:56 pm

I have been attempting to carry out ignition tests on the following vehicle but cannot get an accurate display of secondary ignition patterns ?

Vehicle BMW E38 750i 2000mdyr

This vehicle is a V12 engine with a control unit for each bank and also has a distributor and set of leads for each bank.
The vehicle had a misfire and i was attempting to trace the cause.

I used the Automotive presets and leads as recommended .
(swapped leads in case defect ,but have never been used)

Removed rodent protection from ignition lead to ensure correct fitment of secondary ignition sensor pp178.
Using the following.

Automotive-Ignition-Distributor-Secondary Distributor (kinglead)
Followed connection procedure but no trace displayed ?
Then
Automotive-Ignition-Distributor-Secondary Distributor(Plug lead)
No Trace displayed ?

Then
Automotive-Ignition-Distributor-Primary vs secondary

Primary trace displayed with obvious fault occurring. A very intermittent secondary trace appearing.
Fault with Ignition lead or Pico measurement ?
Moved Seconday ignition sensor pp178 to another ignition lead and same happening.

Attempted on other bank of cylinders as comparison =Same.
No positive result for secondary ignition .

Attempted setting up by selecting channel A =Secondary ignition probe and Selecting various KV scales. Still no reliable trace displayed from plug or king lead ?

Ran out of time from a customer point of view and Renewed Bank 1 Cylinder 4 ignition lead. Which has fixed the missfire issue and Could be seen on primary trace but no reliable secondary.

Am i missing something or can any one tell me a set up to use in future for reliable measurement ?

Any help please
Regards
Dennis Carey.
mastertech02
User
User
 
Posts: 13
Joined: Thu Jun 30, 2011 10:55 pm

Re: Secondary ignition testing.

Postby Lee » Thu Dec 08, 2011 3:25 pm

Hi Dennis

It sounds like what you are seeing here is the 'Signal' is not meeting the 'Trigger Threshold'. You can correct this by simply lowering the 'Yellow Diamond' thats in the middle of the screen.

We have had a few instances where the current trigger is set 'Too High' and we have started to correct this by re-capturing the presets and changing the Trigger 'Type' and the 'Threshold'.

For now just lower the 'Yellow Diamond' and you should get the signal as shown in the Help Files and shown by the preset.

Keep checking the Software page for new versions to download as this fix will be released soon in which all the Secondary Presets will be revised.

I hope this helps

Kind Regards

Lee - Automotive Technical specialist :D
Lee
Advanced User
Advanced User
 
Posts: 79
Joined: Fri Feb 19, 2010 10:36 am

Re: Secondary ignition testing.

Postby Dave Hill » Mon Dec 26, 2011 10:12 pm

Hi Dennis

My personal view is that you should avoid the reliance on Pico's Automotive Pre-sets as often as possible.

In this instance, I would recommend that you forget any triggers, but instead change your "collection time" & put 20 seconds total screen time.

Assuming that you have your volt range set correctly, the only other consideration should be your "Samples" setting. Make sure that this is cranked up high enough, so that you capture enough detail. You can easily check this, by zooming into the fine detail to make sure that you have smooth detail in your coil oscillations.

I have an example somewhere, taken from a 750, where I scoped ignition primary on one bank, whilst using the front cylinder "secondary" (on the same bank) as a means of identifying the firing events.

The pre-sets are OK, but they should only be considered to be a rough starting point (in my opinion at least)
Dave Hill
User
User
 
Posts: 39
Joined: Fri Jun 22, 2007 8:15 am

Re: Secondary ignition testing.

Postby mastertech02 » Thu Dec 29, 2011 2:25 pm

Hi Dave.

Thanks for spending the time to give a reply.

I will take these tips on board when next checking primary/secondary.

Regards
Dennis
mastertech02
User
User
 
Posts: 13
Joined: Thu Jun 30, 2011 10:55 pm


Return to Diagnostic discussion

Who is online

Users browsing this forum: No registered users and 0 guests