Shrink Stretch reference timebase

Ask any questions about using PicoScope Automotive software here.

Shrink Stretch reference timebase

Postby andrewbishop66 » Tue Mar 29, 2016 9:42 pm

Im trying to overlay 4 in cylinder waveforms using cam signal as the sync but the waveforms are during cranking and the times are different so I cant align them as i would like am I missing something or is it not possible
I did find a post for a feature request back in 2014 but nothing else

Thanks Andrew
andrewbishop66
User
User
 
Posts: 38
Joined: Wed Jan 20, 2016 10:16 pm

Re: Shrink Stretch reference timebase

Postby FioranoCars » Thu Mar 31, 2016 11:04 pm

Hi Andrew
What is your time base ?
Can you post a capture (psdata file)?
Cranking can lead to wildly different speeds of rotation verse hot idle which can be quite consistent if all is well ...

Sorry but when you say in cylinder is that pressure?
If your are overlaying 4 separate captures, then I'm speaking hypothetically as not tried this, but I'd set the time base to cover from slow to fast rpm, say 120 to 480, 120 being 2 compressions per second, so 2 seconds to cover all 4, and allowing for cam phase offset and where you place the trigger, call it 5 seconds to cover trigger and 2 cycles, so 500ms per div.
If cranking bear in mind that you might need to try a few captures per cylinder tested to avoid bad starter offset (IE early inertial issues). And may be if you have 4channels add an amp clamp 600/2000amps...

Ok, could have misunderstood completely, but if you want to overlay 4 crank pre start captures, you need to ditch some as cam will trigger will lead to some slower or faster inertia rates or set time base longer, say 1s per div. trigger as single, and review each.

Might be persistent trigger would help, but with cranking, it might not, never tried this, sorry!

Please explain more and post what you've got ... Probably misunderstood your needs, let me know :D :D

Best
Richard
User avatar
FioranoCars
Guru
Guru
 
Posts: 189
Joined: Thu Dec 13, 2012 11:26 am
Location: London, UK

Re: Shrink Stretch reference timebase

Postby volrem » Fri Apr 01, 2016 12:53 pm

I think this is the same request that was talked about in this thread: post42041.html?hilit=shrink#p42041


And yes I also really want this feature.
volrem
Guru
Guru
 
Posts: 146
Joined: Fri Jan 03, 2014 3:43 pm
Location: Estonia

Re: Shrink Stretch reference timebase

Postby andrewbishop66 » Fri Apr 01, 2016 6:32 pm

Thanks for the replys
Will post some files when on other laptop but just as Volrem has pointed out thats what I wanted

it was in cylinder pressure one from each cylinder I was trying to confirm that the timing was correct on a peugoet 307 with GDI 16 Turbo engine which refuses to produce a spark unless told to by diagnostic system and one injector pulsing in time with cam and crank. Id been told that the cam lobes can move round on this engine so just trying to confirm that tdc was in the right place

I have to say my problems seem minor to some of the things you guys deal with

Thanks Andrew
andrewbishop66
User
User
 
Posts: 38
Joined: Wed Jan 20, 2016 10:16 pm

Re: Shrink Stretch reference timebase

Postby volrem » Fri Apr 01, 2016 7:23 pm

Four different cylinders with different speed. It would be so easy to align these with stretch/shrink timebase option.

Sorry forgot to add filter. By the way it would be great if we could apply filter on reference waveform also (after reference is created).
Attachments
reference.png
volrem
Guru
Guru
 
Posts: 146
Joined: Fri Jan 03, 2014 3:43 pm
Location: Estonia


Return to PicoScope 6 Automotive software

Who is online

Users browsing this forum: No registered users and 0 guests