Four wire COP current ramp

Ask for and share advice on using the PicoScope kit to fix vehicles here.
Post Reply
Darren Fraser
TwoWaves
TwoWaves
Posts: 54
Joined: Sat Jul 18, 2020 7:45 am

Four wire COP current ramp

Post by Darren Fraser »

Hi guys
I had a classic shorting primary wave form on cylnder three
on a 1az engine in a 2010 Toyota Noah today. Current went
straight up to 3 amps before starting to ramp up to 10 amps.
Swapped the coil with cylinder number one and the "shorting
primary" stayed in cylinder three. I measured the current on
the earth wire on all four cylinders and checked ign
voltage, IGF and IGT on all four cylinders which showed
identical wave forms. Has anyone come across this before?
Cylinders 1,2 & 4 give a really good current ramp wave form
but cyl 3 gives a 1/3 vertical line before the ramp no
matter which coil is used. I can't think of anything else
that would do this apart from a shorting primary?

User avatar
vasek
TwoWaves
TwoWaves
Posts: 106
Joined: Tue Feb 17, 2015 7:27 pm

Re: Four wire COP current ramp

Post by vasek »

Hi.
Need - the file with IGT,IGF,CURRENT.
It would be nice to see this exciting Thriller.
It's like in the new C.J.J.Nolan movie.
Everyone runs somewhere with a very significant view,but - backwards.))

Darren Fraser
TwoWaves
TwoWaves
Posts: 54
Joined: Sat Jul 18, 2020 7:45 am

Re: Four wire COP current ramp

Post by Darren Fraser »

Can't upload psd files yet from our old lady, I'll try and upload the Pico 6 software today. I'm also going to try and find the common ground or ignition to get all for ramps on one page.

User avatar
Autonerdz
TwoWaves
TwoWaves
Posts: 387
Joined: Wed Nov 20, 2002 4:19 pm
Location: Washington State USA

Re: Four wire COP current ramp

Post by Autonerdz »

I can't think of anything else
that would do this apart from a shorting primary?
While what you describe can be caused by a shorted primary, it often is not. Many things inside and outside the coil can cause the coil charging current to rise abnormally fast.
One of these things can be as simple as a fouled spark plug.

Darren Fraser
TwoWaves
TwoWaves
Posts: 54
Joined: Sat Jul 18, 2020 7:45 am

Re: Four wire COP current ramp

Post by Darren Fraser »

Thanks Tom. Yes, having done a bit more research, and evidence of a fouled plug caused by a hectic rich condition I agree. The ramp is due to CEMF and in my case, there must have still been energy in the coil between firing events which caused the "half ramp" which looked like the beginnings of a shorting primary. Unfortunately I don't have a COP paddle yet which would have verified this and I was unable to get a secondary waveform off of the primary due to the internal configuration of the coil. Thank you for your input Tom.

Oh for the day when we can afford all the necessary scope attachments!

Post Reply