cliffyk

Grab some heavy sewing needles/pins from a woman in your life, grease 'em up lightly and then stick them through the wires--connect to the scope probes to the pins.

You can "back-probe" the connectors if you have some skinny probe tips, however hanging on the probes and playing with the scope adjustments is a PITA...

Hangwire

Hey cliff just wanted to let you know I probly wont get around to checking these COPS until after work today or tomorrow. Kinda really busy at work so I gotta take a short lunch(yay).

But a quick question.....I assume when you say the yellow/green ground wire and red wire you are referring to the wires that go into the COP clip?

I have a pretty fine point probe that I think I can easily just poke through to the red wire with. But seeing as the ground is a clip and not a probe, I will probably have to use a needle like you suggested? Push the needle into the wire, then clip the ground onto it?

I did find a nicer digital oscilloscope at work its a Tektronix TDS1012. At a quick glance I didnt see anything regarding a "HF filter" what should I look for regarding this? What will it say on/around the button/switch? Somebody here at work could probably explain it to me but I figured since i'm posting i'll ask. I assume "HF filter" means High Frequency Filter?

cliffyk

Yes, the red wire on all the COPs is connected to a fused +12V source.

The other wire (light green/yellow on COP #5) is not technically a ground, however it is switched to ground by the PCM during the "dwell" period to charge the coil--the same way that the points in a conventional ignition system would conenct the coild to ground when they closed.

The COP fires when that ground connection is opened and the built-up magnetic field in the core collapses.

Yup, that's all

On a TDS1012 press the Trigger Menu button, then select Coupling using the menu buttons to the right of the display, and then HF Reject.

Hangwire

Your the man, cliff.

cliffyk

Here's another trace of what you can expect to see:



This is also my '03 GT at idle, but captured with an OWON HDS-1022M-N hand held 'scope--a nice little instrument. It's rated at 20MHz but easily handles signals out to 27MHz-- I use it now for most automotive stuff...


While we are talking about oscilloscopes, and for those who might give a rat's backside, here's what the O2 sensor output looks like at idle (the glitches are ignition noise):



You can see that the signal "switches" slowly, at 250mHz to 300mHz, between 0.22V and 0.97V.


And this is the IAC control signal, also at idle:



The IAC is normally held closed by an internal spring, and is driven by this 2.1kHz signal to make it open. The duty cycle (the time at +12V vs. time at 0.0V) of the signal is varied to keep the valve "hovering" around the desired opening.


I had captured these for a small tuning course I have been trying to put together...

Hangwire

When an IAC fails it fails mechanically right? Would I see anything through an oscilloscope that would indicate a failing IAC? My intake is making the I'm really effing hungry so i'm gonna growl noise.

May be Monday till I get to throw a scope on my cops, boss wasnt crazy about me taking the 'scope home over the weekend. Sigh.