Odd Pico Plug Captures

Does your lead have a ground on it?

Yes

Doug, If this system has a dist and a coil wire then you best signal will be picked up at the coil wire. The scope will pickup all cylinders in a parade. To ID the cylinder in question, use another channel to connect a secondary, or actual trigger pickup, to cylinder #1 and reference the firing order data.

CH A is the secondary lead on the coil wire and I'm doing a brake torque. CH B is the primary coil winding voltage. CH D is a sync probe on the cyl 1 plug wire. The Sample interval should be set to 1 us to scope ignition. Use 500ms/div and 6 MS.

The inside the cylinder event is extremely lean. Also, several of your plug lines are above 18KV. Is this idle speed? Either way, the high KV demand points to a VERY lean issue. I haven't seen that pattern in years. My memory fails me as to just what is wrong. You can find Mac Van DenBrink on You Tube in his EXTREMELY knowledgeable “Through The Eyes Of The Scope” I think he teaches that example…

I remember the old black secondary ignition leads that came with the old picoscope kits would do that. Then they came out with updated secondary ignition leads that were colored (blue, red, green, and yellow), and that was supposed to fix that problem. I don't know if the updated leads did indeed fix it, because I still have the old black ones that came with my kit when I purchased it long ago…

Yeah I've been using older Hantech leads. I need to purchase some Pico ones!

Steve, you appear to be referring to the Autonerdz colored leads that have different attenuation. Pico only offers black secondary leads in my experience.

I ordered one and will be updating on any difference. Yes it is black.

Oh, I didn't realize it's an Autonerdz product. Do you have them? Are they working good for you?

I'm happy with them so far. Can't say I'm an expert with ignition though. I bought them a year ago after watching Spence De'Corde's Group Therapy presentations on Secondary Ignition. He shows the difference between the Pico Secondary leads and the Autonerdz colored secondary leads…how he prefers the colored Nerdz leads due to less wandering on the voltage line. Spence shows how the wandering is…

I recently purchased a new blue pickup lead and have a capture now of both leads and the differences I will show soon.

Yes Sherman I think I've watched him before I will look him up thank you!

MAP at 5.7 Hg. is way too low. You said PSI? These later models had a high rate of intake gasket failures.

Yah it should be at least 10 to 16 right? Last year I checked for intake leaks but didn't find anything! I forgot to check the fuel trims but will do that, Thanks Glenn.

Hi Doug, During a cold start, use a spray bottle of water and spray the intake mount areas with a stream of water. Watch for excess steam coming out of the tailpipe and listen for a possible gurgle/ sucking sound. These intakes are bad about leaking and have to be torqued exact when replacing intake plate style gaskets. Ultimately, it may need an intake replacement. The 5.3 and 5.7's also had…

So the actual vacuum is 18.5 to 19.5 psi. So I need to get another MAP sensor! Fuel trims are good. And it didn't take much to kill the motor by sucking on the MAP sensor!

Hi Doug, That sounds like a MAP or bad line going to it. Usually a MAP should test good at 18-20 Hg of vacuum from what I have seen.

Here is the misfire updates although it is empossible to see anything worth anything with these poor captures! 4, 5 and 6 were misfiring a lot. I will present a capture after I receive the new secondary Pico pickup lead.

There is at least one cylinder that repeatedly has no spark arcing across the spark plug's air gap. Do not use secondary leads on distributor type ignition system plug wires. Use the secondary leads on DIS plug wires. Compare all of the plug wire KVs and all spark plug burn times using the coil wire secondary or the primary coil winding voltage. Purchase a Trigger Pickup Inductive Lead to…

I do have one of those inductive clamps also. I was wondering if they woukd give a better picture or not. I'll have to try that. Thank You for your time!

So the other one is capaciive pick up and was wondering why it doesn't work so well on distributor wires?

Another method to find cylinder 1, is to ground the cylinder 1 plug wire, with a jumper wire. In the coil wire secondary parade, you'll see 1 plug wire with low kv demand. Another method is to connect the GM ST125 coil output/spark tester into the end of the cylinder 1 plug wire. Or use an adjustable spark tester set to 25kv and the cylinder 1 secondary will show higher kv demand with a…

Thanks Ray. But at idle I can see number one spark. But I do need to play with the adjustable spark tester to see the difference in the KV of the coil for practice

My alternate method of locating the cylinder 1 will still work at all rpms and under all loads.

If you are using the black secondary ignition leads, they will do that. I have had the colored leads do that on rare occasions. usually relocating the pickup on the wire will help

Those colored pico leads aren't clip over secondary leads are they?

The Autonerdz coloured secondary Pico leads will clip over the DIS secondary cables,

And they are superior to the black leads correct? And shoo you have a link to that please?

Doug, the pico leads with the clip also have a box at the base of the clip - it is 10,000:1 calibration. The picture of the leads in Ray's post are 1000:1 The colored leads are available in 9 different colors and the clip is designed to work with larger wires and down to 8mm. If you are worried about the lifting of the signal clipped to #1 plug wire, the best and ideal option is to use an actual…