Chevy Colorado misfire

John Sure looks like a connection problem from image. Can you post psd file? Im sure you checked but did you check coil connector on the coil with the scope at all with same results? The only other thing that comes to mind would be ckp input problem if coil connection is good or coil power and ground issue. I think your signal should look the same from ecm no matter of power and ground at…

Have you tried swapping coils? Maybe a problem with the coil primary circuit? Edit; i looked at some service information and cleared up my misconception that it was a 2 wire coil. with that being said i probably would've came to a similar conclusion, although i would've likely swapped the coils first due to the rare possibility that somehow the module in the coil was causing a problem and…

Plug shorted? We had one that burned the electrode off and then shorted inside. Was on a Ford but it messed up the primary signal.

John, measure the coil ground voltage. this is from an 08 Volvo XC 90 4.4 CH A COP 6 ground wire with 3.5v CH D COP 6 amps

If it makes you feel any better, I would have figured the problem was the ECM as well. Given that it didn't fix the issue, I'd guess that the pin fit on connector X2 pin 1 is loose. Edits: I don't see how a coil could cause that. The voltage pattern is switched power from the ECM measured directly at the ECM. If the coil had low resistance or was shorting to ground, the amperage waveform would…

… I'd vote for a coil fault ( and do swaptronics, if possible)…what about doing a wire overlay…maybe power a sealed beam halogen bulb with the control ckt isolated on BOTH ends ?… Dan H.

If that pattern repeats , then the signal from the pcm is being pulled down. The signal was never intended to be able to carry a load. Faulty coil. Similar to a 5 volt reference shorted to ground. HTH I bet if you put a microprobe on it , you will see an inverted V :)

Disconnect coil and see if trigger cleans up. I would assume you'll already tried swapping coils before springing for a new pcm?

First attempt, new Denso plug & coil. Second attempt swapped coils. Third try. ECM, In AM will try swapping coils and plugs one more time. Scope w coil unplugged and scope ground.I will see if I can grab a PSD file. Any chance a rub through would cause this. Not very repeatable but seems to happen more often in drive or reverse. Super erratic how often it happens too. Good times.

Yes either a loose connection or that #1 coil signal wire shorted(pulled low) would cause your scope pattern.

John, it looks like the low COP's primary coil winding's amperage draw is caused by a voltage drop in the power or the ground wires or the terminals to the primary winding. The low current draw thru the COP's primary winding is similar to low current draw thru corroded terminals to a dim headlight. Use wire piercing probes into the COP's B+ and the ground wire near the COP's connector and…

Just make your own ignition coil circuit control wire. Just for curiosity how look signal at ignition coil. Good luck

How often is the problem duplicated ? wiggle test ? It being a Chevy I would lean towards loose pins . like Tom Wilks said make your own wire circuit to rule out wiring issue . Don't get down on your self we all get bit at some point when battling the Beast .

weird graph to bad not spread out ,obviously coil is kicking when commanded …. I have no suggestion I'm sure you have done everything possible back probe everything right at the coil…. I wonder if that 1st post is correct a bad CKP trigger on 1 coil possible

I agree with Karl, this looks like a faulty connection or damaged connector. As it pulls more amps the connection breaks. You could overlay a new wire to test.

So….Put the scope away and went back to basics on this one. Problem was fairly intermittent, but when it did happen it would misfire for five to ten minutes. I swapped #1 and 2 coil while problem was happening (as many suggested} and issue went away. Hmmmm. Problem Has to be either a coil connector or wiring issue. Ran a test wire (once again many of you suggested) and the misfire has not…

Thanks for the update and which wire to the COP did you repair?

IC1 From computer to coil.