Primary ignition waveform

2001 Accord 3.0 Customer describes what sounds like a misfire. No codes and drives good for me. Dont feel any misfires. Primary ignition looks like this on all 3 front bank coils. 3 rear bank coils looks more like what the sample waveform looks like on the test information. The firing line starts before the voltage drops all the way down. Front 3 the voltage drops past the starting point and all the way to zero then comes back up for the firing line. Are the front 3 coils bad or is this nothing to worry about?

Just to be clear, sir, is this the part that you're noticing?



Also, I believe you're looking at the coil control signal in the first channel? I'm inclined to say that it's nothing to worry about, just want to make sure I'm looking at it right.

Yes that's what I'm talking about. The voltage goes down then comes back up. The other 3 coils don't do that. Didn't have much time to look at it tonight. Plan on driving it more tomorrow

When a problem is on the difficult to access cylinders I always get that sink feeling that somebody in the past has been cutting corners. Chances are you are going to end up pulling the rear plugs and coil packs and visually examine and play swaptronics.

I suggest looking for carbon tracking and inspect spark plugs for electrode damage.

I know this is of no help and I'm sorry for that but every time I set the scope up to 50ms it makes me laugh so maybe you can get a laugh too!



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Also I wouldn't bother looking at primary ignition unless you have a dead miss or your corresponding events with cylinder 1 firing .secondary ignition is where you'll see anything useful when it comes to misfires but even then it can be hard to spot a bad 1

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bruce.oliver wrote: Yes that's what I'm talking about. The voltage goes down then comes back up. The other 3 coils don't do that. Didn't have much time to look at it tonight. Plan on driving it more tomorrow

OK cool. I'm thinking along the same lines as Andy, having mixed OE and aftermarket coils at work. Or, intermixed spark plug brands/types. Dunno if it's related to your misfire. :lol: But that's where my money is.

Ben wrote: Also I wouldn't bother looking at primary ignition unless you have a dead miss or your corresponding events with cylinder 1 firing .secondary ignition is where you'll see anything useful when it comes to misfires but even then it can be hard to spot a bad 1

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It's a 3 wire coil, they have the ICM built in to each coil. I couldn't get my COP probe to pick anything up. I've heard that some people put a plug wire between the coil and plug but I didn't try that.

I couldn't duplicate the complaint anyway so not 100% sure it was a misfire.

Ah I hate it when you can't get secondary off of the coil by the time you pull the coil to put the jumper in you mise well just inspect the boot and the plug ....

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