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Explain the physics behind an intermittent misfire.

Winchested said:
Ya shit gets hot then doesn't work. It's not rocket science.
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So it gets hot, doesn't work for 1 cycle, cools down from not firing one time, and proceeds to keep working for 20, 50, 100 times more before getting hot enough again to not work 1 more time? Where is the science?

I could talk and listen about the concept of a heat-related issue but it would be details and on a microscopic level. If you have a crack where the threshold for failure is almost at an atomic level, then the tiniest fraction of a single degree of temp could make that gap big enough for a single failed event, and that failed event would decrease that temp by the tiniest fraction of a degree that puts it back into function where it would require many instances of firing to drive the temp to failure mode again, only to fail 1 time and repeat.

What about computers and microchips? That's all magic and I expect it to remain a mystery.



I appreciate the folks that gave their genuine thoughts on the subject.
 
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In terms of heat affecting a control unit, sometimes it is as simple as a bad solder joint. Where a chip, relay, pin, whatever component is soldered to the board. If they went light on the solder then it could be very thin and like to break the solder or wiggle loose.

I had a home audio amp that quit working. Googled the issue, turns out it was a common issue with bad solder joint on the MOSFET chip. The fix was to blast it with a heat gun and it would melt the solder back into the joints. After I did that it was fixed and worked for another 5 year until I gave it away. But this circuit board was older and was pretty large with big chips so you could actually see the solder joints. On a ecu/pcm/dme whatever you want to call it, those components are going to be teeny tiny and I doubt any repair possible, just replace.

I have a motorcycle that has the ecu mounted close to the exhaust, and over time the engine randomly stalls. Turns out it was a common issue with my specific model and has a bad solder joint that acts up when hot. But the fuckin case is packed full of epoxy and you cant take it apart to get in there and do anything. Just have to replace it
 
Yota Up said:
Never threw plugs and all that at it. Why would you think that when the first thing you see is a bad wire?
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Because of the 2nd sentence in your opening post of having hit exactly that list of shit. God damn you're dense. Then you post up pics of the arced out plug wire, but you're all vague about everything and "you're good on fixing it". So is it a game of you already found the problem and you want to play if anyone else can speculate on it with minimal information and not seeing the truck, or are you genuinely asking for help figuring it out? Because all your follow up posts read like option A in which case I'm out.
 
I thought this guy was trolling. Actually I think he still is 🤣
 
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