ZR-1 Net Registry Forums - View Single Post - Rough Running

Paul Workman · 08-05-2021

I've nothing to add to your conclusions or decisions: I'd be doing something similar.

However!! (and you did touch on this too), HIGH VOLTAGE devices can frustrate attempts to "OHM" them out using the standard DVOM/VOM. And, the reason (in case some are wondering) is high voltage can punch through (arc!) insulation that has cracked or deteriorated/weathered), or current pushed by high voltage can take a surface route to ground, especially if the surface is covered with moisture or salt or rust...any number of impromptu conductors. And, frankly the standard VOM is powered with (at most cases) 1.5 or 9 volt battery(s - neither being high enough to cause arching/shorting and thus being detected by the VOM.

To directly test/measure stuff like wire insulation or continuity requires a tester such as a MEGGER (a high voltage "VOM" used for measuring the resistance of insulation or spark gaps).

However, I doubt you'll ever see a MEGGER at your local auto parts store: would be unusual if you did! So, much as I HATE indirect testing, substitution with a known "good" device may be the next best alternative. But, here's the rub: How do we know the replacement is any good? And, HERE is the place where so many times ppl get in trouble: they ASSUME the 'new' device is good, and therefore if the problem persists or returns shortly thereafter, they don't verify the issue is not withe the new part. (See how often in threads like this where someone says: "It can't be (this or that) because it was just changed a short time ago!" The most failure prone time for a new device is immediately (or soon thereafter) it is first put in service!! Never assume a new part is not bad based on time in service...NEVER! Verify operation.

NOTE: And, since so many parts come from over seas, the trend is a lot of (electrical especially) parts just don't last like the OEM parts if they work at all! Just sayin.

08-05-2021	#14
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: Rough Running - Ignition Coil out? I've nothing to add to your conclusions or decisions: I'd be doing something similar. However!! (and you did touch on this too), HIGH VOLTAGE devices can frustrate attempts to "OHM" them out using the standard DVOM/VOM. And, the reason (in case some are wondering) is high voltage can punch through (arc!) insulation that has cracked or deteriorated/weathered), or current pushed by high voltage can take a surface route to ground, especially if the surface is covered with moisture or salt or rust...any number of impromptu conductors. And, frankly the standard VOM is powered with (at most cases) 1.5 or 9 volt battery(s - neither being high enough to cause arching/shorting and thus being detected by the VOM. To directly test/measure stuff like wire insulation or continuity requires a tester such as a MEGGER (a high voltage "VOM" used for measuring the resistance of insulation or spark gaps). However, I doubt you'll ever see a MEGGER at your local auto parts store: would be unusual if you did! So, much as I HATE indirect testing, substitution with a known "good" device may be the next best alternative. But, here's the rub: How do we know the replacement is any good? And, HERE is the place where so many times ppl get in trouble: they ASSUME the 'new' device is good, and therefore if the problem persists or returns shortly thereafter, they don't verify the issue is not withe the new part. (See how often in threads like this where someone says: "It can't be (this or that) because it was just changed a short time ago!" The most failure prone time for a new device is immediately (or soon thereafter) it is first put in service!! Never assume a new part is not bad based on time in service...NEVER! Verify operation. NOTE: And, since so many parts come from over seas, the trend is a lot of (electrical especially) parts just don't last like the OEM parts if they work at all! Just sayin.