question about ignition coil resistance measurements
- Thread starter cityboy
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When you are dealing with an electronic ignition module, due to the semiconductor package that switches the primary, there is really no valid test that you can do with an ohm meter. Only positive troubleshooting is to replace it with a known good one.
I agree, but the challenge is to obtain a good one. Using those specifications certainly provides you with an indication of problems. Recently I returned two new Ignition modules, Primary : 129 ohms and Secondary 1.55 K ohm, which I bench tested and then installed. I confirmed that it was defective- no spark. It was made by one of the oems SEM . I am now awaiting another unit made by FHP Elmotoren, an oem which I found recently. The vendor tested it and photographed the results of his ohmeter which were promising. It may work.
Unfortunately most vendors will not provide you with test results of the part number, even if the part is made by an oem.
They typically go by the thought of a new part being good. And most people wont break a multimeter unless they have cause for an issue.
If customers ask for such results, and condition their purchase based those results, vendors may change their thinking. Otherwise, purchase and use return shipping labels based upon non-conformance to specifications if that is the case.
Ohm meter tests with these modules are so meaningless that it is irresponsible of the manufacturer to give the info and mislead anyone into thinking they are relevant.
Exactly, even if the readings are within those specs it doesn`t mean the module is any good or will work as in most instances its not the coil part of the module that fails, its the trigger chip embedded in the module that fails most often.
In the older points type ignition, it seems like the coils lasted forever, sometimes the capacitor would dry out but the coils kept going. Now with modern electronic ignition modules there is a high failure rate and, as just noted, most (if not all) are due to semiconductor failure in the electronics package that replaces the function of the points. The package switches the current in the primary and as heat is the real enemy of semiconductors, components that handle this current should be mounted on heat sinks but of course have to be packaged with the coil, so they are all potted together in epoxy which makes it difficult to dissipate the heat. The coils are mounted where they get the cooling air from the FW fan but after total lack of cleaning, they get packed in with nice insulating sawdust. A final insult to the coil is when the engine is shut off and the cooling air stops, the heat of the cylinder soaks into the coil and might be what kills it. Most people claim it was running fine when it was shut off and then would never start again. Progress is SO good.
Great post that is why I liked the old two piece electronic ignition .The coils very very seldom fail and you can use a module.Maybe I am a dinasoar but I have had chain saws that were used till they were worn out and they still had the original points. I have been running saws for 55 years and have never bought a set of points. I changed alot of sets in outboard motors but that was because we ran a fishing resort and it was faster and pretty well guarantied the motor would run well.I have come across a few bad caps over the years you can usualy tell the cap is bad if the points are burnt heavy on one side. Lots of times the motor will start and idle but will not rev.
Kash
Heat is the biggest killer of electronics in my hop
Kash
Heat is the biggest killer of electronics in my hop
