whats the proper way to just test the ford coil with a voltmeter?
testing ford coil on plug
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OVERKILL
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If it is misfiring, swap the coil with another on the engine and see if the misfire follows the coil.
If it does, replace the coil.
If it does, replace the coil.
it doesn't stumble all the time.i used a volt meter.i think i found the culprit but i don't know yet.i did change plugs and fuel filter...it was needed to be done.
The VOM thing is fine but coils that have issues can hide them well and may only show up at higher temperatures.
+1 Overkill, move the coil and see if the miss follows the coil.
+1 Overkill, move the coil and see if the miss follows the coil.
One more vote for move the coil. Your ohmmeter does not test resistance at kilovolt pot. If you don't have easy access to a scan tool to ID which cylinder has the misfire, then the spark plug will tell you unless it's a very infrequent miss. If this still doesn't work, try swapping in a coil borrowed from another vehicle or purchased new. Before purchasing new, ask the store clerk if you'll be able to return it if it isn't needed.
If you're dead set on using a ohmmeter, use an autoranging meter that reads into the megaohm range. Measure between the terminals and also each terminal to the spring that contacts the spark plug. Don't look for a value that matches the OEM specified range (yes there is one) because you can't count on that. Look for one reading where all but one coil reads within 15% of the others but one coil is way off like maybe more than 90%. That would constitute a fail. Done this way you won't get a false fail, but might get a false pass.
You _can_ use an oscilloscope for a more reliable test than a ohmmeter but only while the misfire is actively occurring.
If you're dead set on using a ohmmeter, use an autoranging meter that reads into the megaohm range. Measure between the terminals and also each terminal to the spring that contacts the spark plug. Don't look for a value that matches the OEM specified range (yes there is one) because you can't count on that. Look for one reading where all but one coil reads within 15% of the others but one coil is way off like maybe more than 90%. That would constitute a fail. Done this way you won't get a false fail, but might get a false pass.
You _can_ use an oscilloscope for a more reliable test than a ohmmeter but only while the misfire is actively occurring.
Originally Posted By: Kruse
If the coil has an open, or possibly a direct short, a DVM might find it. If the coil has some high-voltage arcing, you probably can't find the problem with a DVM.
As already posted, move it to a different cylinder.
The coolant pipe leak swamped #6. The miss was intermittent so I doubted that I could check the primary or secondary resistance with any luck.
Test by substitution.
If the coil has an open, or possibly a direct short, a DVM might find it. If the coil has some high-voltage arcing, you probably can't find the problem with a DVM.
As already posted, move it to a different cylinder.
The coolant pipe leak swamped #6. The miss was intermittent so I doubted that I could check the primary or secondary resistance with any luck.
Test by substitution.
The real way to test it is by doing a real time power balance test and then a coil stress test on the IDS. Then do the compression test through the IDS for giggles to make sure it isn't a dead hole.
yonyon,i have a new coil when i put the clip from my volt meter on one of the pins and the other on the spring the newone showed 6.8 all the other coils showed the same the one on the #4 cylinder showed a 5.5 i figured this one was the bad one.
For a civilian with limited access to high tech diagnostic tools, the coil swap idea is great and almost fool proof.
already tried but that means it will take several days to find it.stumbles were intermitant so far i been correct no stumbles...these coils are 11 years old so i will replace all of them eventually...
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