92 550sx spark issue

Joined
Jul 17, 2018
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Location
Alaska
#1
My 550 lost spark suddenly last week. I ohmed the coil since it has 20 volt on both the 2 wires going in. The ground ohmed out to 0. I'm not sure how to test the coil. Then I heard that you can't. While working on it I randomly got spark back for 30 sec. I assume it's a coil but cant find on to swap it out with to make sure....any ideas or more tests I can do the right way.
 
Joined
Jul 3, 2018
Likes
3
Location
seattle
#2
There are four 'coils' in a JS 550, charging coil, for battery, charging coil, for ignition, & trigger coil, all three packed on stator plate.
The fourth is in the E box, dual tower wasted spark CDI, each plug fires every time, once on combustion stroke, once on exhaust stroke.
Check your trigger coil for proper resistance (ohms) first.
 
Joined
Jul 17, 2018
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0
Location
Alaska
#3
How would I do this test. Power cycles at 20 volts to 0 and back at the coil in the cdi box. Wouldn't that indicate that coil is bag and the cycle of power show the trigger coil working.
 
Joined
Jul 3, 2018
Likes
3
Location
seattle
#4
You can check the integrity of the coils on the stator at the bolt on cap at the Ebox, just unplug the connector once you unbolt the cap,
green & green are the battery charge coil, the manual will tell you which wires run the other two coils, the other wires are red, black & gray.
The coil itself, i believe you measure between the high tension leads, the ones that attach to the spark plugs, if the resistance is off by 10%+,
the coil itself is considered no go. (bad). Just use an accurate meter when you do this, you don't want to buy pieces you don't need.
Also, I don't understand how you are getting 20 volts, the system runs off a 12 volt DC battery, the most volts you could get should be
13+ after the charging coil topped off the battery. You may also have a bad voltage regulator, not uncommon failure on 550s. : (
 
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