# Stihl 028WB Coil Test



## InstantLegend (Jun 5, 2005)

Can someone please tell me the valid ohm ranges for testing the primary and secondary windings? 

Also, how long do you wait during the test? When I test the primary winding my meter goes down to 1.2 ohm instantly and then a few seconds later it goes to 1.1 and a few more seconds it goes to 1.0. I believe this value has to be 1.0 or less. Is this good or should it go to 1.0 instantly? If I leave it connected longer, it never drops any more.

My secondary windings reads 8.11K ohms.


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## InstantLegend (Jun 5, 2005)

No one knows the answer to this?

I found a manual on line for an 031 and it says the following for coil ranges
primary winding - 0.7 - 1.0 ohms
secondary winding - 7.7k - 10.3k ohms

Anyone know if this is the same for an 028WB?

Also, does anyone know how quickly the meter should get to the correct range (see my last post)?


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## Maytag (Dec 10, 2007)

A few tenths on the primary side reading shouldn't matter too much as you're mainly checking for an open wire. So real low, but above zero is good. Real hi (megohms) is bad. You're checking the resisitance of a relatively short thicker wire so it has low resistance. The reading is probably changing due to the 1 ohm "short circuit" that is being applied across the meter. The battery inside the meter applies a voltage to the wire and the meter reads the current through the circuit. This drains the battery down until it reaches a more stable voltage within a few seconds.

For the secondary side you're looking for shorted windings (really low ohms) or open (really hi ohms). This is where experience or a shop manual help. Your reading of 8k sounds about right. Without the shop manual you could have several windings in the coil shorted out and still have say 6K for a reading. Coil might still produce a spark, but it may not be strong enough to jump the plug gap correctly. Here your testing a fairly long thin wire prone to breaking or shorting out to its neighbor (the way its wrapped in the coil) due to the heat stress from the engine and high voltage breakdown of the insulation.

Hope this helps.
>Maytag - the loneliest cable guy in town :dude:


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## billsmowers (Mar 21, 2008)

You Realy Need To Test It Under Load Conditions With A Proper Coil Tester Like This One THIS WILL TEST POINTS COILS CDI, TCI COILS


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