I checked my the Ohms on my stock coil on my D16a6 and hooking it up on the primary i got the reading of 0.07-0.08 Ohms, which is within factory specs according to my Helms manual...so my primary readings are good. BUT I checked the SECONDARY and all i get is an OL (overload) on my ohm meter. According to Helms the secondary should be between 9.7 and 14.6 ohms.

Note: My ohm meter has 2 settings on ohms, 200 and 200K ohms max.

Now why is the secondary overloading? Bad coil?

I am checking my coil because i suspect it being bad because of a possible weak spark(runs rich) and bouncy RPM on tach while driving, although the car runs great.

 

OL on a OHM meter usually means there is an Open Loop.

in other words there is a break in the connections (inside?) somewhere.......it could be a bad coil?

 

If you're using your ohm-meter correctly, an open circuit absolutely HAS to be a bad coil. Trouble is, that means the engine shouldn't be able to run at all. Not a weak spark, that'll give you NO spark at all. Since it runs, I bet there's something wrong with the resistance measurement.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RedRacerCivic &raquo;</TD></TR><TR><TD CLASS="quote">. BUT I checked the SECONDARY and all i get is an OL (overload) on my ohm meter. According to Helms the secondary should be between 9.7 and 14.6 ohms.

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I think the spec is 9700-14600 ohms. Try checking it on the higher range. And remember, even if the coil checks good, it doesn't mean it is.

 

If you had your meter on the highest selectable ohm range, and you were still getting "OL" on the meter, I'd say your coil secondary has become open.

But the secondary spec is in the 'K' ohm range...as Chiovnidca stated.

And also noted by Chiovnidca - just because the coil ohms out to spec, does not mean its good....I've seen a few cases here on HT that ended like this.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">

just because the coil ohms out to spec, does not mean its good....I've seen a few cases here on HT that ended like this.
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I've seen a few myself, wasted alot of time on them, that's why I don't even bother to check them anymore. I just hook up one of my test coils to be sure it's the problem.

 

Found out the reason why it was showing OL, the inside of the secondary was kinda corroded and i wasnt getting good metal to metal contact. I ended up getting a 12.6 ohms on the secondary, so my coil is good. I just wasted 100 bucks at Honda buying a new one! dammit

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RedRacerCivic &raquo;</TD></TR><TR><TD CLASS="quote">... so my coil is good. I just wasted 100 bucks at Honda buying a new one! dammit </TD></TR></TABLE>You could look at that a couple different ways. Once that starts corroding, it just keeps corroding faster & faster all the time. You're gonna have to keep taking it out & cleaning it again & again till you're sick of it. Maybe now it's an emergency spare...

'Course, now you're always gonna remember that when you're making a resistance measurement, you want to put your meter probes on a clean shiny metal surface. Metal oxides hardly ever conduct electricity.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">
Metal oxides hardly ever conduct electricity.
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They don't do they?

 

Agree with Chris and Chiovnidca. Here is a little background on why coils are bad that test good with an ohm meter. Its all about internal dielectric breakdown. Basically you trashed the internal insulation... but the breakdown is secondary voltage dependent.

Here is the usual scenario, your wires start to go bad, or a bad rotor or cap... or some corroded connections. The secondary starts going higher than the usual 20Kv ish breakdown... or you are boosting 20 psi and pushing 30+Kv breakdown. This high voltage stresses, physically, the insulation on the internal wire. It starts to get thin, stressed, unhappy and starts to carburize. Hence you get what is essentially a highvoltage zener diode... for you electronic types... Everything is A OK up to 30 kv... then with more age and abuse it is only good to 25 kv... you see the pattern. The missing gets worse and worse... yet the coil will test good with an ohmmeter that only puts 5 to 9 volts onto the coil...

Run it on a megger to check insulation breakdown and you will get a different answer... usually.

I too just replace coils now with know good ones. I've also seen too many test just fine, but breakdown at voltage.

Hope this helps explain the phenomena a bit ...

 

Usually when a tach starts jumping its the ICM(ignitor). The ICM should be on a mount with 2 screws on the outside of the distributor itself. Take those 2 screws out and the ignitor should just fall out. Then you can take it off the bracket.