Ignition coil testing (I've read the FAQ)
 

I'm testing my ignition coils, well atleast I'm trying to.

In the FAQ the terminals are labeled 1-3. On the coils themselves they're labeled IB, ground, and positive. I've tried testing the 10 coils that I have in front of me, and atleast one of these is known to be bad. However, I'm getting similar resistance readings for all of them.

If possible, I'd appreciate it if somebody could walk me through coil testing. Maybe I'm doing something wrong.

Thanks.

I think that the positive terminal is the number one terminal. Put the positive lead on your ohmmeter on the positive terminal and the negative lead on the negative terminal, you should get infinite resistance. Reverse the leads and you should get something like .16 megohms. Then check between where the sparkplug goes and the positive terminal to check for a short between the primary and secondary coils, again you should get an infinite reading. Just because it tests good with this method doesn't mean that it isn't on it's way out. It could still be bad or going bad. I think that this is correct, somebody let me know if this is wrong.

Do you have a misfire? If so, turn the car on, unplug one by one, and see how the engine is affected... then you'll find your bad apple(s).

I had the same problem testing OHMs on pins 1, 2 & 3 everywhich way that you could, all within spec until I tested between where the sparkplug goes and the positive terminal to check for a short between the primary and secondary coils. All coils measured infinity except one that fluctuated between a reading of resistence and infinity depending on how the probe was positioned.

I have done that, but I need at least 3 of them unplugged till the car starts choking.

man... do it like a real man... the best way to test for a bad coil is in 2 ways....

run the car with all plugged in... then take one off at a time... if it causes MORE knock and changes the way the engine runs it means its good... if i does absolutely nothing... ITS BAD...

The other way is to get an ignition tester and test it that way.. a resistance value will only tell you if its totaly bad...not if its having problems... aka an intermittened problem....

I've got a nasty misfire, and I just replaced the coils less than a year ago.

I've tried disconnecting the coils one by one, but there really wasn't a big change in the idle. Not noticeable enough for me to detect a misfire. What method does the dealer use for testing coils? The determined that only one of mine was bad before, and replaced it, but that was under warranty.

I hate our coils. Why are they so $^&#*(% expensive? Where can I find Mitsubishis?

Bewtween 67-70$ each.

www.pinnaclenissan.com

Test the resistance of the coil pack with the car off. Use a multimeter on the lowest range for OHM. The positive should go to the left pin and negative to the middle pin. You should get a resistance of 1.0 or less. If not they are bad and you need to replace them.

then u need more than one

Checking resistance with a multimeter is done at low voltage. Your coils can test out fine but that doesn't mean the insulation won't break down at 30-50 kV and elevated temperature during actual operation.

What methods do the dealers use for testing coils?

Call and ask ...

They just check resistance.