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I have a intermitent misfire with backfiring that I have been working on for a while now. I was reading my haynes manual last night and I checked the resistance between the the primary hot and ground on the coil and came up with 500 ohms and the books says it needs to be within 800 to 1.5 mega ohms. I know that its out of spec but its still pretty close. What do you guy's think?
Its a bone stock 5.0 with all emissions in place just like it was in the donor. I was disconnecting the batt after every time I ran it until I learned that it has to relearn. But I don't think that thats true because I was looking in the same manual and it said that that only applied to cars with distributorless ignition systems. It only does it when its cold. At least that is the way it seems, since I can not drive it far it's hard for me to be for sure.
 

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On the battery issue, it does apply to you too. The computer must have a 12 volt constant supply to "remember" it's adaptive settings.

From what I can find online right now, I believe the reading between the coil's primary terminals (the + and - terminals on the coil) should be more like 0.3 to 1.0 ohms.

Make sure you are reading it right. Use the "x1" scale of your meter to read basic ohms.

There are a couple of coil checking tips here:

http://www.autozone.com/az/cds/en_us/0900823d/80/04/ce/c6/0900823d8004cec6/repairInfoPages.htm

Steve
 

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Found this on another site:

check primary resistance between Pos and Neg terminals on the coil
resistance should be 0.3 - 1.0 ohms

check secondary resistance between Pos term and coil wire terminal
resistance should be 8000 - 11500 ohms

repeat secondary resistance test between Neg terminal and coil wire terminal
resistance should be 8000 - 11500 ohms

check resistance to each terminal and gound(coil case)
resistance should be infinite

Steve
 
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