Ignition coil replacement

Gotta love that wiring . . .
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Buffspartan
Posts: 4
Joined: Mon Mar 27, 2017 7:17 pm
Your car is a: 84 pininfarina

Ignition coil replacement

Post by Buffspartan »

Can a Blue Bosch coil be used in an electronic ignition system? I have an 84 Fiat spyder 2000. My original coil is getting voltage to the primary but no spark from the secondary circuit.
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Ignition coil replacement

Post by 18Fiatsandcounting »

Buffspartan wrote:Can a Blue Bosch coil be used in an electronic ignition system?
I don't believe so. The Fiat electronic ignition coil should have a primary resistance of around 0.8 ohms, and the Bosch blue coil is around 3 ohms (which is suitable for points ignition).

But, are you sure the coil is the problem? Other possibilities are a bad Ignition Control Module (ICM) or the pickup coil inside the distributor has failed (usually it's the wires that go bad). Both of these are common problems.

-Bryan
Buffspartan
Posts: 4
Joined: Mon Mar 27, 2017 7:17 pm
Your car is a: 84 pininfarina

Re: Ignition coil replacement

Post by Buffspartan »

Wouldn’t the coil still produce spark even if the pickup coil in the distributor was bad? Where is the ICU located? Is it behind the coil?
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Ignition coil replacement

Post by 18Fiatsandcounting »

Buffspartan wrote:Wouldn’t the coil still produce spark even if the pickup coil in the distributor was bad?
No, it won't. If the pickup coil is bad, there is no trigger to tell the ICM to fire the coil.
Buffspartan wrote:Where is the ICU located? Is it behind the coil?
Yes, the ICM usually is located behind the coil, mounted directly to the heat sink. It's a black box sort of thing, about 1/4" thick and 3" long, with two spade lugs on one end (W and G) and two on the other end (B and C). W and G go to the pickup coil wire, B goes to the + side of the coil, and C goes to the negative side of the coil. Plus there is a 5th connection which is one of the mounting screws to ground the ICM.

-Bryan
Buffspartan
Posts: 4
Joined: Mon Mar 27, 2017 7:17 pm
Your car is a: 84 pininfarina

Re: Ignition coil replacement

Post by Buffspartan »

You were correct about the pickup coil. Once I replaced it I get spark. Thanks!
However, I cannot keep it running. It’s acting like the timing is off. Is my gap off on the pickup coil( .023)? Or does timing really change once the pickup coil is replaced? I did not remove any spark plug wires off the cap. Any help is greatly appreciated.
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Ignition coil replacement

Post by 18Fiatsandcounting »

Did you remove the distributor to change the pickup coil? If so, your ignition timing almost certainly changed.

Also, opinions vary on this, but I tend to favor a little bit less gap between the pickup coil and the little vanes beneath the rotor. Perhaps 0.4 to 0.50 mm, which would be around 0.020".

-Bryan
Buffspartan
Posts: 4
Joined: Mon Mar 27, 2017 7:17 pm
Your car is a: 84 pininfarina

Re: Ignition coil replacement

Post by Buffspartan »

Distributor was not removed. Problem solved however. Turns out magnet on pickup coil was upside down. No markings on it so I was unaware this was the problem. I reversed magnet and re- gapped at .022. Fired up and runs perfectly! Thanks for all your help!!!!
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