I think my coil died. Discuss...

[Chris Kouba]

Last I drove it about 2 weeks ago, I noticed a little bit of backfire which I (probably wrongly) attributed to air in the EFI high pressure loop. Tonight I took it out for a little spin and needed a tow home.

Car started and idled normally out of the shop. My run begins with a downhill leg of about a mile. There is a stop sign after 1/4 mi, and I negotiated this without issue. Car was running normally, or so I thought, but it was idling downhill to get there. It pulled away fine from the stop but I wasn't hard on it either as it was still not warmed up yet.

The next 1/2+ mile was downhill to another stop sign. I got up to speed casually from the stop and coasted the entire way down the hill to the next one. When I dumped the clutch to start braking and rowing gears, there was no motivation from the motor. I rolled across the intx and tried cranking it on the other side... No dice.

Got it home, confirmed no spark. I do have voltage to the coil. How do I test it? It's an Edelbrock Pro-Flo (first gen) with an MSD dist and coil.

Any other suggestions?

Thanks in advance!

Chris

 

[Phil]

Chris, I think you already tested it, if it has voltage and no spark its probably bad.
My experience with coils is that the majority are either working or bad, not much in-between.
Coils are basically a transformer with a very large voltage boost, so the secondary loop is by nature very thin wire...once they go its usually not fixable due to the construction.
Try hooking up another coil, even a non performance one to see if it fires...thats the cheap way to check it.
Good Luck
Phil

 

[Chris Kouba]

Thanks Phil, and it is confirmed. Replaced coil and it's as snappy as ever!

When I checked the new coil's resistance over the primary, I got 0 Ohms which I assume is bad. I hooked it up anyway. It didn't melt down the coil and since it was stable, I tried the starter... Magic!

It is supposed to have around .8 Ohm on the primary and 8k on the secondary. It's working for me now though so I'll see how long the OE one lasts.

Chris

 

[Phil]

Chris:
Thats good news, I don't know if it applies with your setup but some coils need a resistor to drop the voltage slightly, and with that setup there is a bypass while cranking on the solenoid to eliminate the resistor.
Glad you solved the problem and are able to use the car.
Cheers
Phil