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Weird no spark problem.

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Old 05-21-17, 09:39 PM
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Weird no spark problem.

Some info on the car: S4 body S4 turbo II engine swap. Car started and ran before pulling the old engine.


Checked ENG INJ fuse. Pulled the plugs to check for spark and wasn't getting one. Tested resistances on the coils and C.A.S they seem good.


I then checked if there was power getting to the coils, there should be 12 volts when the key is in the ON position is what I saw in previous threads.


I got 0 volts when ON but with the ignition off and the key out I got 12.56. I assume this is backwards to what I want but have no clue where to go from here, any suggestions would be appreciated. Best guess would be something to do with the ignition switch? This seems weird considering it was working before.
Old 05-22-17, 02:18 PM
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Sorry, I had been awake too long yesterday since when I went out to check the main relay today and I rechecked the coil power plug again and got 12 volts like I should be according to some old HAILERS' threads.


When I was checking the leading coil primary terminal resistance I got 14.91 and read in a previous thread that 12.65 was acceptable but thought this might cause a weak spark instead of no spark since this is happening with the trailing coils too.


Going to look for a new or working used leading coil and see if that fixes the problem. Looks like s4 and s5 are interchangeable? If that doesn't work Maybe the ecu isn't sending a grounding signal and is bad is all I can think of. Any input is appreciated.
Old 05-23-17, 02:34 PM
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After searching for some old ignition problem threads I went out and checked the green wire from the leading coil connector and it shot up to 5 volts while hand cranking the engine then went back down like I hear it should.


Tried this with the trailing coil as well and noticed a spark so I'm pretty sure it has to be a bad leading coil.




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