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Old 01-24-2022, 08:25 AM   #1
vdubjunkie
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Member#: 260057
Join Date: Oct 2010
Vehicle:
2004 WRX Wagon
silver

Default Have you ever..?

Have any of you ever heard of an ECU killing spark to a single cylinder?



My son's 2013 WRX had a single cylinder go out. The problem did not follow the new coil pack, nor the new spark plug, stayed with the cylinder. Compression checked out, injector checked out. Coil pack removed from the cylinder and grounded proved no spark, when another cylinder, same method, did have spark.


Two of three coil pack wires common with other coil packs have continuity to other coil packs, and the third wire (to ECU) has continuity all the way back to the ECU. The third wire also measured the same (2.47V?) as the other coil packs. We had no means of measuring pulse width to ensure the voltage was, or was not dropping to collapse the magnetic field, but everything points to it not doing that.


So, we started down the rabbit trail of replacing the ECU, which hasn't gone well so far. We thought it a good time to step back and see if, ideally somebody who is employed to troubleshoot these engines at a dealership, can tell us that an ECU definitely would not do that.
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Old 01-26-2022, 03:45 AM   #2
Snocash
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Its pretty common for the clip to the coil packs to break off, Make sure its seated correctly and the rubber gasket on the inside isn't all mushed up. I would do the grounding test again and really make sure its in there all the way.
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Old 01-28-2022, 04:43 AM   #3
vdubjunkie
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The ground test is being done identically. The problem stays with the cylinder, not follow the coil pack.


Does anybody know whether an ECU would kill the spark to a single cylinder? I've got a master mechanic of many years stumped by this.
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Old 01-28-2022, 08:57 AM   #4
86Dreams
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'21 Giulia Q4

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Quote:
Originally Posted by vdubjunkie View Post
Have any of you ever heard of an ECU killing spark to a single cylinder?
I have never seen thisasked. If you cant find anything through the Nasioc search (not google) its fair to say its never happened. and I would take that as indicating that its highly likely that the answer to your question is No. You could try asking over on the rom raider forums as well.


Quote:
Originally Posted by vdubjunkie View Post
Two of three coil pack wires common with other coil packs have continuity to other coil packs, and the third wire (to ECU) has continuity all the way back to the ECU. The third wire also measured the same (2.47V?) as the other coil packs. We had no means of measuring pulse width to ensure the voltage was, or was not dropping to collapse the magnetic field, but everything points to it not doing that.
Did you resistance test the third wire? How does the resistance compare to the resistance of a wire for one of the good coil packs?


Quote:
Originally Posted by vdubjunkie View Post
So, we started down the rabbit trail of replacing the ECU, which hasn't gone well so far. We thought it a good time to step back and see if, ideally somebody who is employed to troubleshoot these engines at a dealership, can tell us that an ECU definitely would not do that.
Why has this not gone well?
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