2 coils not sparking

JoeyHemi

Member
May 7, 2019
4
1
13
19
Texas
Sooooo, my 1 and 4 coils aren’t firing and I have changed the spark plugs, the spark plug wires, the coils, and the PCM. What is their left???
 
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wmburns

SN Certified Technician
Aug 14, 2009
5,298
409
164
Houston Texas
Sooooo, my 1 and 4 coils aren’t firing and I have changed the spark plugs, the spark plug wires, the coils, and the PCM. What is their left???
Just wondering. What model year Mustang are we dealing with? 1996-1998 (coil pack) or 1999-2004 (COP)?

Since you stated "spark plug wires" I'm going to assume this is a coil pack ignition system.

Confirm HOW you are testing for spark. With an external spark tester?

Are you absolutely positive that the correct plug wiring has been used? The correct cylinder to coil pack tower? The coil pack ignition is affected by spark plug wiring routing.

What have you done to rule out a problem with the signal return lines to the PCM? Have you tested for opens or short to ground?

V8 coil pack diagram