Hey guys, my old 2004 5.4 is missing on cylinder 5. If I’m correct, that’s the front one on the driver side. I’ve tried a new coil pack and plug and that didn’t help. My next move was to move the #4 coil pack connector to #5 and it worked. I’ve been using an inline spark tester to see what’s happening. I’m thinking I may have a bad ICM. I’ve checked all the coil pack connectors including #5 and all are getting constant 15 volts. You guys have any other ideas?

added information: 230k miles on the truck, sufficiently rusted. I’m unable to get codes, not sure why but that’s been the case for years.

 

Yes #5 is driver's side front, towards radiator.
Bad ECM/PCMs are a rarity
"My next move was to move the #4 coil pack connector to #5 and it worked. " Please add steps taken and what worked?

 

I unplugged the coil on #4 and placed the #4 connector on the #5 coil pack. That’s the only way I can get fire on that coil pack on #5.

 

that was not a good idea/plan.

Pcm supplies coil with a ground at the time needed for each cylinder (ie you swap parts/coils to test, you DONT mismatch the connectors).

Let’s back up, what (exact) code number have you gotten ?

 

Swapping connector from #4 to #5 seems like a stretch, literally. We need good accurate information to help you solve this problem
So as laterongc mentioned you should swap parts and check codes. COP = Coil-On-Plug
Verify you still have P0305
Identify COP #5 by marking it with a magic marker or piece of tape so that you can keep track of what went where
Remove COP from cylinder 5 and swap it with any other. Reset (erase) codes. Make sure the COP connector "snaps" into place. Run engine long enough to generate a P030x code.
If you still have a P0305 then pull the spark plug from #5 and swap it with any other. Run engine long enough to generate a P030x code.
Make sure the connector on #5 snaps into place. Also check the wiring (visual) to see if there is any damage.
If you still have a P0305 then pull the injector from #5 and swap it with any other. Careful fuel pressure will exists in the injectors. Run engine long enough to generate a P030x code.
You will likely find the problem using this method.
Report back with results

 

Here are a few possibilities to consider:

1. **Coil Pack and Connector Check**: Since you swapped the #4 coil connector to #5 and it fired, it suggests there could be an issue either with the #5 coil pack or its associated wiring. Make sure that the connector on #5 is securely connected and inspect the wiring for any visible damage or corrosion.

2. **Inspect the Spark Plug**: You might want to remove the spark plug on #5 and check its condition. If it's fouled or damaged, replacing it might resolve the issue. Conversely, you can swap it with a spark plug from another cylinder to see if the problem follows the plug.

3. **Fuel Injector Check**: As suggested, swapping the injector from #5 with one from another cylinder may help isolate the issue. Make sure to take necessary precautions as there will be fuel pressure in the system.

4. **Check for Codes**: Even though you've mentioned you have not been able to retrieve codes, it might be worth checking again after performing these tests. An OBD-II scanner can sometimes yield crucial information — even pending codes might give you an indication of what's malfunctioning.

5. **Consider the ICM**: If none of the above steps resolve the issue, the Ignition Control Module (ICM) could potentially be the cause. However, it would be more effective to rule out all other possibilities first.

6. **Wiring and ECM**: Since you're dealing with an older vehicle with high mileage, ensure that all electrical connections are clean and free of rust or corrosion. A bad connection can contribute to intermittent issues.

 

^^^ this, but would add/suggest that parts from 5 go to all different cylinders (and take notes). That way if you didn’t wait long enough for a code to pop, and it does later, you aren’t wondering (or misdiagnosing) which part actually caused the code. If using diff cylinders you eliminate that possibility.