Cylinder 1 Misfire

Two weeks ago I had a coil pack go out in cylinder 1. Replaced it and it ran great. A week later it began doing the same thing so computer read Cylinder 1 misfire again so I changed out plug and coil pack, but did not change anything. Truck does crank and run, but very rough. I am having a compression test done tomorrow. Just wondering what I’m looking at to fix this and if anyone has any solutions. Not very mechanical so take it easy on me. Any help would be appreciated.

 

So you’re on your 3rd coil pack? Did you use oem or denso? How did you diagnose first coil pack as bad?

 

Correct, OEM. saw cylinder misfire on computer and assumed it was coil pack. I changed one about 4 years ago so I knew the symptoms and just assumed it was another coil pack given the computer code.

 

Current coil pack and spark plug have fire, still getting cylinder misfire code with rough idle and lots of shaking while driving.

 

Well you are left with air, compression and fuel. I’m betting it is getting air since valve issues are rarely seen on these trucks.

Which basically leaves Fuel an Compression.

 

Check the junction block for the igf wire, the IGf signal confirms that ignition has actually occurred. In the event of a failure to trigger an ignition event, the ECU will shut down injector pulses to protect the catalyst from flooding with raw fuel. They signal from all is one common wire back that is shared for all the igniters, but they all come together at a common junction block.

 

The truck is currently at shop where compression test will be done tomorrow. I’ve been told by some people I’ve asked it could need a motor so I’m obviously hoping to avoid that (since my 07 only has 305k on it, it’s really just getting broke in ) please excuse my ignorance I’m just not good with something this in depth.

 

You should see a P0351 if the PCM wasn't seeing an IGF signal from the #1 coil, the PCM will disable the injector for the current drive cycle on any cylinder that sets a coil circuit code or if it sees too many consecutive misfires on a cylinder.