Clueless

[Kevinhurley21]

I have a 2005 2500Hd. Truck sat for almost two months. When I started it at first it started to misfire and knock but then after a minute or two it cleared up. Let the truck run for a little while and it idled fine. Shut the truck off and came back 15 min later and now it runs but has completely lost one or more cylinders but never threw any codes at all. Any help would be appreciated! Thanks:)
2005 2500Hd Silverado
110k miles

[DmaxMaverick]

Welcome aboard!

Check for rodent presence (damaged insulation, turds under the hood, etc.), other environmental damage or corrosion. 2004/2005 also had issues with the injector harness chafing. Check for DTCs (trouble codes).

[Kevinhurley21]

I had the wiring issue about a week after I bought it and already repaired that.

[DmaxMaverick]

Is the SES lamp on? Does it stay on once running? Do you have a code reader / scanner? I would start with that. At the least, you should have codes for the misfire, and which cylinder(s) affected.

[rapidoxidationman]

#2 and/or #7 injector socket likely needs an ice pick treatment or replacement.

[Kennedy]

Sitting with free micrordroplets of water (untreated fuel) can wreak havoc on the fuel system. The LLY fuel system is about the most reliable of any so long as it is treated properly.

I do second the wiring thing. Not just the injector connectors, but over by the FICM, and also near the ECM can rub on the inner fender liner.