Random misfire

Hi,

Are you presently getting codes P3401 and P3449? Those are the deactivation codes for cylinders 1 and 7. I need to know if that is the case. If it is, there is a wiring issue. It could be a short to power, open circuit, or a short to ground.

If you have a scan tool that can operate components, with the engine running, command the affected cylinder deactivation solenoid "on" and "off", with a scan tool, while observing the following cylinder deactivation control circuit status parameters. From that you will know if it is an electrical issue.

Let me know.
Joe

Can you give a little more detail about the cylinder shutting down as soon as you start the engine? Do you mean that you have misfires on 1 and 7 as soon as it starts? Does the engine run rough?

Just to make sure, did you install the active fuel management lifters in these cylinders? If not, this is most likely the issue.

Take a look at the attachment where it says 1, 4, 6, and 7 are your management cylinders and require different lifters.

Let's start with this and go from there. Thanks

Interesting. Are you sure that they both were installed with the notch correctly placed as shown below? If not, then it sounds like they are getting shut down like you are in 4 cylinder mode. That is the purpose of this system that it closes these valves by having the lifter stop moving the valve and it traps air in the cylinder so that when the piston comes up it compresses air which acts like a cushion. In other words it is an inactive cylinder but the air cushion helps bounce the piston back down.

The fact that the valves are not operating when the engine starts points to this as the issue.

If we are sure they are installed correctly then we need to look at the control side but that is unlikely as it is only 2 of the 4 cylinders which points to an issue at the cylinder like the lifter.