Misfire made worse

[JeepGirl1013]

I bought a fuel pump from dead jeep a while back and after a few months I needed to prime the pump to get her to start. Figured the regulator was going out. Dropped the tank and replaced the regulator only. Also changed spark plugs they were showing discoloration on one side and had some bluing. Figured maybe lean air fuel mixture due to the pump issues. Fuel injectors were clean and looked great. Now that the tank’s back on, I’m getting a flashing CEL and P0306 & P0301. I bought a new coil rail but didn’t install it because it seemed to be getting power just fine. Now I’m wondering if I need to put in the new coil rail or if there’s something else I could be overlooking? Checked the lines to the gas tank and they are good. Any thoughts?

 

[CharlesHS]

I spent a couple years trouble shooting the Random Misfire codes and specific cylinder misfires.
Tried the Mopar CCC and Seafoam in the gas tank and in the throttlebody several times, replaced spark plugs a couple times, inspected the igniter rail boots/clips and finally replaced the rail, replaced the CMPS, and installed new fuel injectors, but the problem returned.
While replacing the clutch assembly the flywheel triggering blocks were observed to have a build up of rust particles on the surface and the CPS also had debris on the sensing end.
Replaced the flywheel during clutch repair and cleaned the CPS sensing surface; the problem has been gone ever since.
IF you have exhausted all troubleshooting as I did; try removing the CPS to inspect the sensing surface and while this may be tedious; inspect the flywheel triggering block surfaces for rust.

 

[Moglocker]

I bought a fuel pump from dead jeep a while back and after a few months I needed to prime the pump to get her to start. Figured the regulator was going out. Dropped the tank and replaced the regulator only. Also changed spark plugs they were showing discoloration on one side and had some bluing. Figured maybe lean air fuel mixture due to the pump issues. Fuel injectors were clean and looked great. Now that the tank’s back on, I’m getting a flashing CEL and P0306 & P0301. I bought a new coil rail but didn’t install it because it seemed to be getting power just fine. Now I’m wondering if I need to put in the new coil rail or if there’s something else I could be overlooking? Checked the lines to the gas tank and they are good. Any thoughts?

Put the old plugs back in,if it was running good before the pump? I wouldn’t change too many things at once,sometimes that will get you problems that are hard to solve.what brand of plugs?did you get the coil seated on all the plugs?

 

[JeepGirl1013]

Put the old plugs back in,go if it was running good before the pump?

It wasn’t running good before. Now we don’t have to prime the pump but the misfire is worse.

 

[Chris]

I spent a couple years trouble shooting the Random Misfire codes and specific cylinder misfires.
Tried the Mopar CCC and Seafoam in the gas tank and in the throttlebody several times, replaced spark plugs a couple times, inspected the igniter rail boots/clips and finally replaced the rail, replaced the CMPS, and installed new fuel injectors, but the problem returned.
While replacing the clutch assembly the flywheel triggering blocks were observed to have a build up of rust particles on the surface and the CPS also had debris on the sensing end.
Replaced the flywheel during clutch repair and cleaned the CPS sensing surface; the problem has been gone ever since.
IF you have exhausted all troubleshooting as I did; try removing the CPS to inspect the sensing surface and while this may be tedious; inspect the flywheel triggering block surfaces for rust.

Great advice!

 

[B1Toad]

Since you had to disturb the coil rail to change the plugs I'd suspect that. Maybe some crossfiring going on?