I've noticed that in the 96 PSD I recently purchased that once in a while, I get 2 cylinders that miss. Other times it sounds like 4 cylinders are missing. It's got 330k on the clock. Exhaust is clear and it fires right up in 60 degree weather even with glow plug relay unplugged for testing.

What should I be looking for? I swapped in a spare IDM from another 7.3 I had previously and that didn't change anything.

 

Broken wire in the harness or loose UVCH connecter would be where I would look first.

Hopefully you oil level is ok. Low oil can allow air in and seem similar.

 

Check the valve cover pins, and harness for burned pins. Also check if the harness pigtails have ever been changed out, and if they have , that the wires are soldered together. Butt connectors are not a good option, as I tried them a few years ago, and got a misfire after a year or so use. after soldering the wires I had no more problems.

 

Thread update. I did two things and it's been better since:
1. There was a burnt pin but it was the glow plug not the injector
2. Overhauled injectors.

My guess is the 2nd was the issue, but having changed two things, I may never know.

 

The good thing is that it is fixed.

 

If a GP terminal is damaged, it can easily cause a short between itself and the adjacent injector. That can take out a whole bank. When you lose two or four, is it consistent WHICH two and WHICH four?