Cummins n14 injector issue

Insite tends to smooth out the n14 when performing cut out test. I've been told something to do with the data link.

Try manually cutting out by unplugging pass through or checking manifold temp with a thermogenesis.

Absolutely check injector wiring. Check from ecm to pass thru on each inj. Inj 4 supply is pin 15 in actuator connector (back top ecm connector) return is pin 6.

These engines are very fickle about good 12v. Make sure batt terminals are clean and tight, i have fixed a few misfires on celect pluses like that before.

Make sure adjustment is correct. Of all else seems good I would inspect cam for wear or damage. Just a thought

 

Great advice! you would be testing the harness itself right? Making sure it’s got voltage and checking for resistance too with both plugs unplugged? I need to get better at checking for continuity. I got the basics down pretty good. I have done it on the field and at home on circuits that I can reach both ends on.

I know the engine position sensor and the main starter to frame ground cable have been two fixes of mine in the past for abnormal idle on my n-14.

 

Yes. Unplug ecm and pass thru, check resistance from ecm connector to pass thru pin, both supply and ground. You should also check it to other pins in connector and a good block ground to test for shorts. .2 to .3 or so will be ok depending on your meter. OL pin to pin. OL to block ground on supply side. You should have continuity on return side to ground.

Yes you can also check voltage when running. I have a small car headlight in a little Tupperware that I will use to load test, just unhook connectors and run your lightbulb on one end to your battery. Pretty accurate load test usually.

Last question: has this issue been present since changing cam followers?

 

With pass through unplugged the ecm should fault immediately for the corresponding cyl. I have seen instances where that does not happen and the inj driver in the ecm is not working correctly.

It may be becoming more pronounced because depending on the calibration, sometimes engaging the test will change idle speed. If you have a test ecm available that would be a wise move to try.

One more thing to check is the check valve to the ecm cooling plate. Should be right on the inlet from your suction line. Remember 4 is the last cyl in the order... more often than not that causes more havoc than this but I've seen stranger.

If you're sure all you're wiring is correct you need to move on to cyl 4 mechanicals. Check dumb stuff, did you bend a push tube when you pulled it out and moved inj, ect. Take oil fill cap off and check for huffing, can indicate cracked or hole in piston causing cyl imbalance. I would also check adjustment both valves and head. Good luck.