Chevy and GMC Duramax Diesel Forum banner

Inj #4 no fire

2K views 10 replies 5 participants last post by  SilverGorillaLML 
#1 ·
Rough idle, code P1232, occasionally it will throw 0304. Checked balance rates, inj #4 shows 15 even, the others are all good to go. Checked the cabling at the alt bracket as I found online, all good there. Tested ohms across the connector on the drivers side for #2 & #4, both show .5ohms there so I think the injector or at least the solenoid is good. I'm guessing I have a grounding issue somewhere in the harness? This happened after the dealer replaced the FICM btw.
 
#2 ·
Its going to sound stupid but put some dielectric grease on the connections, it cures a lot of little gremlin issues. I think its a loose plug or ground somewhere along your line of thinking. These days we need a bell for our trucks just like motorcycles!
 
#4 · (Edited)
Ok, finally got time to really tear into it. Checked wire harness from injector back to c1 connector at the FICM. Check voltage while running, #2 and #4 both show 24v to ground so looks like the FICM is telling that injector to fire. Balance rate for that injector is 15. Any way to test injector without pulling it? I checked ohms across the injector, it matches the rest, .5ohms. bad injector??
 
#5 · (Edited)
OK, checked the control wires from the CM to the FICM. Key on, ENG off, #4 should be lt blue/black stripe. It has 5v as well as the other 7, so I'm getting control from the ECM, fired engine and checked, still had 5v on #4 but the other 7 bounced at 4.975ishv.
 
#7 ·
Much admiration for your persistence in getting your truck fixed. Few would go that far.

I wish I knew what to tell you but I don't. You have replaced the original #4 injector with #1 injector and now that original #1 injector has same characteristics as old #4. I'm assuming that when you say the balance shows 15, you mean +15?? (it is adding power to the revolution where -15 would be the opposite). You have check the electronics every way you can. I don't recall if you have replaced the injector connector itself, that's the only possibility I see there.

I wonder if there is something in the tuning causing this. Might be worth a call/message to the tuner if you can locate him to see if that is even possible, or if he may have any ideas what might be your problem.

Best of luck to you and be sure to post your fix when you get this figured out.
 
#9 ·
Much admiration for your persistence in getting your truck fixed. Few would go that far.

I wish I knew what to tell you but I don't. You have replaced the original #4 injector with #1 injector and now that original #1 injector has same characteristics as old #4. I'm assuming that when you say the balance shows 15, you mean +15?? (it is adding power to the revolution where -15 would be the opposite). You have check the electronics every way you can. I don't recall if you have replaced the injector connector itself, that's the only possibility I see there.

I wonder if there is something in the tuning causing this. Might be worth a call/message to the tuner if you can locate him to see if that is even possible, or if he may have any ideas what might be your problem.

Best of luck to you and be sure to post your fix when you get this figured out.
I sent ya a PM.
 
#8 ·
No running, stock ECM, swapped it out as well. Have swapped injectors and problems stays with that cylinder. Reading +15, so it's telling the injector to dump fuel right? Just not doing it? I's got to be this dam wiring.
 
#10 ·
Finally tracked this dam thing down after pulling the valve cover and swapping injector harnesses, that didn't work. Traced the lt. blue/black stripe cable from the FICM back to the ECM, the cable separated at the harness connector above the drivers valve cover. Test drive was great but now no oil pressure. plenty of oil. guessing sending unit shit the bed.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top