12.7 Detroit missing

Most of the older Detroit do this I call it the Detroit stumble sometimes you revive it up and problems go away sometimes not Pittsburgh power thinks it's ecm related and they can fix it or gust get used to it best of luck

 

I have a 98 pete 379 with a 12.7 Detroit in it, been having this problem for months now. the problem is intermittent some days its great some days it acts up, right as you start rolling in the the throttle at lower speed and low rpm "1500 to 1600" it will start to pop and stumble and blow whiter grey smoke out the stacks it smells of raw fuel. does not do it at high way speeds. so far i have replaced the suction lines, filter head, new filter, new fuel pump, new map sensor, check check valve on return line and 0.80 restricted 90 on return. currently pulled all injectors out and re oringing them and putting new cups in, injectors have about 50,000 on them along with the entire motor, any help would be appreciated.

 

I realize this is an old thread, but since you have posted this in three places, I would like to throw this out there. It’s been a bunch of years since I worked in the Ftl/Detroit shops, however around late nineties and early 2k, there was a rash of intermittent misses on the 60 series that caused a lot of grief account of they were hardly ever acting up time they got to a shop. Eventually it was found that an injector terminal on the injector harness under the valve cover had become slightly “uncrimped”. This would cause the sensation that you and others have described. Sometimes, but rarely more than one terminal was at fault. It was found by using Pro-Link at the time time to see which hole had recorded “intermittent “ misses, or pulse width irregularities. The valve cover would be removed and pull test performed on suspect wire, and repair it. We fixed MANY of these and before we learned of this, it caused much frustration.
I realize Detroit did not have approved procedure for repair, account of resistance difference on that harness section being compromised, and the fact that the wires had silicone under the insulation which rendered it not conducive to soldering or traditional repair. But ya gotta do what ya gotta do to get him goin! They eventually worked that issue out and later models rarely had those issues that I’m aware.

 

@MAMservices Thank you for the reply, if it were to be the injector terminal connections would that throw any sort of check engine light? Because currently when the issue happens i have no check engine light fuel pressure holds the same.

 

It will not illuminate a light if happens quickly. A fault must occur for a certain length of time to set a code to turn on the MIL. 3 or 4 seconds if i remember correctly. If you check this and you can move the wire any at all in the terminal it is bad connection and subject to problems. Many times all that is required is to use a set of small crimping pliers and crimp the terminal tight again.

 

OK i will try to inspect and try to see if any of those wires are loose on there connections, iI really appreciate your feed back. Thank you
@MAMservices

 

Also look at the Ambient air temp or Intake air temp, it’s been several years and I can’t remember for sure which term they use. I found several that the temp would be way off, read 0 degrees in 80 degrees weather for instance and cause a stumble with smoke. Or a smoke after cold start. Doesn’t set a code, you can see it in the data list though.

 

So I've only been able to find the air intake temp sensor, sits right next to the MAP sensor in the intake manifold. I replaced that sensor thinking it may be bad but no change. I have yet to be able to find the ambient air temp sensor, I didn't know if they had them on these older trucks.

 

No you found the one I was referring too. Like I said it’s been 10 or 12 years since I fooled with one and couldn’t remember the proper terminology