1999 Detroit 12.7 Misfiring.

Sounds like it's sucking air, or getting air in the system. Does it start up smoking?

 

Similar problems on mine too. Been chasing it, replacing fuel lines, just when I think it’s fixed, happens again. Often wondered about the air inlet temp sensor. I thought it was called the barometric pressure sensor. Now I’m even more confused. Lol. On that year Truck, often the fuel shut off valve located under the cab leak. It’s the type with a rod handle, marked left , both, right. They’re super expensive to replace. They quit using them due to leaking. Instead lines are plumbed together. No valve.

 

When you release brakes how much does the reserve tanks drop and does the compressor kick on at the time the misfiring starts? May be compressor related. I’ve heard many compressors on old engines kick on and make popping sounds thru the stack that sounds like a stuck valve or just makes the engine sound like it has a high lift cam. Compressor cuts back out and engine runs steady again.

 

I have seen the ambient air temp sensor cause some white smoke and a little sluggish ness. But no misfire. Usually when it’s ambient air causing a problem there is no code but you go in the data list and see the reading off considerably from the actual air temp. To confirm you unplug it and it normally straightens up

 

Ya, the compressor gets it's oil, coolant, and intake air from the engine so,...wouldn't take much of a compressor top end or component issue to affect the engine.

 

Does it only smoke worse when the engine is cold and you release the park brake or does it do that when the engine is hot too?

I believe there was a warm up option the Series 60 had where it'd run on 3 cylinders when cold until the engine either warmed up or the park brake was released, then all 6 kicked in. If those are your symptoms I'd be looking for something common to all 6 cylinders like fuel supply.

 

I have a hard time believing it has anything to do with the compressor. I'd forget what you think it has to do with it and diagnose the miss alone.

This is how you get off down a rabbit trail pissin time away.