Archived 1998.5 Cummins 100hp Injector Issues

[Waydin Stewart]

I bought some DFI 7x.009 sac injectors and new cummins connector tubes. Install went smooth or so I thought. Truck took about 2 minutes in total to start while bleeding lines and everything. It ran had rough idle because of air. Then it went away but a small rough idle stayed. I can feel the truck shaking and can hear it in the exhaust at idle. Then at 1000-1200 RPM the truck shakes more and the miss is louder. I can drive it and during accelration you can hear the miss very prominent in the exhaust. The truck does seem to run better but I do not trust driving it under the current circumstances. I loosened all the injectors lines at the head and the idle changed pitch and fuel spit out on all 6 injectors. I took the valve cover off and re-torqued the hold down and made sure they were all torqued correctly. The truck is still doing it so I know it has to be a problem with the injector itself or a connector tube if that's even possible. I checked all the old injectors and they all have copper washers

 

[rkressg]

Sounds like a dead injector. Dumb question, but do you have good fuel pressure at the VP44? Do you have any codes? Depending on the age/wear on the VP44, it might have partly died.
It could also just be air stuck in the system. Did it ever smooth out?

 

[Waydin Stewart]

I have a brand new Airdog II and brand new VP44. Less than 1000 miles now but is going up everyday. So I know it has good fuel pressure and the pump is strong. I decided after driving it for a while I would drop some bigger sticks in it. So I bought the DFI 7x.009 injectors stated above and also bought Genuine Cummins Injector tubes, Because I had read that on a 1998.5 dodge if you buy bigger injectors the tubes are not long enough to make a solid connection. I checked and it was true my original connector tubes were slightly shorter. I contacted Chris and he sent another set out the next day. So I installed them and the rough idle is gone. I still have the odd exhaust sound now. If I just slowly accelerate you can just slightly hear the sound but when I really give it the juice the exhaust sound is very loud. It is coming from exhaust tip not the motor. I cannot hear it coming from the motor while driving. On hard acceleration the truck does wobble but that could be due to wore out u-joints and non-balanced wheels as the weights decided to go away sometime. It makes the truck sound like a non-turbo 7.3. It didn't sound like this before. Not even close so it confuses me. I was going to adjust the valves and see if that helped as they probably need to be adjusted anyways with almost 225,000 miles now. I just want to know why the exhaust still makes the sound. Other trucks my year model or newer do not make this sound.