12.7 Detroit DDEC 4

need a injector cut out test, take cyl. temps at manifold from cold start. Ecm will not see mechanical fault with a injector.

 

second the cylinder run test. maybe the cam lobes are damaged.

 

Look i fuel tanks for air bubbles

 

I agree with jamespmack, cut-out test, check temps as it's warming up, then pull the return line off and run in a bucket looking for bubbles (stab the throttle a few times to check if compression is getting in). That's exactly where I'd start. If that all checks out, double check valve adjustment. I have seen many injector harnesses rub through inside the convoluted tubing and cross fire without setting faults too.

 

grape your right about harness, I wasnt going there yet. If one is around a million and valve cover is off. I change it.

 

But never for get the first thing is to check grounds and battery connections. Ecm fuse holder. I have seen some weird stuff. Had one that as you increased heater blower motor it increased engine rpm on every setting. But when you hit the 4 ways it loped. Engine to block ground.

 

I’ve got a 2001 Freightliner with a 12.7. Replaced turbo, all new fuel lines and fittings, boost sensor, ran the overhead, tested all injectors, used temp gun to check cylinders to see if the heated up equally, checked for boost leaks, all new filters, and it still doesn’t have any power. Looking for any help I can get. The truck seems to do ok until you get to 10th gear then it will not pull anything.

 

If you have done all of that. I would now put it on a dyno.

 

I had it dynoed in December and it was putting 470 to the ground. I failed to mention that this is a recent problem. I have 34 psi of boost and my pyro will get up to 900 at times with an empty trailer and about 700 bobtail