help cat gods

help cat mechanic,I have a 2009 c-15 550 in a westernstar has 63000 miles under a long pull it starts skipping like its runing out of fuel , it doesn't do it all the time,no check engine light,and on a same long pull when it's regenerating it pull's fine, we have taken it to cat did injector test, fuel pressure test, all ok, they say they can't do any more till it throws a light, any help,thanks.

 

The wires being untwisted shouldn't effect it. I thought you stated that you'd replaced the wiring harness between the ECM and valve cover spacer and the wiring harness under the valve covers for the injectors and jake brakes.

 

You're almost loose on the backlash. It's supposed to be .0085 with a plus or minus tolerance of .0045 The max is .013 and the least amount is .0040. This is very important to remember when doing backlash on the cam gear...........you always rotate the engine in the same direction as it would be when running...........pin it on number one........if you miss the pin...........neverreverse the engine rotation to insert the pin. This increases the backlash by allowing the lower gears to be come involved in your measurements. If you pin the engine properly.........you've taken the lower gears out of the measurement, because you have tension on them from rotating the engine and camshaft in the proper direction. As soon as you move backwards in engine rotation..............you've screwed up


The 0022-11 code will not cause the engine to missfire or drop power as you've discribed. When the engine dies suddenly under full power and your laptop is showing the fuel rate going to zero.........the fuel will not be dumped from the fuel galley into the return. When the ECM takes fuel away from the injector the fuel is dumped from the injector body into the fuel rail/galley in the head.........the fuel pressure is controlled by the check valve in the filter base. The ECM has no control over fuel pressure in the fuel rail/galley.........the reason you're seeing a quick spike in pressure is the ECM decided that fuel wasn't going to be fired by the injector into the cylinders........so no fuel volume is lost in the fuel galley and pressure goes up. Under full load the ECM is telling the injectors to use fuel so pressure goes down under a full load...........take the load away and the engine is still at higher RPM .......the fuel pump is still moving a large volume of fuel and the pressure rises until the pressure drops below the check valves closing point. The fuel delivery and return on these engines is completely mechanical.