Cat C-9 Engine miss on pull

[Steve Humphrey]

Just spent 5 days in the shop for an engine miss under a load.  They changed the ECM and replaced a pressure switch, which did not solve the problem.  The answer turned out to be the oil pump in the injector pump that powers the injectors.  Inasmuch as we purchased it used and had no service records we do not know how often the oil was changed.  It is my opinion that the C-9 needs to have clean oil and that lowering the change interval to 7,500 miles or once a year will save money in the long run.

[Jim Nichols]

They didn't find a bad injector?  How much was the pump in the injector pump and labor?  Reason for asking is we also had a miss under load at low rpm. At 37, 000 miles had one injector replaced and it solved the problem but is showing up every so often at 85, 000. We change oil approximately 10, 000 to 12, 000.