2008 MP8 hard to start. in Engine and Transmission Posted February 13 I have run into this twice recently and both times it was a bad injector. One is sticking open I believe therefore leaking down quickly. Both of the trucks I did, both ran great no drivability issues and no air bubbles indicating cups. There were no injector codes . Cylinder balance test will show it being off some but not really enough to condemn it on that alone.