Hello all! I'm working on a 09 LMM ambulance. It came in with a under power complaint. The injectors have been done previous to this and with the same complaint. Today I test drove it up a fairly steep grade under full load, as soon as the fan came on full it seemed to begin misfiring then seemed to drop a cylinder or cylinders bellowing smoke and knocking horribly. I let off to about half throttle and after a second or two things went back to what sounded like normal so I kept on my way watching scan tool and waiting for the problem to occur again. Once I was out of traffic I went back to 100% throttle and once again it began to miss and bellow smoke along with knock only this time I let it go a bit longer at that time I noticed a ball of fire out the exhaust and let out of the throttle until the fire was out, pulled over and checked rig over. All seemed ok so I once again went on my way back to the shop. The rig ran ok (still under powered and a slight miss) I arrived back at the shop and removed the dog house and noticed #7 injector was leaking at the copper injector to head seal now I'm thinking this isn't the only problem being that the rig came in for this problem before injectors where replaced. I'll add all balance rates seem in check others then # 7 balance on power and injector was around 525. Fuel psi is reaching desired 26000 and only drops once the knocking starts also I checked the fuel suction side and never went past 8" under load and 2" at idle. I do notice when I take off the oil fill cap theres pressure vapor that seems to be consistent with the slight miss at idle. Any help would be great thanks in advance.
