Originally Posted by justa03
New to the forums but this one has got me stumped. Truck is an 03 with SCT Performance tune and muffler and cat delete. Noticed about 2 days ago at an idle the truck was running slightly rough. Took it out and drove it and under WOT the truck has no power and smokes black big time. Took it into work, hooked up the IDS and found that cyl 4 is dropping at idle and trucks acting like the turbo is stuck. Picked up a new injector grabbed some tools and went to my shop and installed a new cyl 4 inj and removed the turbo and cleaned which it really needed. Got it all back together and drove back to work to drop my tools off and found that its still dropping at idle and has no power. Hooked the IDS back up and found cyl 4 is still dropping at idle. Ran KOER self test and found cyl 4 contribution. Ok possiblely bad inj from Ford from the factory, wouldnt be the first one I seen. Ran relative compression and all cyls are equal at 0. After running the relative compression truck is a crank no start. Ok checked ICP and is low from 320-410 psi. Maybe cut the D ring on the inj? Well let it set for about an hour and truck restarted so I figured I cut the D ring, took it home for the night didnt have time to dig back into it.
Next day take it in and cyl 4 is still dropping, removed inj and found no cuts in the d ring, no obvious signs of damage to HP rail. Had another guy crank it over and found no oil leaks on that rail visible to the eye after 30 secs of cranking. Found that one of the o rings on the line from the stand pipe to the HP rail was slightly messed up, didnt have one at the dealership so just put it back in to get the truck out, installed another new inj into cyl 4 and test drove it again and still the exact same concern. Anyone with any ideas? Im kinda stumped, thinking maybe possibly a FICM issue but theres no codes for it, voltage was 48-47.5 while cranking. Cabs getting lifted for studs and egr delete in 2 weeks so I figured I could pressure test the HP oil system then when the ICP is easy to get to unless someone knows of an easier way? Thanks in advance and there is alot of good info on this Forum!!!
Before id whip an expensive ficm in, if it were my truck id first say screw the relative compression test. Ive had that give false readings BIG TIME. Especially when diagnosing a 6.4. Id do a manual compression test or shove a borescope down and inspect it. Before id even do that! Id pull the oil fill cap at idle and verify whether it is or isnt a base engine concern. if it puffs like a choo choo train out of the oil fill tube on the right hand valve cover you know theres blow by... Then id go in with the manual compression test and the Borescope.
Have you tried wiggling the injector harness while in power balance mode? How about in power balance mode do the injector interrupter and not cancel 4 but watch whether or not 4 drops. Remember with the interrupter on, it brings all 8 injectors to a pre-determined level of fuel and timing to help further diag an engine performance issue. They should not deviate not 1 bit. If cyl 4 drops -10 -20 -40 -60 then you know its the injector not firing or a base engine concern.
As for your HPO leak id fix that while i was in there.
Get an assistant have them monitor the power balance test and you go in and wiggle the harness while the engines running. make sure they look for any further deviation or whether cyl 4 comes back up. then either repair the harness or replace it.