Ok, my boss and I have an 03 Expedition w/ 104K in the shop with the 5.4. Came in with a cylinder 1 misfire code. We changed all the plugs (they were the originals) and replaced the #1 ign. coil. Misfire is still present, but no codes. All injectors check out good. All coils check out good. Compression is from 170-185 on all 8 cylinders. Engine oil is 4k old, and was 2.5 qts. low. Coolant looks like its burnt, probably never been changed. In park, when idling, motor shakes lightly, vibration gets worse up to 2000 rpm, after that, feels fine, revs up to limiter nice and smoothly. When driven, motor chugs, no power, violent shaking. Vehicle also emits a very strong sulfur-like odor when running. Scanner real-time data shows ign. timing at constant 33 degrees advanced, O2 sensors on bank 1 and 2 are widely variable, 10-60 %, fuel trim is also all over the map.

We are beating our heads against the wall. Just can't figure this one out. Any help is greatly appreciated.

 

Sulfur smell means that there is unburnt fuel going through the exhaust. That would point to an ignition related misfire. Kind of a weird issue though. You might have to think out of the box on this one. I don't know how Fords are wired, but Audis are very sensitive to issues with the coolant sensor. A problem with that caused a variety of issues, from running rich all the way to a no start condition. BTW, you say no codes, but have all of the monitors run yet? Sometimes it takes a while to get all of them to run..

 

yeah, we spent all night on this. nothing points to a particular single issue. Personally, i think the motor is fried. everything was being monitored via scan tool w/ real-time. all systems showed a go. IMreadiness test also comes up clean. i considered ecu program gone bad. when any injector harness was pulled off, engine smoothed out. unplug any coil harness, engine smoothed out. im goingnuts over this. good news, if the motor IS fried, i might get the wholw truck for the cost of the bill, so i can use the motor in MY stang, and part out the truck.

 

you got a short. Betting that one of the coil signal wires is grounded or crosstalking with an injector wire. That it trims out better when you pull either of those off shows that the problem is there or related.

Tell them the motor is fried and use it in your stang.

 

Thanx to you both for offering advice and support. look to the 5.4 swap thread for the outcome.