2003 Excursion - Vibration (lengthy)
Lead Driver
Joined: Jul 2013
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From: In the field...
Injectors 1-7 on a late-model 7.3 are AD and #8 is an AE or "long lead." #8 sits at the end of the rail and fires immediately after the #6 cylinder goes boom. This means #8 gets shorted on fuel pressure and causes it to get an irregular rap at lower speeds, aka idle cackle. Ford addressed the issue by using an AE injector that has a longer primary shot of fuel to compensate for the lack of fuel caused by it firing immediately after #6. When running a CCT the #8 cylinder doesn't match the contribution of the other 7 so it shows as failing.
Tuned
Joined: Dec 2013
Posts: 458
Likes: 2
From: The Northwoods, Wisconsin
Injectors 1-7 on a late-model 7.3 are AD and #8 is an AE or "long lead." #8 sits at the end of the rail and fires immediately after the #6 cylinder goes boom. This means #8 gets shorted on fuel pressure and causes it to get an irregular rap at lower speeds, aka idle cackle. Ford addressed the issue by using an AE injector that has a longer primary shot of fuel to compensate for the lack of fuel caused by it firing immediately after #6. When running a CCT the #8 cylinder doesn't match the contribution of the other 7 so it shows as failing.
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mecDac - you mean just in general (per the "long lead" discussion) or for my issue?
The2003 - thanks for the input. I've run buzz tests and CCT's and all pass as they should besides #8 which is expected by design. Unfortunately the vibration seems directly related to the speed of the driveline and has nothing to do with the speed of the motor (vibrates when braking, with torque converter locked or unlocked, transmission in neutral or in gear, independent of RPM) or the load the motor is seeing (coasting, cruising, accelerating). It's definitely worse with a trailer hooked up (vibrates at lower speeds and also more intensely both driving and braking) so I originally suspected wheel bearings but I replaced them (Timken units up front, Timken bearings/races out back) and still had the issue. Then I was thinking a bad hub, however unlikely, or a wiped spindle but I get the same vibration with the new-to-me axle...
I really don't mean to come across as unappreciative (if I am) as I really do value any input. Just trying to delineate thought process regarding stated possibilities.
The2003 - thanks for the input. I've run buzz tests and CCT's and all pass as they should besides #8 which is expected by design. Unfortunately the vibration seems directly related to the speed of the driveline and has nothing to do with the speed of the motor (vibrates when braking, with torque converter locked or unlocked, transmission in neutral or in gear, independent of RPM) or the load the motor is seeing (coasting, cruising, accelerating). It's definitely worse with a trailer hooked up (vibrates at lower speeds and also more intensely both driving and braking) so I originally suspected wheel bearings but I replaced them (Timken units up front, Timken bearings/races out back) and still had the issue. Then I was thinking a bad hub, however unlikely, or a wiped spindle but I get the same vibration with the new-to-me axle...
I really don't mean to come across as unappreciative (if I am) as I really do value any input. Just trying to delineate thought process regarding stated possibilities.
Lead Driver
Joined: Jul 2013
Posts: 9,266
Likes: 150
From: In the field...
mecDac - you mean just in general (per the "long lead" discussion) or for my issue?
The2003 - thanks for the input. I've run buzz tests and CCT's and all pass as they should besides #8 which is expected by design. Unfortunately the vibration seems directly related to the speed of the driveline and has nothing to do with the speed of the motor (vibrates when braking, with torque converter locked or unlocked, transmission in neutral or in gear, independent of RPM) or the load the motor is seeing (coasting, cruising, accelerating). It's definitely worse with a trailer hooked up (vibrates at lower speeds and also more intensely both driving and braking) so I originally suspected wheel bearings but I replaced them (Timken units up front, Timken bearings/races out back) and still had the issue. Then I was thinking a bad hub, however unlikely, or a wiped spindle but I get the same vibration with the new-to-me axle...
I really don't mean to come across as unappreciative (if I am) as I really do value any input. Just trying to delineate thought process regarding stated possibilities.
The2003 - thanks for the input. I've run buzz tests and CCT's and all pass as they should besides #8 which is expected by design. Unfortunately the vibration seems directly related to the speed of the driveline and has nothing to do with the speed of the motor (vibrates when braking, with torque converter locked or unlocked, transmission in neutral or in gear, independent of RPM) or the load the motor is seeing (coasting, cruising, accelerating). It's definitely worse with a trailer hooked up (vibrates at lower speeds and also more intensely both driving and braking) so I originally suspected wheel bearings but I replaced them (Timken units up front, Timken bearings/races out back) and still had the issue. Then I was thinking a bad hub, however unlikely, or a wiped spindle but I get the same vibration with the new-to-me axle...
I really don't mean to come across as unappreciative (if I am) as I really do value any input. Just trying to delineate thought process regarding stated possibilities.
Posting Guru
Joined: May 2012
Posts: 1,758
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From: Colorado
Interesting. Did you have any codes or misfires before you decided to do this?
Tuned
Joined: Dec 2013
Posts: 458
Likes: 2
From: The Northwoods, Wisconsin
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As far as being engine related I guess it could be but with passing buzz and CCT tests I'm a bit hesitant to throw new injectors in - at 150k miles its arguable that they should be replaced anyways... But at $275 each its an expensive endeavour to undertake with no definitive signs...
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Thanks for chiming in HiZ. Unfortunately I've rotated and also swapped on two other sets of wheels and tires to no avail...
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