Greetings,

We have a 1998 Ford E350 7.3 Diesel Cutaway with a Airport Shuttle Bus Coach Body. It weighs in at about 10K lbs.

We have noticed that under load conditions in 3rd and 4th (4R100) gear and even slight pressure on the accelerator, a vibration begins and continues until you let off of of it. It only happens in the lower part of the gear and as the vehicle speeds up, it disappears. Running flat on the highway at 75 is very smooth indicating that the shaft is straight and balanced as well as the wheels.

I just replaced the transmission (unrelated event) and the U-Joints. I also mounted a video camera under the chassis to see if there was anything obvious going on with the rear end/etc. Nothing appears to be loose/etc (mounts) and the axle isn't doing weird things either when vibrating.

From what I can tell reading lots of blogs/etc, many people point to a bad injector. Does the car computer report so-called bad injectors and would that be enough to light the engine light? How does a bad injector cause vibration when under load only?

I've sought out all the low hanging fruit with this problem without success, so far. I need a little pep rally to get me going again to solve this issue.

I am grateful to anybody in advance for your help!!

Regards,
Nuke