Some 2005-06 F-Super Duty pickup trucks with 6.0-liter diesel engines may buck or jerk in the 1800-2500 rpm range under a steady throttle or slight throttle tip-in. According to Ford, the problem is most noticeable when the engine is under a load and usually occurs when the transmission is in first or second gear. Though the condition occurs more frequently on trucks with manual transmissions, it can also occur on pickups with automatics.
Software gremlins in the PCM are the most likely source of the trouble. Reprogramming the module with updated calibration files is the only reliable fix. Check with a Ford dealer for the specifics on the update.
Owners of 2002-03 Altimas and Sentras may come into your store with a complaint of a rough idle. They may also say that the engine bucks while driving or that it's down on power when accelerating. Once you get in the car, you may find that the check engine light is on with trouble code P0102 and/or P1102 stored in PCM memory.
According to Nissan, all these symptoms could be the result of dust and fine road debris entering the air filter housing and contaminating the mass airflow meter. Cleaning out the housing with compressed air and replacing the airflow meter and air filter should eliminate the drivability concerns.
Chrysler reports that some 2007 Jeep Wranglers built prior to April 4, 2007, may produce an oily leak under the front of the vehicle. Once you get the truck on a lift the source of the leak will become pretty obvious—a prematurely worn steering damper seal. What causes the seal wear are chips, nicks or abrasion on the damper rod. The rod gets damaged by stones, gravel, pebbles, etc. being flung from the road surface upward. Replacing the steering damper with a new unit will take care of the leak. But to prevent a recurrence, change the mounting position of the rod end of the damper from the axle bracket to the tie rod, where it's less likely to be subjected to road debris.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected]