Drivers of 2000-05 Lincoln LS or 2002-05 Ford Thunderbird models (all with 3.9-liter engines) may come up to your write-up desk with a complaint of a misfire and an illuminated check engine light.
Your scanner may reveal trouble codes P0301 through P0308 in the PCM. According to Ford, the condition is limited to vehicles built up to May 1, 2004, and is most likely due to water accumulating in one or more of the ignition coil wells.
The water gets in the wells through a deformity in the foam seal at the cowl panel. Removing the water, installing new ignition coil covers, Part No. XW4Z-12025-AD, and replacing the foam cowl seal with an updated design, Part No. 5W4Z-54021A46-A, should eliminate further misfire issues.
Start the fix by disconnecting the electrical connectors at all eight coils. Now remove the retaining bolts and twist the coil boots off the spark plugs. Inspect each boot, replacing if damaged.
Using a blow gun, thoroughly dry the coils and coil wells. Next, apply dielectric grease inside each coil boot, reinstall the coils and tighten the bolts. Install new ignition coil covers on each bank of the engine.
Now that the ignition system is dry, turn your attention to the foam seal at the cowl panel. Begin the replacement by removing the cowl panel grille. Using the illustration above as a reference, peel off the old foam seal from the cowl panel. Using a suitable solvent, clean the seal mounting surface on the panel.
Now install the new-design foam seal on the cowl panel, making sure it's centered over the drain tube, as shown. To complete the fix, reinstall the cowl panel grille and clear the misfire code(s) stored in PCM memory.
"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].