For Steven Petry. 2005 S-type sport 4.2 with 125,000 miles. I need to know what to do about a winter hot soak problem. This has happened routinely each winter for the last 3-years (starting at about 90,000 miles): We go down town shopping on a Saturday. Typically we make 4 or more stops in stores that have their own parking lots. Each stop takes about 20 to 30 minutes inside the store. Coming out of the 3rd store, the car will start but runs extremely rough. I have to give it gas to keep it going (anyone else would call a tow truck). By the time we get to the street, the cars is running fine, although the check engine light will come on by the time we get home. I check the codes and always get ÔÇ£random misfire, cylinders 1, 3, or 1, 3, 5, or 1, 3, 5, & 7. I erase the codes. First year I had the injectors cleaned, but the problem came back. I am convinced the hot soak problem (vapor lock in the injector) is caused by the winter fuel blend we get in the Willamette Valley of Oregon. I understand they add butane to this blend which is very volatile. Changing to unleaded (lower volatility) seems to help. The problem stops in March, when the spring fuel blend become available and comes back in late October. FYI, Last summer I got a bad coil code on cylinder 1 and replaced that coil. No similar codes since. Spark plugs replaced at 100,000. Fuel filter replaced around 90,000. IÔÇÖm erasing the codes about 3-times a month now. The cars runs fine otherwise and starts right up in the morning, but it hardly sees anything below 26 degrees. No one seems to have a solution, but all are willing to through expensive parts at it (coils), i.e., they donÔÇÖt have a clue! Car gets regular oil changes every 5,000 miles, but nothing else has been replaced. I always try to get close to 200,000 miles out of a car and still love this one.
