Greetings from Arizona; I am hoping someone here would have some ideas on what might be going on with this car.
I have a 2003 Ford Crown Victoria P71, 4.6L, auto transmission. Over the last few months, it is becoming increasingly noticeable that when driving under certain conditions, the vehicle appears to either be mis- firing on a cylinder or the tranny is slipping - that is what the symptoms exhibit.
The conditions are that I am accelerating, but ONLY in the lower range of the gear, that is to say, when the vehicle is at a relatively low RPM. If I gas it even more so that a lower gear is engaged, the problem either "goes away" or is just masked by the higher RPM, I can't tell which. It is especially evident when going up a hill when, like I said, the RPM is not very high and it's in the lower range of the gear, or just when accelerating "slowly". It appears to happen in all gears. It's a stuttering or hesitation of sorts.
It's not throwing any codes, it idles perfectly, the motor does not appear to be missing at all when giving it gas in neutral or idling or when I tested it by applying the brake and gave it gas to see if I could simulate the problem. Otherwise this car drives and operates perfectly, save this one problem.
I find it hard to believe that the tranny is the culprit given the symptoms, but what do I know. Someone else suggested that is might be a certain ignition coil that when under "load" is mis-firing (the car has coil-on-boot ignition coils) but at $56 a pop, I'd rather not replace all 8 on a hunch. I have already replaced the spark plugs and serviced it for regular maintenance but still, the problem persists and I just can't figure it out.
Any suggestions or ideas would be greatly appreciated. Thanks,
-Ponga