2003 Crown Vic hesitation........

I bought my first Crown Vic, and while driving it at highway speeds, I feel a stumble or hesitation at various speeds. I am new to these cars, so I am not familiar with the known or common issues. It feels like it is misfiring. I have no check engine light, and the autozone scanner showed no fault codes. Is this a common problem? Are the coils notorious for going bad? It is very random, and sometimes does not happen at all. But most of the time it does unless I really lay into the throttle. I have not changed the plugs yet, but it was a county car before I bought it, and fully maintained. It is a 2003 with 159000 on the clock. I have always loved these cars, and want to get this fixed.

Have you considered inspectrion of the fuel filter or replacement...?

Same for the air filter....just the general things....as you mentioned the spark plugs

Oil/filters....checked the tranny fluid/filter as well.

And as you mentioned ...it could be an electrical ....something grounding...or loose connection
somewhere...!!!

I have checked the air filter, and the oil filter was changed right before I bought the car (as it had an oil change by a local shop). I thought about the trans filter, but my work schedule has kept me so busy that I have had no time. I have read that the coils or plug boots can be an issue.

Stumble or hesitation can be caused by air filter, fuel filter, spark plugs, coils, or vacuum leaks. Now that you have ruled out the air and fuel filters, start looking for a minor vacuum leak before dealing with the coils / spark plugs.

One of the most OVERLOOKED problems with these cars, a vacuum leak can really cause havoc to an engine by causing a lean condition. You will need to use a non-flammable spray to try to pin point where the leak is and replace that line.

Another problem is the little wire set that goes from the COP to the spark plug. Moisture will get into these and start corrosion to break the contact. At about $40 from Autozone for a set of 8, you might as well change these if you change the spark plugs. And don't forget to add a little antiseize to the plug threads. There is a video on YouTube about removing these types of plugs to prevent from messing up the threads. Look and learn.

Also, you may want to bookmark www.RockAuto.com for parts. Even with shipping, most parts are cheaper than local shops. May I suggest looking at www.crownvic.net as a source of information on the CV/GM/TC vehicles.

I really appreciate all the info. I will start narrowing it down today. Lots to do, and I can't wait to get this car running right. It is a base model, and BONE STOCK!!!!! As soon as I work out the bugs, then I can start modding it.....

"jdmeaux"....you are the "source" of details....wow...

Thanks for your sharing, experience and knowledge....

I wished that I should have contacted you about my simple
headlamp switch removal/replacement...

I just figured I could figure it out....I did ...just a little longer than expceted

I'll post that experience and photos later on a different thread/topic

Thanks again "jdmeaux"

Do you have any records as to when the plugs were changed last?...The Motorcraft platium plugs only last about 80-85K miles. If the plugs have been changed, I would suspect a bad COP. With no mis fire code to tell you what cyclinder is mis fireing; you kind of have to guess. I would buy 1 new Motorcraft COP and swap it into each position. Good Luck