I own a 2006 Mercury Marquis. Sometimes upon starting (without pressing on the gas) it starts with the engine racing extremely high which triggers the engine maintenance malfunction light. If I turn off the key and restart it will usually start fine. Also once in a while while driving down the road it will just start running really rough, once again triggering the engine malfunction light. Restarting it seems to solve the problem. Other than that it runs great.
sounds like system ground and/or a throttle position sensor....first assure that your battery is newer than five years old then with a coarse wirebrush, undo the 1/0 negative cable connection to the frame/ground...wirebrush the lug and the surface that connects the ground...install with your NEW battery~
What codes are in the computer? Your 2006 is a "fly-by- wire" design: there's no throttle cable connecting your pedal to the Throttle body - it's entirely computer controlled. Usually, you can get a parts store to check the codes for free but....codes are only indicators. They rarely point exactly to a failed component. See what codes you get and let us know. I work on a Fleet of 1997 to 2012 Crown Victorias (about 800 of them) - they're the same car with different badges. BTW, with the fly-by-wire system, there are 2 redundant systems and sensors that monitor the actual Throttle position. There isn't just one sensor to swap out - and it's expensive if you do it just because some guy on the internet said to. AND - you should never, ever need to touch the accelerator pedal to start a modern car, the computer does everything except twist the key (and some cars do that for you too!)
Has anyone ever had a problem with the transmission shifting out of overdrive at 55 mph with little to no throttle movement? It happened to me yesterday in a downpour of rain, resulting in loss of control and head on collision with another vehicle. Just curious if there is an issue with the "fly by wire" system in these vehicles?
WTF? Shifted out of overdrive into what gear? The fly-by-wire system has a redundancy built into it and defaults to near idle if ANY malfunction occurs. Please describe the failure/accident in more detail - it doesn't sound quite right. Did it shift into a lower gear and you had worn tires?
Looking for a Used Grand Marquis in your area?
CarGurus has 2,203 nationwide Grand Marquis listings starting at $1,995.
Search Mercury Grand Marquis Questions
Mercury Grand Marquis Experts