Question about 2003 Mercury Grand Marquis

3 Answers

I started having a problem about a month ago. My 2003 Mercury Grand marquis LSE tuned up at 100k currently 145k. started hesitating and slight bucking at cruise speed. I went to autozone and coded #8 cyclinder misfiring replaced coil and spark plug. still had the same problem brought to a mechanic he ran the code replaced same coil and spark plug with OEM parts and still have the same problem, except it is getting worse. It is still intermittent at times but now happens at idle, cruise and upon acceleration. feels like it is about to stall. brought back to the mechanic car was acting fine so no codes and no help from friendly mechanic.

Posted by on

  • ralph481 Apr 01, 2011

    Is there anything I can try? since the mechanic checked for codes and found none. Would compression and vacuum not throw off a code of some kind? Is there any other ideas for a solution?

    Thank you

  • ralph481 Apr 01, 2011

    Just drove the car back to the mechanic while running rough this morning and the check engine light came on. The mechanic said cyclinder #5 misfire now what.

×

Ad

3 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 388 Answers

Check the number 8 plug wire to be sure it hasn't corroded or burnt through at some point. It wouldn't hurt to replace that wire with a new one. If yours is the 4.6 liter you also may have a bad fuel injector on that cylinder causing it to either burn lean or over fuel causing the misfire.

Posted on Apr 01, 2011

Ad
  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Master
  • 2,926 Answers

A misfire can be related to a number of causes. Since the coil and spark plug were replaced and it did not solve this issue, it is most likely related to the circuit for the number 8 cylinder. A thorough inspection of the electrical circuit is what is required next. Also, engine compression will need to be tested on that cylinder as well as cylinder number 6 that is next to it. Vacuum leak around the intake port of the number 8 cylinder could also be a cause and will need to be checked.

Posted on Apr 01, 2011

  • GetMeOttaHere Apr 01, 2011

    It is already throwing a code....misfire #8 cylinder.

×

Ad
  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Master
  • 2,427 Answers

Well from what your describing it sounds as if your car is stalling cause of 2 reasons,

1.) fuel pressure, have the mechanic check the fuel pump pressure (no sensors so it dont show up in diagnostic)

2.) check your air filter / throttle body, could be a problem with the air fuel mix ratio.

Posted on Apr 01, 2011

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of.(from cars to computers, handyman, and even drones)
click here to download the app (for users in the US for now) and get all the help you need.
Goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Where is the fuel level sensor located on a 2002 mercury marquis grand marquis


it is inside the tank attached to the fuel pump assembly that part is available seperatly but if you have 100k or more i would replace the whole assembly

May 10, 2014 | 2002 Mercury Grand Marquis

1 Answer

2003 Mercury Grand Marquis w/ less than 100k miles-lost reverse; all other gears fine.


Usually what causes this is your reverse clutch is worn out in the transmission, or there is a bad valve

Dec 19, 2011 | 2003 Mercury Grand Marquis

1 Answer

Tune up question


That depends on your definition of a tune up. You should clean an air filter annually or sooner if driving on dirt roads. At least by 30,000 mis. you should have a new air filter. New spark plugs should be put in by 60,000 to 100,000 miles depending on your driving conditions (length of trips, etc.). Also a fuel filter(s) should be on your list if you have not replaced it or them by this age. How many miles have you got on your car?

Feb 14, 2010 | 2003 Mercury Grand Marquis

1 Answer

Heater wont come on.


sounds like the vent flap is stuck

Jan 23, 2009 | 2003 Mercury Grand Marquis

2 Answers

Electric


yes i've checked the fuses :(,but they are all good...

Sep 21, 2008 | 2006 Mercury Grand Marquis

Not finding what you are looking for?
2003 Mercury Grand Marquis Logo

221 people viewed this question

Ask a Question

Usually answered in minutes!

Top Mercury Experts

yadayada
yadayada

Level 3 Expert

76846 Answers

fordexpert

Level 3 Expert

5546 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22246 Answers

Are you a Mercury Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...