Weird Rough Idle Problem 2000 Grand Marquis - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
Ford Forum Ford Forum

» Auto Insurance
» Featured Product
ยป Wheel & Tire Center

Go Back   Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > Ford Cars and PAG Vehicles > Ford Crown Victoria | Mercury Marauder | Grand Marquis | P71
Register Home Forum Active Topics Photo Gallery Auto Loans Garage Mark Forums Read Auto Escrow

Ford Crown Victoria | Mercury Marauder | Grand Marquis | P71 Forum for discussion of the Ford Crown Victoria, Mercury Marauder, Mercury Grand Marquis and P71.

FordForums.com is the premier Ford Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 07-19-2006, 22:25   #1 (permalink)
Registered User
 
Join Date: Jul 2006
Posts: 2
Weird Rough Idle Problem 2000 Grand Marquis

My 2000 Grand Marquis has a rough idle. I am getting about 19-20 mpg highway, which is below average for this car. The car has 90k miles on it. I just replaced all the coils with no improvement. I then unplugged each coil one by one as it was running, and the idle dropped with each coil, so I know it is firing on all 8 cyls. I have no check engine light nor do I have any codes stored in the ECU. The rough idle is especially noticable with the car in gear. I have also tried new plugs, fuel filter, fuel injector cleaner in the tank. Does anyone have any ideas???

Thanks
jccog is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 07-20-2006, 19:45   #2 (permalink)
Registered User
 
Join Date: Dec 2003
Posts: 160
Re: Weird Rough Idle Problem 2000 Grand Marquis

I would check to see what you voltage is at the TPS sensor. Also I would think about cleaning you MAF sensor. And check and see if your IAC is working proply.
amo4387622 is offline   Reply With Quote
Old 07-21-2006, 06:48   #3 (permalink)
HO conversion guru
 
Join Date: Aug 2005
Location: Georgia
Posts: 83
Re: Weird Rough Idle Problem 2000 Grand Marquis

Agreed, clean or replace the MAF sensor. Ford has recently had a butt load of TSB's regarding dirty/faulty MAF sensors. the most common symptom is a rough or surging idle.

there is a new product on the market at the parts stores that is specifically for cleaning MAF sensors. DO NOT use carb cleaner as it leaves an oily film. Electrical contact cleaner is the next best alternative if you can't find specific MAF cleaner.

make sure you disconnect the negative battery cable to clear the PCM memory after you clean the sensor.
88grandmarq is offline   Reply With Quote
Old 08-05-2006, 10:37   #4 (permalink)
Registered User
 
Join Date: Jul 2006
Posts: 2
Re: Weird Rough Idle Problem 2000 Grand Marquis

I tried cleaning the MAF with napa electronic parts cleaner with no change. How do I check the IAC as someone suggested? I haven't checked the TPS voltage yet either? Can anyone tell me which wires to probe on it to check it? What about injectors? A buddy told me that someone else ended up having a dirty injector with a similar problem. Still getting 19 mpg after cleaning the MAF.

Thanks
jccog is offline   Reply With Quote
Old 08-05-2006, 20:14   #5 (permalink)
Hi-Tech Redneck
 
Johnny Mullet's Avatar
 
Join Date: Jun 2006
Location: Ashtabula, Ohio
Age: 44
Posts: 1,486
Re: Weird Rough Idle Problem 2000 Grand Marquis

PM me your VIN# or post it here. I will check for service bulletins.
Johnny Mullet is offline   Reply With Quote
Old 08-06-2006, 11:43   #6 (permalink)
Hi-Tech Redneck
 
Johnny Mullet's Avatar
 
Join Date: Jun 2006
Location: Ashtabula, Ohio
Age: 44
Posts: 1,486
Re: Weird Rough Idle Problem 2000 Grand Marquis

The only thing I found was an update for the PCM which can be reprogrammed at your Dealer for a charge.

You do have an open recall...................

05N04 - Some of the all-composite intake manifolds used on 4.6L SOHC engines may develop fatigue cracks at the coolant crossover duct which could result in external coolant leakage. Drivers may be alerted of this potential leakage by the coolant level and/or coolant temperature warning systems. The recall will only be performed if a coolant leak is detected at the intake manifold crossover.
Johnny Mullet is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > Ford Cars and PAG Vehicles > Ford Crown Victoria | Mercury Marauder | Grand Marquis | P71



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Powered by vBadvanced CMPS v3.2.2

All times are GMT -7. The time now is 23:39.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.6.0
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.