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A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Mercury
Satisfied Customers: 6597
Experience:  ASE Master Certified. ASE Gasoline Engine Performance Certified,Ford Senior Master Technician
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Won't stay running, dies at stop lights if you don't put it

Customer Question

won't stay running, dies at stop lights if you don't put it in park. Idle is up and down. Check engine light is on solid and I am trying to find the port to get the engine trouble codes.
JA: Does the light stay on, or does it blink?
Customer: it stays on all the time
JA: What is the model/year of your Mercury?
Customer: 1995 Grand Marquis LS 4.6
JA: Are you fixing your Grand Marquis yourself? What have you tried so far?
Customer: I am trying to fix it for a disabled friend. I am looking for the connection to get the trouble codes to flash.
JA: Anything else you want the mechanic to know before I connect you?
Customer: nope
Submitted: 7 months ago.
Category: Mercury
Expert:  A. Penland replied 7 months ago.

The connection you are looking for is called the DLC (Data Link Connector). Ford tucked it up under the dash on the drivers side almost near the center above the gas pedal. You will have to look up under the dash near the center from the drivers side to see it. Below is what it looks like.

Customer: replied 7 months ago.
How do you get check engine light to flash the trouble codes? What is the procedure?
Expert:  A. Penland replied 7 months ago.

The best way is to stop by any auto parts store and have them connect their code reader up to get the codes. They will do this for free. Getting flash out codes on EEC V is not possible.

Customer: replied 7 months ago.
OK I didn't realize that this was an OBD2 car. I had read that anything prior to 1996 was OBD1, but I guess this is one of those exceptions. The codes are P0174, P1131, P1151, P0171, odte. Looks like these are codes pertaining to an engine running too lean and overdrive tranny. What is the most common things that could cause these codes & what things would you start fixing or looking for to clear these codes from first to last? The car does not get driven a whole lot and it's got about 89K miles on it. Thank you
Customer: replied 7 months ago.
It's idle will go up and down like the computer is trying to keep it from dying. It will die when you stop at a stop light unless you put it in neutral. The trans seems to be slipping on hills and rough shifts. I'm wondering if it dies at stoplights because of the torque converter.
Expert:  A. Penland replied 7 months ago.

Look at the lean codes P0171/P0174. The codes P1131/P1151 are results of the engine running lean, most likely caused by a vacuum leak or a faulty Mass Air Flow Sensor. Check the vacuum lines on the engine and the PCV hoses. Especially the hose that goes to the back of the intake manifold.