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Amedee
Amedee, Mercury Technician
Category: Mercury
Satisfied Customers: 24390
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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Have a 1998 Grand Marquis GS. Have replaced the ign coil packs,

Customer Question

Have a 1998 Grand Marquis GS. Have replaced the ign coil packs, spark plugs, wires, f/p assy Have had scanner analysis/fuel pressure test perform pressurized fuel system service/clean carbon from throttle and mass air meter remove upstream O2 sensors to measure exhaust back pressure. Injector cleaner and used Cata/clean. Still have same problem. When idling and accelerating, the engine seems to shutter. At one time, I was traveling at 70 miles an hour. The engine throttled back to 60, 50, 40 then 30. I could mash the gas peddle to the floor and the car would not pick up speed. Pulled off the expressway. Reeved up the engine until you could feel it pick up speed. Pulled out into the traffic and the car was fine. When this happen, a mechanic did the checks above. Said that the problem didn't occur while in park. Said something about the fuel sensor. But changed nothing. The problem has started again. I have no idea where to go from here. Felt like trash in the fuel. Have changed the fuel filter twice. What do I do next?
Submitted: 7 months ago.
Category: Mercury
Expert:  Amedee replied 7 months ago.
Hello and welcome! Was the mass airflow sensor replaced? If not the sensor might just be bad. The mass airflow sensor is the number one input to the computer for injector pulse width. Is a very important sensor used to calculate air fuel ratio and the sensor goes bad all the time.
Expert:  Amedee replied 7 months ago.
If the sensor was just cleaned it may not be enough. The sensor may have to be replaced.
Expert:  Amedee replied 7 months ago.
Also don't forget the check for air and vacuum leaks under the hood. If the air intake snorkel from the mass airflow sensor to the throttlebody is cracked or ripped in anyway it will cause a severe lean condition.
Expert:  Amedee replied 7 months ago.
Hello! It'sCustomerfrom just answer. I am just checking in to see if you need any further assistance? Let me know!
Expert:  Amedee replied 7 months ago.
Hello! It'sCustomerfrom just answer. I am just checking in to see if you need any further assistance? Let me know!
Customer: replied 7 months ago.
On Friday, purchased the MAF sensor and had installed on my car. Still having the same problem. Since the check engine light has not come on, we can't diagnose the car.
Expert:  Amedee replied 7 months ago.
Hello! And all tune up parts check out ok? Fuel pressure is within specs? How about the oxygen sensors? Were they checked/replaced? What is the exhaust back pressure reading at when the engine is at 2000 rpm?
Customer: replied 7 months ago.
My mechanics will handle it from here. Please do not charge me $26.00. I just wanted you to know where I stand. Thank you for your past help.
Expert:  Amedee replied 7 months ago.
Your welcome

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