Mechanics

ENGINE STUMBLES AT 40 TO 50 MPH

2000 Mercury Marquis

Engine Performance problem
2000 Mercury Marquis V8 Two Wheel Drive Automatic 155000 miles

When I am driving along and accelerate at most any speed, but especially aroung 40 to 50 miles per hour my engine misfires and stumbles along badly. Once it reaches higher speeds and in on cruise control it seems to run correctly.

It throws a code saying the problem is with the EGR, but it has been thoroughly cleaned from the air cleaner to the plentum. Has a new EGR valve and solenoid.

Can you please give me some ideas?

Thanks

John
Avatar
Joshlin1932
September 18, 2010.



Lack of acceleration, chugging, hesitating, jerking, bogging, misfiring etc. Could be caused by one of the following below: Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard it.

Rasmataz
Sep 19, 2010.