I have a 2000 Grand Marquise 4.6. It runs well when cold, once warmed up it runs rough.
I had changed the plugs hoping this would solve the problem, it did not, though the plugs were in sad shape. The only error code I am receiving is a misfire in #2 cylinder. I listened to the injector it sounds consistent with the others. Should my next step be to replace the coil pack over that one spark plug? I've never experienced a coil acting this way. I realize some things are a process of elimination, but I don't want to just throw parts into it.
P0302 MERCURY - Cylinder 2 Misfire Detected.... Possible causes - Faulty spark plug 2 - Clogged or faulty fuel injector 2 - Faulty ignition coil 2 - Fuel injector 2 harness is open or shorted - Fuel injector 2 circuit poor electrical connection - Ignition coil 2 harness is open or shorted - Ignition coil 2 circuit poor electrical connection - Insufficient cylinder 2 compression - Incorrect fuel pressure - Intake air leak
Thank you for your insights. I will press in this direction. You have been a big help. Thanks again
So, In my situation, I replace the coil for the #2 cylinder. I cleared the code, took it for a test drive and drove with the live data stream hooked up so I could make sure the engine has reached it normal temp range. It ran great....smooth all the way around. Thanks again Rowefast.
You should have replaced all coils with Motorcraft coils. You likely will have problems again as this is a common issue with these cars. Using aftermarket coils is a hit or miss proposition. Sometimes they work and sometimes they don't last very long.
Your most welcome puzzled2...
Thank you Bob, I agree with your comment about replacing all the coils. I don't like doing things over. We have had a lot of repairs the last couple of months and our car funds were depleted. I did buy a Motorcraft coil though. Thanks again for your thoughts.
Good, Motorcraft although expensive is the best part for this application. Best of luck with it.
Looking for a Used Grand Marquis in your area?
CarGurus has 1,710 nationwide Grand Marquis listings starting at $800.
Search Mercury Grand Marquis Questions
Mercury Grand Marquis Experts