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misfire or O2 sensor?

Discussion in 'Ford Crown Victoria' started by bradleyheathhays, Nov 10, 2018.

  1. bradleyheathhays

    bradleyheathhays Member

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    Have an '11 Crown Vic with 280k that's been used as a delivery vehicle most of it's life. Just got it so I'm not too familiar with it's history.


    Two days ago I noticed at idle the engine had a variable missing / jerk shaking pattern, but otherwise drove fine. Next day the driving is much rougher. It seems to miss somewhat going through the first 3 gears but it's manageable with varying gas pedal. It's not until you get into O/D that things really start to shake. Soon as it switches up the whole car goes into a rumble. You either have to let off the gas or press harder, as acceleration seems to calm it down some. Engine light is permanently on and flashes when the rumbling is at it's worst. Wish I had some codes to quote but haven't had a chance to get it hooked up yet. Mechanic who I gave a ride to yesterday said it felt like a bad oxygen sensor. I asked if it could be an injector and he said the missing would be more consistent if it was.


    I'll be getting it read asap but in the meantime thought I would get yalls thoughts on it. What else could it possibly be other than an O2 sensor?
  2. Action

    Action Moderator Staff Member Respected Member

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    O2 sensors should be replaced every 100,000 miles. In it's life it is coming up on it's 3rd set if replaced as needed. The answer to your last question could be spark plugs and highly likely lack of maintenance. Let me guess - you bought it for cheap and it was not running all that well?

    Since the vehicle is new to you with a lot of miles and you do not know the maintenance history, I would be starting the maintenance clock from zero with all new.
    Replace air, oil, transmission & fuel filters. Crankcase filter if equipped.
    Replace fluids engine oil, transmission and coolant, brake fluid too
    Replace all spark plugs, all o2 sensors, serpentine belt and PCV if possible

    Clear codes and then drive and report back.

    >>>>>>>>>>>>Action
  3. bradleyheathhays

    bradleyheathhays Member

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    Thanks for that checklist Action. If I'd had more time this summer most of all that would've already been done. Overall I think the car was maintained to a somewhat reasonable degree. I know it was looked at by mechanics regularly as a fleet car. I've ran it about 10k city miles since getting it in May and this is the first major thing to happen. Out of that list so far I've replaced the oil and oil filter, fuel filter, coolant and 7 plugs, one won't come out.

    Wish I had remembered this earlier but about a week before this started I ran the best part of a can of seafoam in through the break booster intake, let it soak and put on the old smoke show. This one was particularly impressive. I've heard doing this can trigger a code for a bad O2 sensor, but that you just clear the code and go on. Wonder if that much smoke turned out to be the last straw for one of the sensors and it just failed?

    Did I see somewhere how you can clean one of these sensors with a blow torch?
  4. Action

    Action Moderator Staff Member Respected Member

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    You can get a replacements for less than $25 each. I would not bother cleaning them. Cleaning will not replace the metal lost. Same for that last spark plug.

    >>>>>>>>>>>>Action
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