Anonymous
Anonymous asked in Cars & TransportationMaintenance & Repairs · 1 month ago

Engine blowing smoke intermittently?

My Mercury Grand Marquis 2005 blows bluish smoke but not all the time. First time I noticed it was when car was in automobile shop for wheels alignment and when the guy was done aligning and was getting the car out of shop for a test drive, I saw smoke coming from exhaust and when he accelerated it increased and when he returned there was no smoke at all. Now yesterday when car was idling outside my friend's shop and we were having a chat, I saw engine blowing smoke slightly so I quickly went inside and revved the engine to see if smoke increases but it did not smoke at all on revving. Engine is not losing oil or coolant at all and it doesn't even overheat and car runs absolutely smooth without any hesitation.

Codes stored were P0135 (O2 sensor), P0401 (Exhaust EGR flow insufficient) and P0191 (Fuel rail pressure sensor circuit range performance).Then I reset the codes and checked again few days later and this time codes were P0135 (again), P0401 (again) and P0193 (Fuel rail pressure sensor circuit high).What could be the possible reason of it?

7 Answers

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  • Anonymous
    1 month ago

    How many MILES on the odometer? 

    Believe me, your engine IS burning OIL! 

    Make sure your PCV valve isn't clogged. 

    There are several problems that make an engine BURN oil.  Sitting at idle doesn't mean much. 

    Drive it hard and watch.

  • 1 month ago

    Leaky valve seals - - they cause smoke and clog the EGR and O2 with excess carbon in the exhaust

  • Anonymous
    1 month ago

    Valve seals are bad coupled with a bad O2 sensor, a dirty EGR valve and a bad fuel rail pressure sensor.  But I am just guessing.  You need to see a mechanic to confirm.

  • Anonymous
    1 month ago

    Lots of miles on your Merc?  Those are the typical symptoms of bad valve seals or worn valve guides . . . . associated with very high mileage or an engine that has overheated at some point ("frying" the valve seals).  Years ago it was common and we simply switched to a heavier grade oil.  A little bit won't hurt - a lot will foul the plugs.  The cure is to have the valve seals replaced, which can be done without removing the heads and isn't ruinously expensive.  Redoing the valve guides involved pulling the heads and is somewhat expensive.

    I recently had the seals replaced on a 1957 Studebaker - - everyone said the engine was worn (piston rings etc) but a Stude specialist suggested that the seales were hardened after 63 years, replaced them and that was the end of any smoking since and she's good as gold . . . . about $250.

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  • 1 month ago

    Now, you see that erasing codes doesn't fix worn out parts. Look up the codes and study the diagnoses and suggested remedies. Lookit: https://www.obd-codes.com/trouble_codes/

  • Anonymous
    1 month ago

    Without getting into the codes, blue smoke on startup may mean that the valve seals are leaking.  When that happens, after you shut it down, oil up on top of the head leaks down past the valve seals & drips into the combustion chamber(s).  It may not be leaking bad enough, yet, that you have to add oil. As far as replacing those seals, it's not crazy bad, it can be done without taking the heads off, BUT, nothing you have done at a shop is cheap.  If you don't plan on keeping the car forever, I wouldn't get too excited about it.

  • 1 month ago

    Blue smoke is an indication the engine is burking oil.  Probably it is bypassing the piston rings.

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