2001 Land Rover Disco 2 ... hesitation on acceleration

Discussion in 'Discovery' started by adicuss, Jul 6, 2019.

  1. adicuss

    adicuss New Member

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    2001 Land Rover Discovery 2 - gas V8
    Had an intake manifold leak on lower intake... fixed now.
    Caused numerous codes. 14 of them altogether.. It ended up making my car run lean and burnt out the cats.
    I ended up replacing both CAT's, MAF, coils, new plug wires, throttle position sensor, crank position sensor ,fuel pump, plugs.
    Now runs better with more power but seems to still be hesitating under acceleration.
    I replaced the CAT's first and everything after. I didn't find the intake leak till I replaced all these things.
    Possibly melting out the CAT's again because of it running too lean.
    I didn't replace the injectors though, they are original.
    Now from 14 codes to only two remaining and hesitating. I can feel the truck being held back when accelerating and not exactly full power.
    The only codes remaining on the OBD are #P0140 and #P0141.
    Any help on what you think it might be???
     
  2. joey

    joey Custom Rover Accessories Staff Member

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    You could still have a bad O2 sensor or the air filter box has not been closed properly letting in weirdly causing the MAF sensor to read wrong.
     
  3. Schoemann

    Schoemann New Member

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    Give a check for a vacuum leak under the vehicle. I have one between the back of the engine and the fuel tank somewhere. I get the hesitation and it is very bothersome. It makes the vehicle feel like I am towing something.
     
  4. BeemerNut

    BeemerNut Full Access Member

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    Joey, had to ask, how can the "air filter box not been closed properly" cause a problem when the mass airflow or hot wire sensor is reading air down stream of the air filter?
    There is a reason why the ducting from the air box to the air mass or hot wire sensor has a smooth bore and straight as possible allowing for smooth straight air flow vs turbulent tumbling air entering the meter for the most accurate air mass readings. Any air leaks after the mass or hot wire system well yes will cause all kinds of fuel ratio lean out problems. Air leaks be it at the air filter box or ducting BEFORE intake duct and mass or hot wire system has no effect or very little at best as the mass or hot wire sensor will send the proper signals to the ECM hence proper fuel ratio with normal running. Engine will run normally with air box cover and filter removed, around the block a quick road test never running normally on a long trip without a filter.
    In regards to "still having a bad O2 sensor", that's an easy and free check with O2 sensor's function finding out if all the O2's sensor's voltage outputs are scaling up and down. Any weak or dead O2 sensor will maintain a rather steady lower voltage output plus operate rather sluggishly. Upstream O2's voltage swings much wider range than the down stream O2's unless your lucky to own a OB1 95 and older vehicle with only two upstream O2 sensors.
    Checking O2's and locating a bad one if that's the problem is a lot cheaper than buying a set of four of them. O2 sensors if not been drowned by playing submarine, contaminated by antifreeze (blown head gasket), overuse of intake cleaning additives or an oil burning engine, O2 sensors will still function normally even at 250,000 miles. Any vacuum lines including smog related rubber plumbing hoses that have become brittle due to heat and age then failing will cause more damage like destroying old but still functioning good Cats and just as quickly destroying newly installed Cats. A quality digital meter is your wallet's best friend plus knowing how to use one properly will save you several hundreds if not thousands of dollars vs just throwing parts at it until it's finally running properly. A good scanner allowing you to read live on a screen able to switch from digital to analog dial readings running plus showing fault codes is well worth owning. Not a fan of several rather expensive scanner brands that only show fault code numbers. Better to be able to read sensors knowing their outputs are within normal operating output specs than just a sensor fail with a code number. A system able to read O2 voltage outputs if they are getting weak before replacing them allows you to keep track of their functions before they end up just dead.......~~=o&o>.......
     
    Last edited: Jul 13, 2019
  5. BeemerNut

    BeemerNut Full Access Member

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    This chart of OB2 fault coudes should help ya;https://www.freeautomechanic.com/diagnostictroublecodes6.html
    This should direct you to one O2 sensor and possibly why it is not getting power to the sensor's heating element unless the element has failed along with the sensor itself DOA.

    Has me thinking you might still be running in "limp mode" condition which will get you home under reduced power.
    Down stream O2 sensor items were added to all 96 and newer vehicles. Out of my interest zone OB2 vehicles owning a 95 D1 OB1 vehicle only requiring two upstream O2 sensors. No OB2 LR vehicles by choice......~~=o&o>......
     

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