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Thread: D2 V8 running too lean, MAF sensor?

  1. 30th April 2011, 05:41 PM #1
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    D2 V8 running too lean, MAF sensor?

    Hi All,

    My Disco 2 has started to randomly chime on start up, two or three times per week. Have cleared the fault codes and the two that are returning are:

    Fault 35 (P0174) and 27 (P0171). Basically left and right bank are reporting "Fuelling adaption additive Bank1/Bank2 maximum value exceeded. Present and Intermittent."

    The MAF sensor looks like it is working OK at idle and responds to throttle changes. Never the less I have ordered a new one to try.

    It looks like these MAF sensors have a habit of failing, mine is 258,000kms old.

    Is there anything else that I should be looking at? I'm thinking blocked or dirty injectors or low fuel pressure at the injectors may also cause this fault. A couple of cylinders are indicating rough running on the live data. I'm not sure how this is detected and if I should do anything about it. I've been using the Hawkeye for all diagnostic and error reporting.

    Will post up my results once the new MAF has arrived.

    Cheers
    Ron
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  2. 30th April 2011, 05:56 PM #2
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    Really, really common with Thor D2 engines Ron, what are your MAF outputs in Kg/hr at Idle?

    JC
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  3. 30th April 2011, 06:15 PM #3
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    Hi Justin,

    At 720rpm it is 16.50kg/hr.

    Ron
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  4. 30th April 2011, 06:41 PM #4
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    Quote Originally Posted by RSCHIPP View Post
    Hi Justin,

    At 720rpm it is 16.50kg/hr.

    Ron
    Ron, should be closer to 22-25. I reckon the MAF will fix it

    JC
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  5. 3rd May 2011, 06:07 AM #5
    phuma Guest
    See here for more readings to compare with: http://www.aulro.com/afvb/discovery-...ngs-d2-v8.html
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  6. 4th May 2011, 07:19 PM #6
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    New MAF installed

    My new MAF sensor, along with other goodies, arrived today. I have cleared the fault codes and will see what happens.

    At idle today there ws no real difference between the old and the new sensor. At 680 rpm thy were both indicating approx 13.50kg/h. I did notice that the aircon unit made a difference to the reading. The figure above is with the aircon unit turned off.

    So far no new faults have been logged.

    Cheers
    Ron
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  7. 4th May 2011, 08:05 PM #7
    phuma Guest
    Is this a new genuine Bosch MAF, or a "pattern" one? It's interesting that it is also lowish at idle. If you switch the aircon on the ECU usually compensates with engine revolutions and the revolution go up - hence the higher kg/hr that you then see.

    Please also post values for higher RPM?
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  8. 4th May 2011, 08:08 PM #8
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    Quote Originally Posted by phuma View Post
    Is this a new genuine Bosch MAF, or a "pattern" one? It's interesting that it is also lowish at idle. If you switch the aircon on the ECU usually compensates with engine revolutions and the revolution go up - hence the higher kg/hr that you then see.

    Please also post values for higher RPM?
    That is the reason I only use Genuine MAF, Td5 and V8's.

    JC
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  9. 5th May 2011, 07:12 PM #9
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    The new MAF is a Bosch one, identical to the original, in all respects.

    Just logged the same fault codes on the start for the drive home today... (What I should have said was, it chimed on the start for home, when I got home I read the fault codes.)

    Upon reading the codes again it may actually mean that bank2 is faulty and the second code is the generic adaptive fault. This could mean that I have a suspect O2 sensor.

    The application of the aircon unit affects the indicated air flow, the RPM does not change. I would assume that the bypass air is adjusted to keep a steady idle RPM. The idle RPM is more affected by the engine temp, i.e. a fast idle when it is cold.

    Scratching my head.
    Ron
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  10. 7th May 2011, 11:50 AM #10
    PhilipA
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    How old are the O2 sensors?
    They only last about 130KK.

    Regards Philip A
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