Failing airflow meter on V70 TDI - Symptoms ?

Discussion in 'Volvo V70' started by Nick, Oct 26, 2007.

  1. Nick

    Nick Guest

    I have a 1997 2.5 TDi V70 (diesel), approx 168,000 miles, and wondered what
    the symptoms are if the mass air sensor is failing.
    Do they get dirty and need cleaning ?

    Nick, Oct 26, 2007
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  2. Nick

    Tim.. Guest

    a failed or dirty MAF usually gives the symptoms of the engine goes flat
    just as the turbo spools up- a lack of power over say 2500-3000rpm.

    If unplugging it brings back 85% of the power, then replace it.
    Yes, but cleaning is often short lived.

    Also always replace it with the genuine Bosch article. The cheaper ones are
    cheaper for a reason...

    Tim.., Oct 27, 2007
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  3. Nick

    Nick Guest

    Hi Tim,

    Sounds like it may be what I have - around 2300 to 2700 rpm it is hesitating
    as if the "mixture is wrong"

    Does this sound like it could be the MAF ?


    Nick, Oct 27, 2007
  4. Nick

    Tim.. Guest

    Nick as I said, the usual symptom is a lack of power under load when the
    turbo is spooled and creating extra airflow- the MAF is not signalling to
    the ECU that this is happening, so it underfuels. A clean exahust is also a
    sign - i.e. no trail of soot under hard acceloration.

    Tim.., Oct 27, 2007
  5. Nick

    Nick Guest

    OK - thanks for the reply..

    I don't think I have underfuelling unless it occurs just at this rpm are..
    it seems quite "pokey" at WOT and higher revs,
    although I don't seem to get a visible exhaust trail, just a bit hesitant
    around 2500 rpm and light throttle..


    Nick, Oct 27, 2007
  6. Nick

    Tim.. Guest


    Then check the TPS and more likely the EGR valve. (preferably blank it off

    Tim.., Oct 27, 2007
  7. Nick

    Nick Guest

    I have heard about blanking off the EGR but also rumours that some
    damage might occur, so I haven't. If the only negative might be that
    under some conditions the emissions might be a tad worse, then I am
    OK about it, but I don't want to overheat or in some other way harm
    the lump.
    I guess the TPS is just a pot and a multimeter across the terminals
    to check for smooth / progressive operation is what needs to be seen

    Nick, Oct 27, 2007
  8. Nick

    Tim.. Guest

    No harm at all, infact usually more responsiveness at smaller throttle
    openings, better MPG, less soot, and alot less bunging up of the intake
    system with soot, that you have to clean out.
    Yes- exactly.

    Tim.., Oct 28, 2007
  9. Nick

    Nick Guest

    Great ! Thanks,

    I will have a go later then.

    Nick, Oct 28, 2007
  10. Nick

    HAL9000F Guest

    Will blanking the EGR off cause the Check Engine light to come on?

    HAL9000F, Nov 1, 2007
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