Engine & Gearbox The EGR debate - to block or not to block?

Discussion in '3rd Generation (2006-2012)' started by agadza, Wednesday 7th Sep, 2016.

  1. agadza Club Member ★ ☆ ☆ ☆ ☆

    United Kingdom Agadza London
    I am confused about the EGR debate.
    Some seem to swear that blocking it does the engine a lot of good. It is really only for environmental reasons, nothing to do with performance they argue.

    The other school of thought argue differently, indeed some claim a clean EGR has improved their MPG on diesels.

    I also read on youtube that the I-CDTI engine was designed with EGR technology in mind and that it in effect has two of these.

    My mate has blocked his on his BMW 525d and is all excited about the increase in performance. I am tempted, but thought it wise to ask on this forum first.

    Can anyone shed any light?

    Thanks in advance.
  2. Zebster Guest

    At an accelerator pedal position greater than 50% the standard map closes the EGR valve anyway, at least on the I-CTDI, so no peak performance gains are possible (people who have done something to their car love to rave about how they've managed to get improved performance, but I think it's usually a placebo effect).

    Mid-accelerator MPG should improve a little from blocking EGR but at the expense of vastly-increased NOx emissions, and NOx is a very nasty local pollutant that has recently been at the centre of the VW/Audi scandal.
    agadza, chunkymonkey and Lisbon like this.
  3. Nels Moderator Staff Team

    Removing the valve or blocking of the system is a modification to the vehicle. All modifications must be reported to your insurer. Failure to do so will invalidate your insurance. I'm not sure what effect it will have on your MOT.

    The EGR system is there for a reason, to reduce the amount of harmful pollutants in our air.
    Increased NOx emissions will cause a worsening of asthma and in some cases bring on an attack that will kill the asthmatic.

    IMHO, these vehicles should be confiscated and crushed. The driver should also have to spend a week on a ward and see how terrifying a asthmatic attack can be.

    But that is just my opinion.

    Please don't modify the EGR system. Just ensure it is clean and operating correctly.
  4. Zebster Guest

    I'm unsure of the legality of disabling a vehicle emission control system, even though there are unscrupulous remappers offering this service. But it is unlikely to be spotted, so they get away with it.

    Blocking the EGR increases the exhaust gas temperature, which could have a negative effect in engine longevity?
    agadza and Nels like this.
  5. agadza Club Member ★ ☆ ☆ ☆ ☆

    United Kingdom Agadza London
    Many thanks, all!
    Will be leaving well alone. Very good points raised in the discussion, quality advise.