07 sprinter limp mode

Discussion in 'Engine' started by Robsx, Jul 9, 2017.

  1. Robsx

    Robsx New Member

    Messages:
    11
    Joined:
    Dec 17, 2011
    Location:
    Atherton, Manchester
    Car:
    ML
    My sprinter went into limp mode with a p0404 code.
    Just changed the egr (second hand).
    Vans now out of limp mode, but didn't sound right on startup (exhaust note). It ran fine for 10 minutes and then started smoking (grey). Any help advice would be appreciated.
    Cheers

    Sent from my EVA-L09 using Tapatalk
     
  2. OP
    OP
    Robsx

    Robsx New Member

    Messages:
    11
    Joined:
    Dec 17, 2011
    Location:
    Atherton, Manchester
    Car:
    ML
    Hi, really could do with some help with this pllleeeeease!
    changed EGR again, ran fine again and then died on me on the test run? all the dash lit up and coasted to a stop. Turned the key and it struggled but started. On the way back it was ok, then a sudden drop in power, like a nose dive, then back to normal and back to a drop in power (limp) all the way back home. plugged it back in and low and behold P0404 AGAIN!!!!! what else apart from the egr could be causing this?
     
  3. Tuercas viejas

    Tuercas viejas Hardcore MB Enthusiast

    Messages:
    478
    Joined:
    Mar 26, 2017
    Location:
    Denver
    Car:
    landrover/rolls royce/MB AMG S600/Prius
    Well you need to post some live data info to be sure!
    But!
    Try to understand this.
    You have a thermo couple (sensor) downstream of the EGR cooler and you also have a similar one at the back of the square section cooler near to the turbo.

    With the PCM monitoring the temperature fore and aft it determines together with the MAF sensor input, the operation of how much the EGR valve is going to operate. Which incidentally can be seen on a decent scanner in YES Live Data!

    Now temperatures roaring off the turbo are in the region of 450c plus . BUT this is too high to be ingested into the inlet manifolding! Then on the other hand if the cooler is plugged up with carbon then you will only get a small amount of super hot poorly cooled gas shooting through the cooler and upsetting the programming of the EGR operation which the PCM interprets as an EGR fault.
    Make sense?

    The most likely remedy is to remove the cooler tear off the end castings and clean out the carbon!

    Caution not an easy task!

    Dealers simply replace it.
    I have in my shop a tank of some very nasty chem carburetor cleaner that strips out carbon. However before that two day soak I /We dunk it in hydrochloric acid (read nasty stuff).

    After all that we powerwash the core to remove the carbon and refit it!

    Now you are still not done yet!
    Replace the EBP sensor (exhaust back pressure sensor) almost likely to be plugged with carbon. Its the shiney big sensor one at the back of the cooler with a spark plug like socket on it .

    Now look at the shiney right angled shanks of the thermocouples, there will be small part numbers etched on the side --check with the dealer because since 2007 there have been a number of supersession to improve EGR performance and reaction.

    OK its back together!
    With a scanner in live data in KOEO status read off the major sensors! , They should all be within 25 HPa of each other.

    Then read of the ambient intake temp sensor (buried inside the MAF sensor) versus the charge temp sensor again the tolerance is 5 dgc . If there is a huge drift in the reading disconnect the MAF socket. If they come into similarity change out the MAF sensor!

    Lastly don't forget the DPF!
    Again in KOEO read of the differential pressure sensor and the EBP which of course is just upwind of it. Again that sensor has been superseded! Observe the label on the body! The latest and greatest part number should read # A 642 etc NOT a 600 etc .
    All, the best
    Tuercas Viejas
    Bringing Gloucester /Zummerzet /Iowa old style farm boy solutions for small problems!:thumb:
     
  4. OP
    OP
    Robsx

    Robsx New Member

    Messages:
    11
    Joined:
    Dec 17, 2011
    Location:
    Atherton, Manchester
    Car:
    ML
    Thanks for all the info, looks like I have a busy day ahead
     
  5. Tuercas viejas

    Tuercas viejas Hardcore MB Enthusiast

    Messages:
    478
    Joined:
    Mar 26, 2017
    Location:
    Denver
    Car:
    landrover/rolls royce/MB AMG S600/Prius
    If you are going to tear into it be mindful of the EGR transfer tube from turbo exhaust Y pipe casting to the cooler end casing.
    Prone to cracking and detachment, it will also affect how the vehicle runs and discharge exhaust gases into the engine bay.

    Note the two 6 x 12 mm bolts that hold the pipe to the cooler are S/S bronze coated. Don't be tempted to use anything else otherwise you will have a rapid detachment problem down the road & more problems.
    All the best T/V
     

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