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Thread: Td5 overboost issue

  1. #1
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    Td5 overboost issue

    Hi all,
    I have two remaps for the Defender, a stage 1 and 2. Boost has been increased to 1.2 bar with usual rod adjustment. All works well with stage 1 tune according to nanocom. Stage 2, however, will see 1.4 bar and overboost. I've checked wastegate and it appears to be operating freely. The actuator also seems fine and I have purchased a second and tested that against operation of first and concluded they are both working in a similar fashion. I've also check pipework for leaks and nothing detected. Performance is fine except for overboost. I'm going to purchase a VGT/VNT in the new year so not bothered to pull turbo for further inspection. I'm more interested in understanding possible causes.

    Peter
    1951 Series 1 "Lights through grille"
    1973 Range Rover Classic "Suffix B"

  2. #2
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    Hi Peter,

    Lots of good very technical background reading that may help here:. Eg this

    Overboost Fuel Cut Map | DiscoTD5.com

    Cheers
    Simon
    Cheers

    Simon
    2003 D2a TD5, ACE, SLS, Vienna Green.

  3. #3
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    Quote Originally Posted by simonmelb View Post
    Hi Peter,

    Lots of good very technical background reading that may help here:. Eg this

    Overboost Fuel Cut Map | DiscoTD5.com

    Cheers
    Simon
    Very technical indeed! Looks like a good source of information. Thanks, Simon.
    1951 Series 1 "Lights through grille"
    1973 Range Rover Classic "Suffix B"

  4. #4
    discorevy is offline ChatterBox Silver Subscriber
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    There could also be the simple reason in your case that the "stage 2" tune is driving the turbine side of the turbo harder, causing the overboost .

    Assuming these tunes are both "old school type", and in a Defender which doesn't have a boost modulator.

    option 1: Lengthen the rod by 2 turns when "stage 2" is in or

    option 2: fit a good quality manual boost controller

    option 2 will allow easier adjustment and you will also be able to use it for the VGT.

    "New school" or torque based tuning done well is the go when you do fit the VGT.

    Shack on here has the VGT tune pretty sussed

  5. #5
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    Quote Originally Posted by discorevy View Post
    There could also be the simple reason in your case that the "stage 2" tune is driving the turbine side of the turbo harder, causing the overboost .

    Assuming these tunes are both "old school type", and in a Defender which doesn't have a boost modulator.

    option 1: Lengthen the rod by 2 turns when "stage 2" is in or

    option 2: fit a good quality manual boost controller

    option 2 will allow easier adjustment and you will also be able to use it for the VGT.

    "New school" or torque based tuning done well is the go when you do fit the VGT.
    I've got 2 ecu's, the stage one on msb and stage 2 modern remap on a nnn. I've also lengthened the rod to various stages in the hope of avoiding overboost without success. My thought is perhaps wastegate not opening fully and hence why I said I won't bother removing turbo to check. My assumption here is if wastegate opens fully it should not overboost. Perhaps that's not the case.

    Peter
    1951 Series 1 "Lights through grille"
    1973 Range Rover Classic "Suffix B"

  6. #6
    discorevy is offline ChatterBox Silver Subscriber
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    Are you able to clarify whether the NNN unit is :

    1, Using the Torque based tuning method ?, this is the most modern method of tuning and superior as it allows the tuner to rescale sensor parameters.

    2, Running dedicated EU2 files for your engine?, the NNN unit, while more modern and flashable needs to run the correct files for the earlier system.

    Does your Nanocom list overboost or out of range Maf reading faults?.
    The later EU3 tables use Maf info

  7. #7
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    Quote Originally Posted by discorevy View Post
    Are you able to clarify whether the NNN unit is :

    1, Using the Torque based tuning method ?, this is the most modern method of tuning and superior as it allows the tuner to rescale sensor parameters.

    2, Running dedicated EU2 files for your engine?, the NNN unit, while more modern and flashable needs to run the correct files for the earlier system.

    Does your Nanocom list overboost or out of range Maf reading faults?.
    The later EU3 tables use Maf info
    Hi Discorevy,
    how would I go about clarifying 1 and 2? Can the nanacom be used? The remap is from Storm if that helps with clarification. I will check tomorrow as to whether nanocom lists those faults.

    Thanks for your help,
    Peter
    1951 Series 1 "Lights through grille"
    1973 Range Rover Classic "Suffix B"

  8. #8
    discorevy is offline ChatterBox Silver Subscriber
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    Hi Peter

    I'm not sure which method that tuner uses but probably safe to say most bigger name tuning companies would have adopted some ( or all ) of Paul's ( offtrack, the link simonmelb provided ) methods in the last 5 years.

    If you asked them to specifically do the tune for your vehicle and variant etc then your problem may just be high reading maf sensor. ( if new method, then it should have been rescaled so may be the actual sensor fault )

    If you bought the ECU pre tuned ( maybe for something else, later model for eg )then it won't work correctly with yours.

    Can you post a log?

  9. #9
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    Quote Originally Posted by discorevy View Post
    Hi Peter

    I'm not sure which method that tuner uses but probably safe to say most bigger name tuning companies would have adopted some ( or all ) of Paul's ( offtrack, the link simonmelb provided ) methods in the last 5 years.

    If you asked them to specifically do the tune for your vehicle and variant etc then your problem may just be high reading maf sensor. ( if new method, then it should have been rescaled so may be the actual sensor fault )

    If you bought the ECU pre tuned ( maybe for something else, later model for eg )then it won't work correctly with yours.

    Can you post a log?
    Will post a log tomorrow.
    The tune was purchased by me and specific for vehicle so hopefully all good there. I was given impression that it was a mechanical issue such as wastegate or a boost leak but thought it strange it is only with this tune. A sensor issue makes more sense.

    Peter
    1951 Series 1 "Lights through grille"
    1973 Range Rover Classic "Suffix B"

  10. #10
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    Found an old log but not showing when overboosting.

    BOOST1 3.xlsx
    1951 Series 1 "Lights through grille"
    1973 Range Rover Classic "Suffix B"

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