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Thread: Td5 EGT spikes - how to confirm EGT probe is not faulty?

  1. #1
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    Question Td5 EGT spikes - how to confirm EGT probe is not faulty?

    Three days ago, on Tuesday, my Td5 D2a became fairly limp as the EGT alarm sounds when it's slightly pushed. The EGT are rising scarily fast.

    The car seems to have the normal power levels and response.
    The boost gauge shows that the turbo charger is spooling up fine and boost levels are normal.
    Fuel economy seems to be normal (which is surprising as to achieve higher EGT I would have though the fuel mix would have to be richer?).
    EGT at idle sit in the low 100*C.
    Cruising at 60km/h on flat roads ranges from 250 - 350*C.
    City driving, when pulling off, might get up to 450*C briefly.

    But if I try to get up to highway speeds or drive up an incline the EGT fly up. Pulling onto the highway with the accelerator pedal only pushed halfway I will see 400, 500, 600, 700, 800, 900, then overrange all within 2 seconds or so - this is on roads that I regularly travel and never have EGT issues on. Is it actually even possible for the engine to produce such levels of heat in such a short time?
    Backing off the accelerator pedal just 10mm or so can see an almost instant sudden drop back down to 400-500*C. Then pushing it down another 10mm will see it fly back up. During all this the vehicle will be barely able to hold its current road speed!

    I'm wondering if there is a fault with the EGT monitor, wiring and/or probe due to the drastic sudden movements in temperature. The exhaust manifold and turbo charger don’t seem abnormally hot after driving. Is there a way to test the probe or is it a case of replace the probe to see if that’s fixed it?

    Of perhaps relevant note is that I undid and removed the EGR blanking plate that the EGT probe is mounted into about a fortnight ago - perhaps this has disturbed/upset the wiring which has become quit rigid and hard in the time that it's been installed since 2011...
    Mine - modified MY03 LT L318 Discovery 2a HSE Td5 15P
    Hers - MY12 L319 Discovery 4 2.7L TDV6
    Dads - MY12 L319 Discovery 4 2.7L TDV6
    Sister-in-laws - MY98 LJ Discovery ES 3.9L V8

  2. #2
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    IMO rapidly increasing EGT’s can be caused by restricted air in or out.
    Check for internally delaminated turbo or inter cooler hoses, a blocked air filter or inter cooler or a blocked exhaust (cat or silencer)
    Phil B

    Custodian of:
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    1978 S3 swb canvas
    48 749 '88 4x4 Perentie
    1985 County with 4BD1T

  3. #3
    discorevy is offline ChatterBox Silver Subscriber
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    probably probe , try loosening it then retighten in a slightly different spot , if still the same you may need to replace it.
    what brand and what is max boost level with your vgt ?

  4. #4
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    Quote Originally Posted by discorevy View Post
    what brand and what is max boost level with your vgt ?
    Turbo Technics Stage 2 Hybrid - S208 - 180HP supplied by Bell Auto Service (BAS). I can get up to 21psi of boost.


    Quote Originally Posted by Phil B View Post
    IMO rapidly increasing EGT’s can be caused by restricted air in or out.
    Quote Originally Posted by Phil B View Post
    Check for internally delaminated turbo or inter cooler hoses, a blocked air filter or inter cooler or a blocked exhaust (cat or silencer)
    Will do, but I've got Roose Motorsport silicone hoses so they should delaminate like the factory hoses.
    If the air filter, air intake, intercooler or exhaust were blocked I would have expected some noticeable effect on the vehicles performance too? It's worth checking though.


    Google brought up this thread on 4x4community <
    https://www.4x4community.co.za/forum/showthread.php/231959-MADMAN-EMS-egt-Probe-problem >, seems like the guy had a similar issue and it was caused by the earth connection. It's been 8 years since I installed it so I can't remember where it's earthed but I was working in the dash under it the other month when I changed the headhunit so perhaps I disrupted something then.
    Another discussion on it at < Td5 Exhaust Gas Temp major issue?? > but doesn't give a conclusion on how it was resolved.
    Mine - modified MY03 LT L318 Discovery 2a HSE Td5 15P
    Hers - MY12 L319 Discovery 4 2.7L TDV6
    Dads - MY12 L319 Discovery 4 2.7L TDV6
    Sister-in-laws - MY98 LJ Discovery ES 3.9L V8

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    The problem has worsened. It’s now reading 400 to 600*C at idle - sometimes even higher! I turned the vehicle off the other day, turned accessories on and it was still claiming 1,000*C for EGT!
    Given that I’ve continued to drive the vehicle to work and back each day (taking it way but still) I’m confident that there’s no truth in the readings as the engine has yet to melt.

    I’ll check for earth issues over the weekend otherwise Jan Dppenaar of Nata Enterprises has quoted $49.00 delivered for a replacement EGT probe which I’ll order if the no earth faults found.
    Mine - modified MY03 LT L318 Discovery 2a HSE Td5 15P
    Hers - MY12 L319 Discovery 4 2.7L TDV6
    Dads - MY12 L319 Discovery 4 2.7L TDV6
    Sister-in-laws - MY98 LJ Discovery ES 3.9L V8

  6. #6
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    Quote Originally Posted by twr7cx View Post
    The problem has worsened. It’s now reading 400 to 600*C at idle - sometimes even higher! I turned the vehicle off the other day, turned accessories on and it was still claiming 1,000*C for EGT!
    Given that I’ve continued to drive the vehicle to work and back each day (taking it way but still) I’m confident that there’s no truth in the readings as the engine has yet to melt.

    I’ll check for earth issues over the weekend otherwise Jan Dppenaar of Nata Enterprises has quoted $49.00 delivered for a replacement EGT probe which I’ll order if the no earth faults found.
    Interesting!
    please let us know what happens when you change the probe
    a photo of the old one would be good as well.
    thanks
    Phil B

    Custodian of:
    1974 S3 swb wagon (sold)
    1978 S3 swb canvas
    48 749 '88 4x4 Perentie
    1985 County with 4BD1T

  7. #7
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    New probe in and temps are back to normal.

    For anyone else in the future note that the Jan Dppenaar / Nata Enterprises replacement probes wiring colours differ to the standard - details in < Jan Dppenaar / Nata Enterprises new replacement EGT probe wiring colours >.
    Mine - modified MY03 LT L318 Discovery 2a HSE Td5 15P
    Hers - MY12 L319 Discovery 4 2.7L TDV6
    Dads - MY12 L319 Discovery 4 2.7L TDV6
    Sister-in-laws - MY98 LJ Discovery ES 3.9L V8

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