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TD5 bad start

Discussion in 'TD5' started by Mario110, Jan 26, 2020.

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  1. Mario110

    Mario110 Member

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    Hi all,

    I've got a Defender TD5 MY 2002 15P more than a year ago in bad condition. The engine had diesel in oil and a huge maintenance backlog. Today, there are only two things left, but they are driving me crazy and sometimes I think of selling the car because of this.

    First thing is that the is engine knocking in certain temperature frame, which was also discussed here some time ago. It looks like that this knocking is getting better on every long ride. The knocking is just for information not the topic here.

    The biggest issue: When engine was not running for a long time, it doesn't start like a TD5 should start. For me, a TD5 (this is my second one) is starting when you show him the key - every time. ;-)

    In past, it took several tries to start. It was really difficult, took something around a minute. ECU was has logged a noisy crank shaft signal. I've found out that the pre-owner has changed the main gear box and during this task, destroyed the CKP connector (not the CKP itself). The repaired cable gets my attention and I read somewhere that the polarity is important for the CKP signal. Can somebody confirms this? I was assuming that the zero crossing was the information and not the polarity.

    Anyway, after changing the polarity, the engine starts better - sometimes like a TD5 should do.

    Over time and other repairs, the behavior becomes different. The engine was not starting at the first time, but perfect after the second try - everytime.

    Last weeks, I've changed DMF and the starting behavior was changed again: I have to crank the engine for something around 5 to 10 seconds , then the TD5 was running for 2 - 3 seconds not on all cylinder and then it's running.

    All of these starting issues are on the first run. If the TD5 was started and running on all cylinders, I can stop it and start it again like the TD5 should start. After some minutes/hours the behavior get's worser and it is like I described above.

    I got the noisy crank shaft signal again, so I had a closer look yesterday on it:

    upload_2020-1-26_8-24-50.png

    The workshop manual says:
    • 2 to 3 volts with engine cranking.
    • Rising to 6 to 6.5 volts from 1000 rev/min upwards.

    Not sure how to interpret this information. My CKP signal is in idle between 2 to 3 volts and going to 4 volts at 1000 rev/min and has nearly 6 volts at 2000 rev/min, during start it has below 2 volts.



    Besides of that I've measured that the injectors are triggered somehow even when it's not starting at the first time. So, I'm not sure if the CKP is the root cause.

    During my repair journey, the following parts are changed: AMC cylinder head, refurbished injectors, fuel pressure regulator, battery, starter, fuel pump, diesel filter, diaphragm valve, glow plugs and a lot more...

    The engine runs smooth and pulling is good, there is no smoke. Although the error is similar to worn out injector seals, but I cannot hear any noise from the fuel pump.

    Currently, I'm somehow lost. There are no TD5 specialists in near which can have a look in the next time...

    What can I do next?

    Thank you in advance.
    Best Mario
     
  2. JimS

    JimS Well-Known Member

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    Hi
    All I can suggest is a new senor swap out and if it works keep the old as a spare, it seems like you have tried most everything
    The occasional dirty signal from the sensor would make me wonder if there is some kind of intermittent resistance problem with the sensor or the connector
     
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  3. Mario110

    Mario110 Member

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    Yes I can just swap the CKP...but I'm not sure...

    I've tried one more thing today: Before start, I've let the fuel pump run for some minutes and start the engine with pulled down throttle pedal. As far as I know this will enable the bleeding mode of the injectors. The engine starts after 2 secondes well with the first try and running on all cylinders immediately with some smoke.

    I forgot another open topic, I had some air in the diesel system in past and "fixed" this temporarily with cable ties (the left one "fixed" the issue, the other are only to be on the safe side):

    upload_2020-1-26_12-7-26.png

    Could it be possible to have some air in the system without noise?
     
  4. Discodevon

    Discodevon Well-Known Member

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    Hello, some td5 crank sensors have a spacer fitted, to allow for a larger gap between the flywheel and the sensor itself, some starter motors cause a bad signal to, maybe try a bump start?
     
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  5. potus

    potus Well-Known Member

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  6. Si Click

    Si Click Well-Known Member

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    That CKP sensor looks in pretty poor shape, the O ring seems to have vanished for a start and there is what appears to be swarf next to the sensor itself. I would start by replacing with a genuine one.

    You said the connector and possibly the wiring was damaged; if so that could cause a fuzzy signal and poor starting. The polarity of the two internal wires to the ECU is important - and you should check the continuity of each between the CKP connector and the ECU red plug. You should also ensure that the shielding is correctly connected in the ECU red plug.
     
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  7. Mario110

    Mario110 Member

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    Thanks a lot so far. I will try a bump start tomorrow, this is the easiest I can do.

    Yes there are swarf on the sensor itself and there is a good chance that the spacer was lost....It wouldn't be the first part that was missing. :confused:

    The connector was definitly destroyed and a new one was fitted from a Discovery loom. It looks like the shield is missing, I'm not 100% sure, there was no shield going to the sensor itself, there are roughly 20cm wires to the sensor without a coating...

    The shield is going from the connector (but not the connected to it) to the other parts of the wiring loom? Or is the original connector shielded?

    EDIT: Found this link https://www.lrworkshop.com/connectors/defender-2002my/C0168
    So the shield is inside the black coating and the connector itself has no shield, right?
     
  8. Si Click

    Si Click Well-Known Member

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    Correct, the CKP connector itself does not connect to the shielding, although the shielding should be intact as close as possible to it. The cable has shielding under the black insulation coat so that any electromagnetic interference that impacts the cable is absorbed by the shielding (like a faraday cage I guess) and grounded through the correct connection in the red ECU plug. If you have 20 cm of exposed wires then any interference will induce current in them and confuse the signal. I suspect that your issue may be a combination of a poor CKP sensor and the exposed wiring. If this is enough of a problem that normal background interference from a running engine is sufficient to confuse the signal, then a bump start will probably not work. If a bump start does work then the CKP system, compromised as it is, is still working and your problem is probably massive electromagnetic interference coming from the starter solenoid contacts. A £10 kit will fix this.

    I would put in a genuine CKP sensor in any event as yours looks well past it and as it is the only sensor that will cause the ECU to prevent a start or stop a running engine, it is a critical component. From recent personal experience there is little point buying a cheap aftermarket one as they can be faulty when new. If there is enough flex in the cable to reattach the CKP connector close to the shielding, then do that, but in my experience the loom is made with very little spare cable. I guess it may be possible to shield the exposed cables with proper cable shielding slid over the cables and connected to the existing shielding in the remaining cabling (it needs to ground through the ECU plug), and then shrink wrap insulation over the top. You might even get away with tin foil if it can be connected correctly. The alternative is to use new shielded cable with a new CKP connector routed with physical cable shielding to the ECU plug and wire it in. I did this recently with my son's D90 TD5 and once I had worked out how to replace terminals in the connectors, got the polarity straight in my head and worked out which three connectors in the ECU plug needed to be replaced, it was a straightforward job complicated only by the fact that the new aftermarket CKP sensor I put in was faulty - see my point in buying genuine.

    All this assumes that the CKP sensor is causing the problem you are having. If so a diagnostic check will confirm.
     
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  9. Mario110

    Mario110 Member

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    Update: I've replaced the fuel pipe, don't need the cable ties anymore but starting behavior is still the same. I will try a new CKP although the noisy crank shaft error message is not appear again since some start attempts...
     
  10. JimS

    JimS Well-Known Member

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    If on a cold start you first go through the fuel air purge (ignition, 5 presses on accelerator) and then go to start is it ok?
     
  11. Mario110

    Mario110 Member

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    No this doesn't help, but if I press down the gaspedal during start to bleeding the injectors, then the TD5 is starting around in 2 - 3 seconds and running smooth immediately. If I stop it after that, I can start again within the first second. But if I wait some minutes the issue comes back.
    The longer the engine has been running, the longer it takes for the problem to return. If I wait a day, the issues definitly comes back.

    To be honest, it doesn't sound like the CKP but I don't have any other idea now....
     
  12. Si Click

    Si Click Well-Known Member

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    That is sounding more like air in the fuel. I looked over the list of things you have replaced, but did not see the air bleed valve from the fuel filter housing. Have you replaced that?
     
  13. Mario110

    Mario110 Member

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    Yes I've changed it a year ago, the old one looked like this:
    upload_2020-2-9_17-1-7.png


    Maybe I should check it again. I cannot hear any conspicuous sound from the pump....I don't have the original non return valve, it's only a reduction of the radius, the part which is looking like a duckbill is missing. If I remenber correctly, it wasn't availabe anymore...
     
  14. Mario110

    Mario110 Member

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    Currently the air bleed valve looks like this:
    upload_2020-2-9_17-43-17.png
     
  15. Brown

    Brown Well-Known Member

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    Yes, the fact that it gets more difficult to start the longer it's been standing suggests that the fuel is draining out of the head somehow. Yes, the little white plastic thing you're holding is the air bleed valve. The non return valve is typically a black plastic thing that looks like a small pipe connector and a red rubber duck's bill. Shouldn't be too difficult to renew either component, as a lot of suppliers are selling them separately now.

    Incidentally, I see a Nanocom in one of your pictures. If you can see an rpm figure when turning the engine over on the starter, it's not the starter causing interference. Mine says around 260 rpm as I recall. Because the ecu and Nanocom are working it out from the crank position sensor.

    Don't forget the condition of the wiring loom itself. I have had problems with mine. Especially if someone has pinched it in between the bellhousing and engine block while changing the gearbox.
     
  16. johnlad

    johnlad Well-Known Member

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    I’d renew the injector seals again, only use genuine and make sure injector seat is spotlessly clean.
     
  17. Si Click

    Si Click Well-Known Member

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    Cannot tell much from just looking at it. There is just a membrane there that lets any air bleed back to the tank via the pump, but which stops fuel going back to the tank. If the membrane is allowing fuel through then it will be slowly draining the fuel in the head and could give the symptoms you describe. They are quite cheap, so I would stick another one in there.
     
  18. Mario110

    Mario110 Member

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    Does this mean the white (bleed connection) fuel pipe shouldn't have any diesel in it?
     
  19. Si Click

    Si Click Well-Known Member

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    My understanding is that the air and fuel should be separated by the bleed valve and so the bleed return pipe to the pump/tank should only have air between the filter housing and the pump.
     
  20. Mario110

    Mario110 Member

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    @Brown
    Are you able to read values with Nanocom from ECU during starting? It's not possible on my TD5, the communication stops and I have to restart the Nanocom...
     
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