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The Dreaded Misfire

Discussion in 'TD5' started by sabredylan, Jun 12, 2011.

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  1. sabredylan

    sabredylan New Member

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    Hi everyone

    I'm new to both Land Rovers and the site, so please excuse my lack of knowledge.

    Recently acquired a td5 Disco 2 auto. I've had a vibration when the auto box changes gear, which is usually around 2500 revs. I thought it was a transmission fault at first, but after searching and reading threads, I became aware of the oil in the loom problem. I checked mine and low and behold, there was quite a bit of oil in the red plug. I cleaned this out along with the plug itself. What a difference, I couldn't believe how smooth the gear change was and the vibration had gone..........or so I thought!!!!!!

    The engine was like silk for about an hour, but then the vibration came back. I checked the ecu again and there was a bit of residual oil, but nothing like the amount I found initially. So to cut a long story, the vibration came back and I can't get rid of it. You can feel the vibration in neutral when you hold the revs between 2000 and 2500. You can drive through the vibration and it seems to smooth out, but easy driving and light throttle, its very apparent. It is still misfiring.

    During a journey earlier in the week, the disco was misfiring/vibrating on gear change. I had to nip to the shops, but on returning to the Disco after a short time, it ran like silk again for about 3 miles.

    My hands are full at the minute, with a new baby, so I'm unable to do any involved jobs. With this in mind, I purchased a new injector loom and rocker gasket from paddock, and took the disco to a local independent specialist. I told the mechanic to fit the injector harness and even got him to seal around around the plug connector with rtv.

    I went to collect the disco yesterday and took it for a test drive. The vibration is still there. I held the revs at 2500 again and could feel the misfire. I returned the disco to the mechanic, who plugged in some fancy comm device. He checked injector or cylinder deviation and found at idle all was fine. On revving and holding at 2500 revs, cylinder 3 and showed negative deviation, cylinder 5 being the worst at up to -9. The mechanic says he will have to get all the injectors tested.......More expense.

    This is what I've done so far: -

    -Cleaned ECU plug and loom - made a huge difference for about an hour, but misfire
    returned.
    -Cleaned map sensor - no effect
    -Cleaned Maf sensor - no effect.
    -Checked and oiled wastegate actuater arm - no effect.
    -Changed and sealed injector harness - no effect.
    -Had new in tank fuel pump.
    -Had full service, with all filters changed, engine flushed and auto box oil changed.

    There is no engine check light and the only fault code that came up was something like too slow for cruise control, even though I don't use it.

    I can't help but think that the problem is something starring me in the face. After initial ecu cleaning the disco ran like a dream and has ran well since albeit for only a few miles. For this reason I'm loathed to get into a few hundred pounds having the injectors messed with, just to find its not the problem. To me if an injector is bad, it would be bad all the time.

    Can any of the site gurus give me any ideas on something I've missed or where to look before having the injectors checked?????

    Sorry for the long post, but just want to give as much info as possible

    Many thanks in advance
     
  2. Shifty1962

    Shifty1962 Well-Known Member

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    I'd check the main ECU earth point. Make sure its clean and tight. Failing that keep cleaning out the ECU plug(s) until there is no sign of oil contamination. The oil will still be in the main loom for a while. You can use aerosol brake cleaner as it dissolves and flushes the oil and dries with no residue.
     
  3. sabredylan

    sabredylan New Member

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    Cheers for the reply.

    I'll check the earth point. Would it be worth opening the ecu?
     
  4. ZippyIII

    ZippyIII Member

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    Hi
    Reading your faults you were told that a -9 was bad, well you may need to get a second opinion as when I was in the garage watching the injector screen I was told that a minus number was good? Somebody on here may know the correct answer. A second garage told me the same and with the TD5 if one injector fails the ECU will try to compensate with the others. I have had lots of faults (TD5 Cut out and will not start)and being of "Old School" I think that its one of my injectors is at fault, away being tested now. Hope this may be of some use to you.
     
  5. sabredylan

    sabredylan New Member

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    Cheers for the replies.

    Took disco to 4x4 mechanic as in previous post. Told him to check all the wiring and ecu, before he starts swinging on the injectors. They are a last resort.
     
  6. Shifty1962

    Shifty1962 Well-Known Member

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    You can open the ECU and CAREFULLY clean out any oil inside the unit. Make sure its not connected to any power and use an earth bonding wristband if you are touching the circuit boards. The components are easily damaged by static electricity. As are all delicate electronics.
     
  7. sabredylan

    sabredylan New Member

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    Had mechanic on phone today. Said he'd tested the injector wiring and opened the ecu. No oil had got inside and no breaks in wires. He said heis going to get the injectors tested. Out of interest, is there any way to test the ecu?
     
  8. ZippyIII

    ZippyIII Member

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    Sorry I gave you duff info I said -9 was good, what I should have said was under 10 was good. Have you cured your problems yet ?
     
  9. 50 pence

    50 pence New Member

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    Do not read too much into the individual injector " balance/roughness " figures, if they,re out they,ll be +/- 20/30/40/50/60/70, and if the ECU cant " adapt an injector or it becomes too far out of " range " for the ECU controll, then it will log a fault.

    Taking injectors out is relatively easy, but is time consuming and can, if not done carefully, lead to all manner of other issues from over tightened bolts to dirt contamination.

    I was wrongly led to belive that I had a duff injector, so I took it out to get it tested, and it was fine. While at the testing place, I asked the manager if he tested many TD5 injectors, to which he replied, " we get sent set after set for testing, and only ever have a few that fail ".

    Shifty mentioned the earth wire, which reminded me, have you checked your battery,s condition, as a failing battery can cause all kinds of trouble.

    Del.
     
  10. sabredylan

    sabredylan New Member

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    Sorry not replied. Car is still at the garage!!!! I'm getting a bit miffed to be honest. I like doing my own repairs, but can't at the minute because of lack of time. Mechanic couldn't find anyone to check the injectors. It took me all of two minutes on the web, picked the injectors up and took them myself to Diesel Bob in Preston. Had them re calibrated and pressure balanced, but Bob said they wasn't greatly out. £300 lighter and I bet its not the issue. Could have been worse as they are £300 each to replace. Dropped the injectors back off with the mechanic, so I'll find out tomorrow. I still feel its an electrical fault, but I can only rely on what the mechanic is telling me. At least I know its not the injectors now. Even got some new adjustment screws and asked for the old ones back, so I know the lash has been reset. If its still the same I'll be kicking off royal.

    I found this diagram which may help some people.

    td5 loom.jpg

    I'll be checking all the wires myself when I get it back. I've been thinking of making my own injector loom, using solid core wires and soldering it to the connectors. I'll update you more when I get the vehicle back.

    Cheers
     
  11. Shifty1962

    Shifty1962 Well-Known Member

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    You need to make sure the mechanic puts the injectors back in the right cylinders. ie. the ones they came out of. I bet he did not record which one came from where. If you're lucky and its still attached the sticker on the cam cover will tell you which one goes where. If not then you really need a Nanocom or similar to see which injector code the ECU expects in which cylinder. Having said that if you've had them overhauled then the injector codings will be wrong anyhow.
     
  12. Kentishcolin

    Kentishcolin New Member

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    Hi,

    Made my own loom up after finding the dreaded oil in the plug problem.
    Changed the injector loom with the extra rvt gasket sealent added, then identified all the wires using the colour codes and a multimeter, left myself enough wire to sensibly strip back from the red plug and injection loom plug and soldered in a new loom. Used heat shrink tubing to cover the soldered joints and also bought in some convoluted sleeving to finish the job off.

    My reasoning behind doing this ....... a couple of hours work was well worth not having to wait for the oil to make it's own way out of the old loom possibly taking weeks to do so.

    Got my wire , heatshrink and sleeving from AES (auto electrical supplies ltd)
     
  13. The Mad Hat Man

    The Mad Hat Man Well-Known Member LZIR Despatch Agent

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    What did yu do about the sensor wires? Did yu get the AWG all the same?
     
  14. sabredylan

    sabredylan New Member

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    well bit of an update......

    Got the truck back from the mechanic and it was running rougher than when I took it in. The mechanic has had it three weeks, so I was just glad to get it back.

    The injectors have been cleaned and calibrated and replaced with new seals and washers. The engine feels more lumpy at idle now and the misfire is still there, but now at 1900 revs. I did notice the pump making a loud noise, whining and the sound of the diesel racing as if there is air in it. There is also tapp/knock on the engine, which wasn't there before.

    I decided to change the fuel pump, filter and regulator with Land rover items. Let the fuel system prime, the pump ran its cycle about 5 times and you could hear the air rushing around the filter. The pump finally quietened and I started the engine. Smooth as silk, fixed? so I thought!!!!!

    Went for a spin and all seemed ok. Called for some fuel and on switching the ignition again, the pump is loud again and the sound of air in system. Let the pump prime again and again it went through its cycle several times. started the engine and it knocked and a big cloud of black smoke out of the exhaust with the tapp/knock back again. Obviously fuel getting into the cylinders

    so this is where I'm up to, as well as pulling my hair out.
    Where do I go from here??

    - Has the mechanic ballsed the injector seals?
    - Is the head cracked?

    I really need some advice.
     
  15. changill

    changill New Member

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    Bit of a late response to your query, but if you still have a problem and want to use my Nanocom you are welcome. (I'm West of Garstang)

    Chan
     
  16. johnlad

    johnlad Well-Known Member

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    is that west of garstang nr blackpool, cos if you dont mind i wouldnt mind checking my injectors are in the correct positions
     
  17. changill

    changill New Member

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    Yes John,

    I'm Over Wyre.

    Drop me a PM if you want to use the Nanocom.

    I've checked and recoded injectors in the past.

    Cheers

    Chan
     
  18. Davidmac

    Davidmac Member

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    Hi there I have just bought a Disco Td5 and took it round to see the mechanic at my local mot station who has had discos for years he informs me that when the dreaded misfire happens you change the harness and then its off to landrover dealer to reset the ecu.Sometimes ur lucky and the oil in the ecu drains out with no lasting probs and sometimes ur not an the reset's the only option dont know if this helps.
     
    Last edited: Nov 1, 2011
  19. jamesmartin

    jamesmartin Well-Known Member

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    normally you replace injector loom in rocker box and clean both ends of other with suitable spray cleaner and go,keep cleaning loom end s till its dry after a few days you can tell if its the problem by undoing connector at front underside of rocker box if its oily replace loom,doesnt need resetting
     
  20. Shifty1962

    Shifty1962 Well-Known Member

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    What James says. No need to reset the ECU. Money for nothing.
     
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