Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 27

Thread: Weak Td5

  1. #11
    Join Date
    Nov 2008
    Location
    Bruthen, Eastern Vic.
    Posts
    836
    Total Downloaded
    0
    Check your fuel pump.
    Engine will draw enough fuel to run with a non working pump, but not above 3000rpm.
    Good luck, and welcome.
    Terry
    80 109" 2.6 P ex Army GS, saved from the scrappie.
    95 300tdi 130 Single cab tray.
    2010 Guzzi 750

  2. #12
    Join Date
    Dec 2015
    Location
    Sweden
    Posts
    8
    Total Downloaded
    0

    Now, this is strange...

    @sierraferry: Yes, I replaced the small (and unreasonably expensive) filter under the FPR, and also the fuel filter behind the wheel, which I change regularly. The tires are not oversized, and I have checked and lubricated the wastegate actuator arm which indeed was stuck and I thought I'd found the problem but no difference. The new fuelpump is not a VDO, but today I connected a pressure monitor to where the fuel temperature sensor sits in the FPR and the pressure is well above 4 bars, almost 5 even when driving at high load uphills, no decrease at all in the pressure monitoring. BUT: strangest thing, with the pressure monitor connected It was performing wonderful, could even accelerate uphills! So, I put the fuel temp sensor back and the problem was back... disconnected the contact from the sensor and Voila! Perfect preformance!!
    Bad sensor or something corrupt in the ECU. I am suspecting the ECU since I also found an error message from the gearbox: "P1884 CAN MESSAGE MD_IND INVALID" (no other errors), and strange Engine temp data from gearbox:

    It never goes above 53 degrees...

    So now I'm contemplating how to proceed? New temp sensor? New ECU? Other Ideas? Are there any negative effects driving without the temp sensor connected?

  3. #13
    Join Date
    Apr 2016
    Location
    Melbourne
    Posts
    4,203
    Total Downloaded
    0
    So you disconnect the fuel temp sender, and it goes good.
    Reconnect the fuel temp sender and it goes bad.
    But you're getting engine temperature values from the gearbox temp sender?

    Is this an OBDII tool you're using to get this data, or the nanocom?(looks like nanocom, but need to ask question).

    I'd say drive with the fuel temp sender disconnected for a while and see how you go.
    But before you condemn the ECU, pull some stuff off around it and triple check the wiring loom to the ECU for damaged parts or shorts.

    My brother's TD5 had an issue a while back and I thought it was ECU related. So when searching on the issue I found that damaged ECU looms are not so uncommon.
    Maybe the wire from the fuel temp sender is cross contacting with another wire before it gets to the ECU and therefore the ECU gets corrupted or scrambled data.

    Alternatively: when you changed the fuel pressure regulator, did you change the entire assembly or did you rebuild your old one with some new parts(eg. regulator/o-rings/gaskets etc) and keep the body of the assembly including the temp sender?
    I think many people assume that when you do the FPR, you buy the new assembly in it's entirety, which means an entirely new body, hoses .. ie. an entirely new part, which includes the temp sender.
    If you used your old fuel temp sender to rebuild your FPR, maybe the sender is dead, giving a high reading on the fuel temp and confusing the ECU?
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  4. #14
    Join Date
    Dec 2008
    Location
    Yatala Vale, Adelaide, SA
    Posts
    340
    Total Downloaded
    0
    Red herring first - the temperature reported in nanocom for engine temp from the gearbox is rubbish. I have *no* idea where it comes from but it is never the actual engine temp. There is also no temperature sensor on the gearbox.

    The error message on the box I see quite often on most of the D2s I've hooked my nanocom to, it usually indicates a low voltage at some point - I swear the box can log a fault during cranking....

    It sounds like you have the fault found though, check the fuel temperature in the TD5 engine section of nanocom, I'm guessing it is reading high and so the ECU is reducing the fuel being fed in because of the perceived temperature. Disconnected the ECU just assumes a default value.

  5. #15
    discorevy is offline ChatterBox Silver Subscriber
    Join Date
    Nov 2014
    Location
    Nirvana near Albany W.A.
    Posts
    2,356
    Total Downloaded
    0
    Ditto eng temp from gearbox values, its just a reference value.
    You can swap eng temp sensor with the fuel temp sensor to eliminate that ( clean first :-)

  6. #16
    Join Date
    Dec 2015
    Location
    Sweden
    Posts
    8
    Total Downloaded
    0

    Temp sensor ok?

    I read values with Nanocom Evolution. From what I've found, the Engine temperature reported from gearbox is received from the engine ECU and is used by the gearbox to determine if it's warm enough to engage lockup.
    My fuel temperature sensor seems to give correct values?:

    ...and the coolant temperature follows the same curve. When disconnected the fuel temp value defaults to 60 degrees.
    I'll have a closer look at the cables

  7. #17
    Join Date
    Oct 2012
    Location
    UK
    Posts
    66
    Total Downloaded
    0
    The temp senders don't normally fail outright, they tend to flatten off with age reporting values lower than reality, typically 10-20C less. At least when using Bosch parts.

    For the coolant sensor this normally manifests as increased fuel consumption.

    I've not had a problem with the fuel sender yet, but would imagine it would not retard performance in this failure mode (on a manual at least!) - looking forward to seeing the outcome of this investigation though as I'm not sure how/if the auto ECU uses the fuel temp information and whether this is actually a wiring issue.

    If you've got a multimeter to hand you can test the sensor by setting it to resistance (~20kohm) and referring to this datasheet to approximate temperature from the output -> http://www.bosch-motorsport.com/medi...2569739pdf.pdf

  8. #18
    Join Date
    Apr 2017
    Location
    Adelaide
    Posts
    14
    Total Downloaded
    0
    If you believe your problem is the ecm, replace all of the power feed and earth wires running to the ecm. You don't need a loom, just replace them individually. I haven't had it on a Td5, but too many times to count on trucks.

  9. #19
    Join Date
    Dec 2015
    Location
    Sweden
    Posts
    8
    Total Downloaded
    0
    @BennehBoy

    I think you are right. According to the Nanocom manual, fuel temp should be about 10 degrees below coolant temp, mine measures approx. 30 degrees below. The fuel temp is used by the ECU to calculate fuelling so this might be it! I have ordered a new sensor, not so expensive and since I've replaced everything else....
    Will update when I've replaced it.

  10. #20
    Join Date
    Oct 2012
    Location
    UK
    Posts
    66
    Total Downloaded
    0
    Fingers crossed.

Page 2 of 3 FirstFirst 123 LastLast

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!