Intermittant limp mode on bumpy roads

Discussion in 'Tech/Mech General' started by Bigjr, Jan 24, 2016.

  1. Bigjr

    Bigjr Funster

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    My 2001 Ducato 2.8jtd does not like bumpy roads! It occassionally goes into limp mode and then the red injector warning light comes on. This may last for a few seconds then everything goes back to normal for a while - possibly just for a few yards or over a hundred miles!
    The autoelectricians and Fiat dealers who have looked at it claim to have found insufficient error code information using diagnostics as (a) the fault is intermittant and (b) the ECU has only a 2 wire diagnostic plug. At their suggestion I have replaced the accelerator pedal assembly, replaced the ECU and had all the wiring connections checked including the injector plugs - all with no improvement to the problem.
    Can someone please tell me if the engine goes into limp mode quickly followed a second or two later by the injector warning light coming on, does this mean the is fault connected with the injectors or could this particular warning light come on because something else has caused the engine to go into limp mode?
    I would be grateful for any comments - I feel like driving the MH over a cliff sometimes!
     
  2. Phill D

    Phill D

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    i think on aerly ECU models that the injector indicator is the main warning light for limp mode. it certainly is on some 2001 / 2002 Ford vans.

    so it does not necessarily mean an injector fault.

    if its on bumpy roads is it as simple as a loose plug or chaffing wire....
     
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  3. pappajohn

    pappajohn Funster Life Member

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    Inj warning light can be anything on the inlet side....air flow sensor, air temperature sensor , fuel pressure sensor etc.
    You need a proper code reader to pinpoint the exact sensor.

    I never heard of a two wire OBD socket, even early ones were multiple wire with oddly shaped sockets.
    Since around 2001 (from memory) they have a standardised socket and multi wired.
     
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  4. Figaro

    Figaro Funster

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    Not a techie so can`t help sorry, but just when we get one "intermittant limp home mode" problem resolved, another comes along to challenge us !
    We feel your pain and hope you can get it sorted with the help of the knowledgeable people on here.
    Chris
     
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  5. Larby

    Larby Funster

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    Try wiggling the wires going to the injectors. Some had trouble with leads a bit too short and could be poor contact?
    As Pappajohn questions, 2 pin ?
    The 16 pin plug is located to the right of steering column if my memory serves me correct behind a cover

    EDIT, I may be wrong

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    Re: diagnostic port. 2001 2.8jtd
    Hi Guys,
    found it! It's a 3 pin connector with only two wires and is under the bonnet near the ecu. Will post a pic of it and give details on how to connect to an elm327 interface. I've managed to get my laptop to talk to the ecu but the software I have is unlicenced so it won't tell me what the error codes are for the problem I have. I've downloaded some more freeware s/w and hopefully one of these will do the job, will let you know.
    Keep well,
    Torq
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    Last edited: Jan 24, 2016
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  6. Bigjr

    Bigjr Funster

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    Yes my diagnostic plug is the oval 3 pin type with 2 wires feeding it (1 pin is unused)
    I have got one of the adaptor leads from Ebay to link the 3 pin plug to the 16pin lead on a standard diagnostic machine.
    But some Fiat main dealers (no names!) have refused to use the adaptor in case it "affects the integrity if their diagnostic machines" !

    Pappajohn, thanks for your reply. Are you suggesting that an Inj warning light is more likely to be a problem with one of the sensors you mention rather than a loose wiring connection? I had presumed the latter as the problem only occurs on bumpy roads
     
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  7. gus-lopez

    gus-lopez Funster

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    Have a look at the brake light pedal switch if it has 2 sets of connections for normally open /normally closed , usually on vehicles fitted with cruise control , then it could well be that . Mine used to do it on rough roads. Could be not adjusted correctly or, what mine was, the continual release of the pedal was causing the centre pin to knock the plastic switch part backwards & opening up the metal tags that held it on. So creating a bigger gap & the vibration on a rough road would operate the brake lights & as your foot is on the throttle , after a few seconds it would go in to limp mode.
     
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  8. Bigjr

    Bigjr Funster

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    Many thanks everyone for your suggestions. I now think the problem lies in the plug on the lead that fits onto the throttle potentiometer. I have used a couple of cable ties to tightly bind the plug to the outlet pins on the potentiometer and this has helped but not cured the problem completely.
    Can anyone suggest a Ducato dismantler who may be able to supply me with a secondhand plug with 6" of wiring attached from an old wiring loom? I could then cut off my defective plug and join up the replacement one.
    I can't find a supplier who can sell me a new plug to suit without buying a whole new section of wiring loom.
     
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  9. Steve

    Steve Funster Life Member

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    I have had this fault in the past, it is a common one. In my case it was the wire/plug to the No. 4 injector. Took a while to find as intermetent. Hope this helps and saves you a lot off time.
    Steve
     
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  10. Bigjr

    Bigjr Funster

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    Thanks Steve, I had heard of this probem from another posting but after checking out my injector leads/ plugs this didn't seem to be the problem.
    A Fiat specialist has been able to get an error code from the limited info available from the 3 pin diagnostic plug suggesting the fault lies in the circuit to the throttle potentiometer. The throttle pedal and ECU have been replaced and the wiring checked for corrosion, chaffing, etc, so the fault seems to be within one of the connector plugs.
     
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  11. DavidG58

    DavidG58 Funster

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    I cant offer you any technical support, but having suffered a similar issue for months, until fixed last month, I share your woes, I considered the cliff options as well

    I hope you do find a solution, I know how maddening intermittent issues are, mine was a Mercedes with a totally different issue, but hopefully you are close to sorting it now yourself

    Best of luck (y)
     
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  12. andy63

    andy63 Funster

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    The confusion over the diagnostic plug is most probably because the vehicle is 2001... although the 16 pin socket was found before on commercials I think it was 2007 when it became mandatory...
    Hope it is what you suspect... but if not the battery connections and earth worth a look...If that hasn't already been done .
    Ta andy
     
  13. finyar

    finyar Read Only Funster

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    I had the same issue and it was the no 4 injector lead, this is a common problem and results in the van going into limp mode.

    Not very funny in my case as I was half way up the hair pins in Alpe d'heuz.
    Fiat even sell a replacement spare connector to allow you lengthen the lead as this is what causes the problem

    As said earlier it can be intermittent and apparently has to do with heat and resistance in the cable
    Raymond
     
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  14. Bigjr

    Bigjr Funster

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    I have at last found a local garage man who has been able and willing to retrieve the fault codes from my MH's 3 pin diagnostic port. After checking and cleaning all likely earthing points, plugs and connectors he re-set the ECU and took the vehicle for a test drive. All was ok for the first few miles but then a bump in the road triggered the limp mode symptoms again. A further diagnostic test showed fault codes PO220 (throttle pedal position sensor 2 circuit) and PO500 (vehicle speed sensor). As both these fault codes have always appeared simultaneously on this and subsequent tests it would suggest that there is a connector or section of faulty wiring that is common to both these circuits.
    I have been unable to get my hands on a wiring diagram that would show details of this shared connector or faulty section of wiring. Is there and auto-spark out there who could offer some advice?

    John
     
  15. denisejoe

    denisejoe Funster Life Member

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    When we had that happen it was the wiring to the injectors. Fiat make them too short but don't admit a fault. The new loom is longer! It did go into permanent limp mode eventually so had to be replaced.

    Joe
     
  16. Bigjr

    Bigjr Funster

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    Joe, Thanks for your reply.

    Several others on this site have have had problems with too short wirind to the injectors. If this problem puts the van into limp mode the ECU must be putting out a fault code? What fault code would suggest this is my van's problem? I don't think codes P0220 and P0500 I refered to above are related to this problem

    John
     
  17. denisejoe

    denisejoe Funster Life Member

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    Don't know any fault codes as it was fixed on warranty.

    Joe
     
  18. hilldweller

    hilldweller Funster Life Member

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    I don't know if anyone else has suggested this but get it running, bonnet open, and whack everything in sight with a stick, not too violently to see if you can cause the fault.
     
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