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p38 diesel auto hot start fix

Discussion in 'Range Rover' started by gra177h, Feb 12, 2008.

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  1. gra177h

    gra177h New Member

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    hi all
    i bought one of these hot start fixes off ebay, it was the cheaper one (reley and resister) it cured the problem of starting , but now the motor is only doin 14 to the gallon and it also puts the tick over up,so i thought i would take it off,but when i took it off and put the motor back to normal i have a problem now that it is not changing gear properly, it is getting up to near 4 thousand revs before it is changing gear, if i put the resister back into the wires that it is linked to ,(the temp sensor wire) it changes gear as normal , but the tick over is still high. can any one help me.is the temp sensor linked to the rev limiter that makes it change gear?
    thanks guys grant
     
  2. wantaquad

    wantaquad Active Member

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    Simple problem - when you have the relay fitted it is not de-energising once the engine has fired up - the wiring is incorrect - either the diagram or the wire you have tapped into.
    If you look at the main hot start fix thread you will see lots of others have had the same problem.
    The best hot start fix includes a timed relay either programmable so that you can play with the settings or a fixed time lapse.
    My advice is to either get a timed relay like in an old diesel escort from a breakers or buy yourself a programmable relay - if you message me I will give you some details.
     
  3. gra177h

    gra177h New Member

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    Hi Wantaquad
    Is There Anyway I Can Put It Back To Normal For Now?
    Thanks Grant
     
  4. redrrover

    redrrover Member

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    hi Grant i had the same problem I have the relay fiited and it did all the things yours did I just pulled the live feed off relay and its back to normal .I then had a psi power box fitted this is a must I now get 31.9 mpg on a run and 25.8 round home . i changed all spill off pipes from injecters it starts ok Pete
     
  5. ultimatez

    ultimatez New Member

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    what is the actual propper cure for this fault? or is there one as alot of people seem to do the relay adaption method but what is the actual fault as i just wonder if all the hassle is just to save time effort or money ??? just a thought
     
  6. wantaquad

    wantaquad Active Member

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    Hi Grant,

    You Can restore it by removing all of the wiring that came with the kit and re joining the wire that runs from the temp sensor to the ECU

    Also to Ultimez

    The original fault seems to me to be down to the programming by BMW - the fault is common to all BMW 2.5 Diesel applications not just Range Rover but Vauxhall Omega too. BMW programme the system so that when the engine is warm it gets NO preheat NO timing advance and NO extra fuel to help it start. Once the engines "get on a bit" like all of us they need a little help to start that BMW do not give - all the fix does is tell the engine it is cold whilst the relay is energised and that it is at the sensed temperature once the relay is de energised. The reason that Chipping the engine works is that the chip bypassess most of BMW's programming and tells the Pump to deliver the fuel you request with the accelerator regardless of what the German engineers think is just enough - that little bit of help - and of course better power delivery at differing profiles - remember BMW did not want the P38 to out perform the X5 they were working on at the same time......
    Hope this helps
    Wantaquad
     
  7. ultimatez

    ultimatez New Member

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    many thanx wantaquad weirdly enough i work for (ptwooee!) bmw and we do get a few m51 engines in with similar faults and usually its down to injectors being replaced ive also noticed that only rr seem to use a bosch variant for the injection management as opposed to bmw and vauxhall that both use dde managment which yet provided by bosch is as you say programmed by bmw so in thoery would a plug and prey box over a complete reworked ecu do the same for curing the fault ?
     
  8. wantaquad

    wantaquad Active Member

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    Hi Ultimatez,

    yep - its the plug ins I have experience of - the hot start fix costs a lot less than chipping. also as mine has quite a few miles on - 134k - I wouldn't chip it in case the extra stress buggers her up... that said a mate of mine has a plug in chip on a 145+k motor with no worries, except if you dont keep the revs up when you pull off it is a little easy to stall it especially when towing.

    Hope this helps Cheers
     
  9. ultimatez

    ultimatez New Member

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    cheers wantaquad :)
     
  10. ians127

    ians127 New Member

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    Hi guys, don't want to get in the midddle of a good relationship! What the F**k cures the problem, as my P28 2.5 DSE is recording 20mpg with the timed relay set up, although it goes like stink - well for a P38 2.5D anyway. Can only dream of that sort of mpg. Cheers, Ian.
     
  11. manhuwa

    manhuwa New Member

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    hie guys

    does the timed relay work on the BMW 5 Series Diesel, E39 1997 model, i see most instructions are for the range rover, where on the e39 can the relay be fitted, mind you the battery is at the back of the car
     
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