Hi,
has any one come across the problem of fuel starvation/light misfire under load with a TD5 disco? yet it starts on the button with no problems, Fault code reader came up with MAP sensor not reading any air flow and EGR stuck open,- tested dynamically and fault code reader confirmed, replaced AFM/MAP sensor, symptoms improved but only marginlly, disconnected EGR vacum pipes and blanked off to keep ecu happy, again road tested and symptoms remained the same, under hard acceleration, or full load, hesitation/misfire as if its running out of fuel, LR dealer suggested tank units have caused this symptom - tried a new tank unit, fault remains. and yes the fuel filter was the first thing I tried. I have looked at the poor starting threads regarding the filterhead/non return valve, but this thing starts really sweetly, I have also checked the injector wiring loom harness connections and they are clean and dry Anyone got any more ideas?? Cheers, Mark

waste gate seized on turbo ?

Markt4425 said:

Hi,
has any one come across the problem of fuel starvation/light misfire under load with a TD5 disco? yet it starts on the button with no problems, Fault code reader came up with MAP sensor not reading any air flow and EGR stuck open,- tested dynamically and fault code reader confirmed, replaced AFM/MAP sensor, symptoms improved but only marginlly, disconnected EGR vacum pipes and blanked off to keep ecu happy, again road tested and symptoms remained the same, under hard acceleration, or full load, hesitation/misfire as if its running out of fuel, LR dealer suggested tank units have caused this symptom - tried a new tank unit, fault remains. and yes the fuel filter was the first thing I tried. I have looked at the poor starting threads regarding the filterhead/non return valve, but this thing starts really sweetly, I have also checked the injector wiring loom harness connections and they are clean and dry Anyone got any more ideas?? Cheers, Mark

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your post said fault code showed map sensor was not working, im i reading your thread right and you have changed map sensor, or have you changed maf sensor or both?

sorry Johnlad, my typo, maf sensor, but Brainbee diagnostic was happy with reading after changing and clearing fault codes, dynamic test also showed air flow and variation through out parameters, and fault code did not return after road test. Turbo seems to be boosting ok James, but I have not yet put a boost gauge on to test boost pressure under load. I know the old tdi's used to suffer from internally collapsing turbo/intercooler flexipipes which gave similar symptoms but they seemed to be more generally DOP under hard acceleration as soon as the turbo started to boost, this thing seems to be boosting fine upto about 2500rpm, then will flutter and lose power, if you accelerate gently it will get upto about 2750 - before symptoms kick in

turbo can over boost and upset ecu parameters unlike tdis

when misfire happens, if you switch off and re start does it drive ok upto same revs then fault appears, if so could be going into limp mode, through overboosting as James said, i believe they have a boost modulater fitted which are pretty cheap, maybe worth changing it

Cheers guys, I will investigate further and keep you posted, Drekkly Mark

....EGR stuck open....disconnected EGR vacum pipes and blanked off

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^^^ be more specific here please... u mean u've disconnected the vacuum pipes and blanked off the exhaust pipe but did u make sure that the open valve is closed now? ... cos if it's still stuck open mechanically or due to accumulated muck u still dont have enough air going through the intake manifold cos the open EGR valve is limiting the pure air....remove the EGR valve and clean it well then make sure it's closed when u put it back. I suppose u have the Euro 3 type cos u said "pipes" so make sure the ILT valve is completely open cos this one lets the air in.

IMO u better do the complete mod and put that "tube" instead of the EGR... and clean the intake manifold aswell.... then, if no improvement we'll speak about other management issues

Quick update guys, TD5 sorted, used a freinds sykes pickavant code reader and got turbo overboost fault flagged straight away, also EGR now stuck closed!! no suprise there as its disconnected at present. I investigated further and found that the waste gate was indeed stuck shut, so freed off and squirted a drop of UHT spay grease into the spindlebearing, cleared fault and road tested, found fault stayed off and pulled cleanly again, picked up a slight hesitation at around 2750 rpm, so by passed modulator valve with a straight connector, tried it again and found clean smooth acceleration right the way through the rev range. ordered a new modulator valve and fitted it this evening, road tested again fault stayed off and and smooth acceleration/power all the way through the rev range A nice cheap fix really, its just a pity that works BrainBee diagnostic did not pick up the overboost, as that would have saved me trying a fuel lift pump never mind I now have a spare to keep in stock for if it does play up! thanks for your input and thoughts, I can now concentrate on adding all the toys that the wifelet wants fitting to it!!