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jabajawsx2

New Member

• Oct 23, 2011

• #1

Hi all
Could some body point me in the right direction to the sensor that tells ecu what pressure the low pressure fuel supply is on a 2003 td4 thats the one with the pump under the wheel arch. many thanks

 

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Vissie

New Member

• Oct 23, 2011

• #2

Inside the n/s/f wing...... on the fuel pipes.

 

J

jabajawsx2

New Member

• Oct 23, 2011

• #3

thanks for you reply vissie thats the one i thought. Now this is were i get lost when i disconnect this sensor it makes no difference to the performance at all, but i do get the engine management light on. should it not stop the engine ??.

 

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Vissie

New Member

• Oct 24, 2011

• #4

What performance difference were you looking for?

EML flags up to say 'lowside fuel pressure plausibility fault'.



Lowside fuel pump isnt variable, its either on or off. So there is no way for the fuel pump to detect anything about it. It cant even tell if its running or not, so the way in which it detects fuel pressure is by the sensor inside the n/s/f wing. If the fuel pump goes down or the fuel filter blocks, it just flags the above fault of pressure plausibility. Thusly it doesnt matter in terms of engine performance if the fuel pressure sensor is connected or not, as the fuel pump works from ignition 2, even before cranking.



Hope that answers your question, im not sure , since i dont know why you want to unplug the sensor

 

Chaser

New Member

• Oct 24, 2011

• #5

when the Lp sensor detects low pressure the ecm limits injection to allow limp home, if the pressure falls even further (to 0.5bar?) it will stop the engine.

disconnecting the sensor will show as an open circuit fault because you have removed the sensors supply voltage

 

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jabajawsx2

New Member

• Oct 25, 2011

• #6

Thanks peeps now should it go into limp mode or not when i disconnect the sensor ???. secondly when it was in the garage a year ago plugged into t4 one of the readings was that of the low pressure supply which i believe should be over 300 kpa at all times, which sensor gives the ecu this reading ?? thanks

 

Chaser

New Member

• Oct 25, 2011

• #7

Perhaps you should post the fault symptoms so we know what your trying to achieve.

Lp supply pressure is measured at the sensor you are looking at.

I don't think disconnection will result in anything other than a sensor fault code. Ok it can't give any reading at all but ecu could default to checking for an adequate Hp reading.


At what rpm did you get 300kpa? if it was at idle then that's barely enough and will likely drop below 200kps at full throttle.
It should give a 1260 fault code.

 

J

jabajawsx2

New Member

• Oct 25, 2011

• #8

Fault first : i have been suffering from poor performance i.e. when stud i can rev the engine and the limiter kicks in but when i am driving it, it struggles to pass the 3500 rev range and generally lacks power. i also notice lots of smoke in the mirror at night when i it the peddle.It also starts first time from hot or cold.
This is whats been done:
New fuel pump and filter: new maf: new boost pressure sensor: turbo as been refurbished: all new vacuum pipes: oil and filter change: new filter in depression valve: and i have replace the engine harness:
So my thinking is that the low pressure fuel is under pressure causing the ecu to cut the high pressure pump. i may be totally wrong. I dont know what the low pressure pump is delivering now as my mate no longer works for l/drover and i have spent enough on it now, so i solo

 

Last edited: Oct 25, 2011