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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22736
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a dicovery 3 hse 2.7 the engine has been frequently

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i have a dicovery 3 hse 2.7 the engine has been frequently self revving up and down between 1000 rpm and 2.5 when im stationary and also revs self increase when driving sometimes . when stationary with foot off the accelerator the revving up and down can continue for several mins.....any help would be appreciated as it has been in dealers twice and not been fixed both egr valves have been replaced

HelloThis could be a lack of fuel pressure from the electrical pump at the tank.If the connections to this are corroded or damaged then the pump could stop atany time or could not be running at full speed. Check that its relay switchesin and out and the relay contacts are clean and bright – replace the relay ifin any doubt and do the same for the fuse,Ideally measure the pressure at the inlet to the main engine fuel pump and ifthis is low check the pump as described and also consider changing the fuelfilter as if this partially blocked this too will reduce pressure.
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