This Scv Thing

[dognobbler]

Hi all

Just aquired a 2.0 D4D which has been thrashed to within an inch of its life so am trying to give it some tlc. Main problems are turbo boost pressure fault (code 1250) and loss of power/surging at 3000 rpm.I have been browsing around a while and see it is a common fault. I have ultrasonically cleaned VRV and EGR valves and light has stayed out for a few days but still the power loss. Connected my scanner up and noticed common rail pressure seems a bit low when revving, about 650 bar at 3000 rpm , does any one of you guys know what the pressure should be and also do the scv valves have an effect on the pressure.

Great forum btw

[anchorman]

Welcome to the club.

I can tell you that the SCVs do control fuel pressure but I'm afraid I have no values for the 4.2.This pdf shows how to check them but they usually stick mechanically and not electrically;

m_fu_0014.pdf

[dognobbler]

Thanks for that anchorman. I have now removed SCV valves , gently blown em out and put them back and for some reason fuel pressure has gone up and rav runs better . Don't really know why that would be. Do you know how these valves work?

[anchorman]

They are basically a pair of power operated valves that can be varied to restrict the flow of diesel through the high pressure pump. They vary the fuel pressure in the common rail. Another good reason for using good quality fuel? I hope they remain in good working order but don't be too disappointed if they stick again.

I recently saw and bought a pair of brand new ones off eBay for £60 so my mate Wollaston now has them in his garage as spares for his. I see they are up at £230 ish now. It pays to snap up a bargain