2.0 HDI 138 rough in idle and lower gears

[JackoJuaquo]

Hi all,

Hoping someone may be able to point me in the right direction.
My C5 X7, 2.0 138 is running a bit loud and rough at idle, same in reverse and first, once it goes into higher revs it actually quietens down a lot, it’s very quiet at motorway revs.
Seems to also have basically no power in reverse and first. Kind of odd, thought it might be injectors so I’ve got some new washers and I’m going to perhaps try refreshing the nozzles soon.
One thing that may or may not be a clue is that there is a constant pitch noise in first and second when the clutch is engaged, once disengaged or into higher gears the noise goes. Car has newish clutch and dmf, so I think perhaps it’s just some kind of oddity

My question is, is this just how that engine behaves in general? Perhaps that’s why they changed it so early in the X7s life cycle.

*having just watched some YouTube videos of 138s accelerating etc I can say that mine absolutely does not sound right.

[the-termin8r]

It might be your fuel pressure regulator. They're known to go on this engine. I had mine replaced recently. I didn't have such extreme behaviour as you're describing, but I was getting stuttering around 2k RPM, especially in second. And if I mashed the throttle at motorway speeds it would throw up an engine ECU error and go into a pseudo limp-mode. I made a thread about it, the posts are a bit disjointed as my account accidentally got deleted around then and then there were some forum technical difficulties recently. I think the relevant info (including a link to the part in the last post) is still in there.

[Peter.N.]

My 2.0. has a roughish tick over which also shows up at very low speed, the speed varies and it tries to stall, sometimes does, but otherwise drives like a dream. Works better with the MAF disconnected. Have investigated everything I can think of but with no improvement. Have changed the crank and camshaft sensors, no different although the crankshaft sensor plug went open circuit which caused intermittent starting and eventually no starting.

Peter

[JackoJuaquo]

Think the MAF can be cleaned with some EGR cleaning spray or similar. I'll give that a good check, along with injector cleaning if I ever get the time!