406 Hdi intermittint bad idle/ surging on low power

[rossd]

From your cold start video your rail pressure is all over the place. When I start mine, it sits at 312bar for a minute or so and then drops to a rock steady 298bar, with 17% OCR on the pressure regulator. (These figures are perfect btw!)
I would suggest yours either has a gummed up pressure regulator or the high pressure pump is getting tired. The pressure reg can be removed from the back of the HP pump (although its not the easiest thing to do with the pump on the car) and checked for any dirt \ crud on the tip. If you do remove it, keep it clean

[patrickgledhill]

Hi Rossd, thanks very much for your input! Yesterday I fitted a new new common rail pressure sensor (replaced under warranty thank god). it seems to be running heaps better but time will tell of course.
Tonight ill get the computer on again and do another video to check those figures, its great to now have some to compare with!
With a dirty regulator can i just clean that with brake cleaner or such and refit?

your input is much appreciated!
cheers, Pat

[patrickgledhill]

Well things are better but the issue is not solved as of yet. I had the regulator taken out and cleaned, the chap said it had a bit of corrosion on it and said that it may have had some contaminated diesel at some stage! I hope that's not the case. Anyway since that was cleaned and the pressure sensor replaced the car is starting and running better. However on start-up the diesel pressure is still varying and under any acceleration apart form full throttle i can hear a resonating in the exhaust as if the diesel pressure regulator is still fluctuating/slow to adjust. I think im looking at a replacement regulator. In the meantime the egr is still disconnected because that fluctuates. Is it hard to do a vacuum test on the system?

cheers, Pat

[patrickgledhill]

Hi guys, I'm going to drag this topic back up because I'm still having a surging sensation sometimes with light acceleration. Reading back up these posts it's was mentioned that my measured diesel pressure is varying quite a bit (assuming not normal). The diesel pressure regulator mA current also varies should this be stable as well?

It hasn't stalled after startup since I replace the seals on the tip of the diesel pressure reg.
Like I've mentioned I'm my latest topic post I've had the speed sensor fault pop up ( could this be linked)
The erg valve remains unplugged because this was opening and closing all over the show and hurting the fuel economy.

So there are a few factors here I'm not sure about
The fuel pressure all over the show
Pressure reg % varies a bit ( is the current supplied supposed to be steady)
Egr unsteady, no obvious vac leak and I've tried swapping the soliniods over
The engine speed sensor ( crank shaft sensor) what role does this play
Leak back on cyclinder 3 has been as bad as 3 mm3 while driving.

Nothing like a good mission

Cheers team

[Peter.N.]

Its just occurred to me that you mentioned 'hunting' I had this problem with my C5 2.0. Hdi and it turned out to be caused by the pressure regulator on the HP pump or rather the filter in it. The regulator is easy enough to remove, two screws and a plug, when you take it out you will notice a stainless steel looking tube projecting from the end, this is the filter and its very fine. I did find one from another pump that didn't have the filter so I removed it from mine and its been fine since, the easiest thing to do is grind the end off, making sure you remove all the swarf of course.

Mine was also difficult to start when hot but this regulator seems to produce a variety of problems, when I removed mine it had small shards of metal sticking out of the filter which I assume was due to the in tank pump failing so I changed that as well.

Peter

[patrickgledhill]

Hi Peter, thanks for sharing that, Ive had that regulator out and replaced the orings but I cant remember that filter tip. Ill wip it out tonight and report back.
Is grinding the end of the only way to remove that filter?
The intank pump did fail about 3 years ago so this is sounding promising
Cheers,
Patrick

[Peter.N.]

I broke the filter off mine but then it wouldn't fit properly so I had to add an extra 'O' ring. Maybe yours doesn't have a filter, see the link, the filter is the silver bit sticking out.

http://www.ebay.co.uk/itm/FUEL-PRESSURE ... 2335863993" onclick="window.open(this.href);return false;

Peter

[patrickgledhill]

Hi Peter,

I took out the regulator and, no filter. mine has a white spacer, and a green oring on the tip.
i gave it a good spraying out with solvent cleaner into the litte hole on the side and what have you.
Its back in and it started fantastically, driving great and a fairly steady bar pressure of 298 moments of 300. idle 803.

these are links to pics of the regulator and the pp2000 parementer readouts.

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Cheers

[Peter.N.]

Yep, that's like the one I had.

Peter

[patrickgledhill]

For some reason I doubt its going to run nicely for much more than a few days.. has anyone cleaned these semi submerged in an ultrasonic bath?
I'm tempted to just bite the bullet and grab a new one.

Patrick

[patrickgledhill]

Hi Guys, I purchased a new Bosch regulator from Lithuania off ebay, $170 NZD, It arrived in one week! and it had free shipping very happy with that.
Anyway, ive installed the new part and the car is running like a dream, start idles and accelerates very smoothly. the new one had the filter on the tip
Cheers for your help! very appreciated

Patrick

[Peter.N.]

Good to hear, also nice to hear the Lithuanian ones work - just in case.

Peter