EGR valve v new turbo

[Benscab123]

This may seem like a duplicate post to my last one, but I’m going to try and word it differently in the hope I’ll get a more simplified answer .

So, when I bought the car it had an EGR fault code P0405, changed the EGR (for a used one) then the fault changed to P0401 insufficient flow. Left it as was until last week when the turbo failed ! Replaced the turbo with an eBay copy and after fitting and running it for a day, I’m getting fault code P0299 underboost. Cleared both faults but they both return each time I try.
Could the EGR fault have anything to do with the turbo fault or vice versa ?
One thing I have noticed is that there is a small amount of oil pooling ontop of the actuator (not sure where from).
Before fitting the new turbo we cleaned out the sump and removed the oil strainer, fitted a brand new oil feed pipe (although the new pipe seems to fit a little too close to the actuator rod for my liking).
My thinking (and I’m no mechanic) is that the pipework to/from the EGR May have become blocked (it wasn’t checked when EGR was replaced).

I’m at my wits end with this car right now , so ANY help would be much appreciated, but please try to answer in layman’s terms as I’m not too savvy with the technical jargon.
Thank you.
P.S. Marc has been exceptionally helpful so far, but I’m struggling with this one .

[GiveMeABreak]

I'll just add a further thing here as simple as I can.

The only other thing I can think of with the Turbo is the vacuum circuit. The electrovalve number (5) in the circuit below.

You've already identified oil - that may be the oil lubrication pipe not fitting properly (or wrong part supplied) or the seals. But I though to mention that if the vacuum circuit is not providing sufficient air, or the filter on the electrovalve is blocked - that can affect the operation of the Turbo.

Key:
A: External pipe.
B: Duct internal to the engine.
C: Air.
D: Exhaust.

Reference	Designation
a	Coolant Inlet
b	Coolant Outlet
(1)	Exhaust Gas Recycling (EGR) Regulation Electrovalve
(2)	Air Cleaner
(3)	Air Flow Meter - Air Temperature Sensor
(4)	Vacuum Reservoir
(5)	Turbocharging Pressure Regulation Solenoid Valve
(6)	Exhaust Gas Manifold
(7)	Catalytic Converter - Particle Filter (FAP)
(8)	Air/Air Heat Exchanger
(9)	Butterfly Double Air Metering Device
(10)	Exhaust gas recycling (EGR) Heat Exchanger
(11)	Air Inlet Manifold
(12)	Turbocharger

[Benscab123]

Cheers Marc I’ll take a look at that.

[RichardW]

The actuator on the turbo should press down easily and the return smartly with the engine off. If you watch it as the engine is started the vac should pull it down. If it doesn't then either a vac fault or a problem with the turbo. Assuming that you refitted the vac pipe when you did the turbo....

[Benscab123]

I’ll check that too, thanks Richard.

[admiral51]

"One thing I have noticed is that there is a small amount of oil pooling on top of the actuator (not sure where from)."

I think the oil will be coming from the oil feed pipe directly above the actuator, from memory it has a strange way of sealing, i think Marc posted in your previous thread but if you look back at the Devil Car link in the other thread Mike T had issues with the feed pipe sealing.

Thinking logically, and as it is not a regular service item, the car is close to 10 years old, i would look at changing the Solenoid Valve item 5 in the pics above.
Again i refer back to the Devil Car link purely as i had the same fault code and remember the Turbo actuator needs a vacuum to operate correctly.
Mike T replaced the Solenoid Valve and he also looked at the old one and the filter on it was black and clogged, everything is linked so a problem with a vacuum issue will impact elsewhere

[admiral51]

Question what is fault code P0401 insufficient flow?

[GiveMeABreak]

I've posted the explanation for that fault here Colin:

viewtopic.php?p=624348#p624348

[admiral51]

Thanks Marc i missed that

[admiral51]

If i have read the diagram correctly item #9 is the air doser, the double butterfly valve that i had on my old C5 now with Mike T( not sure if you have the Vin for that still Marc)
If the air doser butterfly valves are sticking could it cause the fault P0401 ie it works most of the time but when it sticks it could allow more/less air than expected ?
I still think the main issue is #5 the solenoid valve, once that is sorted i think it should be easier to narrow down other issues

[Benscab123]

What I don’t understand is , there was no underboost with the old turbo. Apparently that died of oil starvation.

[admiral51]

What I don’t understand is , there was no underboost with the old turbo. Apparently that died of oil starvation.

May seem like a few daft questions and as most people on here know i ask a lot of them but................

How certain are you that there was no underboost on the old Turbo ?
Reading back through other threads you had an issue with cruise control, i assume you also have an issue with the speed limiter, does it work sometimes and then just drop out, unable to set either until you switch off and on ?
Do you still have that problem ?
Did the old Turbo throw its toys out of the pram or were you told the Turbo was knackered ?
The Actuator will need to be removed and refitted to replace the Turbo was it correctly reset.

Only asking as i had similar issues with a 1.6 HDI Turbo and the issues you are having are so familiar to what i had.

Oil leak was from the oil feed pipe
Air Doser was knackered
Vacuum Solenoid blocked
Actuator was working but replaced to be safe.

I knew as soon as the Cruise/Limiter went offline i had code P0299, didnt even need to check i knew it would be there.
Cannot remember which fault related to which part, will need to double check the Devil Car thread, but both Air Doser and Solenoid were changed along with Actuator so time line of which fault was cleared first i cannot remember.

Also at the same time i had the Particle Filter risk of blocking message, but all the time it was regenerating as requested, Mike T told it it had a new DPF and light went out

[Benscab123]

My mechanic told me the turbo was knackered after I broke down one day last week, car lost power and couldn’t get above 40mph. It’s had brand new turbo and actuator. The problem with the old turbo was OVERboost , cruise would disable itself whenever the turbo overboosted. New actuator came already attached and preset.

[Benscab123]

The old turbo was covered in thick black carbon deposits, so assumed oil starvation.

[GiveMeABreak]

The oil starvation is very likely to have been the problem - important not to mix the issues here, as there is clear evidence of carbon / sludge build up in the turbo as seen by Benscab.

But I think you may need to look further at the cause - which could of been down to poor maintenance by the previous owner. If there are heavy sludgy carbon deposits as a result of blocked oil channels like in the cylinder head - then ultimately the same thing is going to happen again.

Have a look here for some information and also the video is very good:

https://pmmonline.co.uk/technical/tackl ... di-engine/