I have a 2008 C2 with the 1.6 hdi engine, myself and three separate mechanics could not figure this out. When under load the engine light would come on and say 'anti-pollution faulty'.
The boost is totally inconsistent and fuel economy is poor, about 40-44mpg gently driving it. Revving through the gears is ok, there is not much smoke and it boosts fine. Power does not really come on until 2000 rpm.
However, at around 2000 rpm, putting my foot down for an overtake there is no boost and it spews black smoke. If I ease off the throttle, gear down and gently roll back onto the throttle, it is nearly fine and behaves itself higher in the revs. The car boosted ok for the first month I drove it, but now its unpredictable.
Gearing down into 2nd gear, turning off the main road and getting on the power again it totally over-boosted and sent me towards the ditch
My mums last car was a 2008 C5 x7 with the 1.6 hdi. We had the DPF removed and EGR blanked, it was then remapped. It gave better MPG than this C2 which just does not make sense to me, surely the much lighter C2 with the same engine should return better MPG?
That C5 drove beautifully with zero issues for a year after that DPF/EGR and remap work. Anyone else I've spoken to with a C2 VTS hdi says they get 60mpg all day.List of the work done to date in chronological order:
- Previous owner had removed DPF.
- Turbo blew, reconditioned turbo fitted, sump dropped, turbo lines replaced and everything cleaned, wire gauzes in turbo banjo bolts removed.
- New EGR fitted and then blanked, previous EGR melted.
- Injectors removed and new injector seals fitted.
- Intake manifold removed and cleaned, it was stuffed with black gunge! New intake seals, assuming this is because of bad turbo seals and it filling the intake with oil and mixing with gases from the EGR.
- New maf sensor and boost sensor fitted.
- Found two injectors were never properly coded in. Myself and a friend coded them ourselves.
- Took it to the same company who remapped my mothers C5, they adjusted the current map put on by the previous owner. They were in shock and told me bingo numbers were used in the remap. It was dumping far too much diesel into the engine and used ridiculous amounts of boost. Obviously the previous owner wanted power... I just want fuel economy and reliability
They also found several boost leaks and fixed them, new air dozer fitted.- New Boost solenoid and Vac lines coming out of the solenoid fitted.
- and of course its gotten regular servicing from myself oil, filters for air, oil and fuel, etc...
Engine codes that came up using a cheap OBD reader.
p0238 - Turbocharger Boost Sensor A Circuit High
p0299 - Under boost
p1351 - Glow plug or glow plug relay fault.
Debating buy a Lexia, but this car has swallowed so much time and money that its hard not to drive it into the tide
The engine died on me in the middle of overtaking TWICE! That could have been lethal.
Cleared the codes after replacing the solenoid and lines it was mildly better, drove it hard and no engine light came on. But it just is not boosting right still. Really thought changing the boost solenoid would fix it.
I owned it for a month when the turbo blew. After the new turbo was fitted, I found the drivers sill was non-existent, inner and outer. Plastic side skirts hide some nasty surprises... It had just passed its MOT before I bought and imported it to Ireland. Stevie wonder must have been inspecting cars that day
Had I found it before the new turbo was fitted I'd probably have just cut my losses. Anyways, I'm fairly hands on and welded a new sill in.Only reason I'm still going with it is because I wanted a C2 VTS for years, and settled on the diesel one as I drove 3 hours a day for college. For the money gone into it though, wish I bought a petrol VTS.
I'll test it for boost leaks again in a few days, just waiting on a pipe to fit over the turbo.
Is there anything I could missing missing or have looked over?
Apologies for the huge lump of text, but I've been living with this for months now trying to figure it out and I am close to calling it quits!
As I put the system under pressure (not that it held any), I sprayed the joints in soapy water. 
