Has the time finally come for a DS3 Racing engine rebuild??

[xantia_v6]

So I did a compression test today.. I got about 185psi or just shy of 13bar across all the cylinders.. seems a bit high heh??

I would put the brakes on here, just a little.

I think that it is more probable that your compression gauge is inaccurate than all cylinders have an abnormally high compression pressure.

If your compression pressure was really too high, then the engine ECU would be throwing knock and super-knock fault codes all the time.

I am not aware that these engines have any history of carbon build-up in the cylinders themselves, just in the inlet ports, which is a different set of symptoms.

I think that all of the symptoms that you initially listed could be caused by a failed PCV valve, or perhaps by bad turbo seals allowing an abnormal quantity of oil into the engine.

[notrix]

I would like to try and diagnose the PCV system. I have the OEM PCV blanking caps lying around (OEM part #0361.S4). Do you think installing these would help me diagnose a faulty PCV valve? The caps are for blanking off the rear PCV connection between the rocker cover and the intake manifold.

[xantia_v6]

Yes, fitting those caps blocks off the rear PCV valve (the one that I suspect has failed), and with that blocked off, it does not matter if the front PCV is leaking, as there is no source of suction to suck excessive fumes from the crank-case. In fact on my car (which has a good vapour separator fitted), I have left the front PCV valve open, so prevent the slight pressurisation of the crankcase that can encourage oil leaks.

With the rear PCV blocked off, any blow-by past the piston rings will come out the front breather and be easy to detect (there will normally be some, but not an excessive amount at idle.

[notrix]

Ok.. I'm a bit worried about possibly increasing the cranckcase pressure if I fit the caps but I guess for testing purposes it should be ok. I'm gonna install the catch cans I have soon but I need to figure out if the rear PCV system has failed anyways so..

[xantia_v6]

Any positive pressure in the crankcase is vented via the front pcv valve to the turbo input, as it always was when the engine is on boost.
For test purposes I would leave the front pcv hose disconnected so that you can see how much vapour is ejected.

[notrix]

Allright.. Cheers. I'll try that

[notrix]

I just installed the rear PCV blanking caps. No difference regarding the rough idle. I filmed a short video of the front PCV hose after blanking off the rear one. Of course I forgot to check how it was before

Here's the clip;


If you're on a computer sorry for the aspect ratio

[Nemo26]

I've seen high pressure fuel pumps failures in the way that the fuel leaks through them in oil line. Remove crankcase pipe and block the hole to engine temporary and check fuel trims before and after. You'll see improvement. Fuel evaporetes from oil sump and creates rich condition, there is basicly one more fuel source and that is fuel vapour from oil sump which goes trough crankcase breather pipe in intake manifold. Ecu tries to compensate and cuts flow trough injectors (rough idle).

[notrix]

I've seen high pressure fuel pumps failures in the way that the fuel leaks through them in oil line. Remove crankcase pipe and block the hole to engine temporary and check fuel trims before and after. You'll see improvement. Fuel evaporetes from oil sump and creates rich condition, there is basicly one more fuel source and that is fuel vapour from oil sump which goes trough crankcase breather pipe in intake manifold. Ecu tries to compensate and cuts flow trough injectors (rough idle).

Thanks for the tip. Do you mean that fuel could leak from the pump internally in the engine block?

[Nemo26]

Yes, hp pump is lubricated with engine oil.

[notrix]

Yes, hp pump is lubricated with engine oil.

Sorry for the delay.. The car is stowed away for winter storage so progress with trying to diagnose the problem is currently slow

I've done some more research into the high pressure fuel pump and it seems the only way it could leak fuel into the oil would be through it's connection to the camshaft. I have read about several cases where the HPFP has failed on these cars but can't seem to find any cases where it has leaked fuel into the oil. Today I checked the fuel rail pressure and it seems normal both on idle and at a steady 4000rpm. Given the amount of problems with the original version of these pumps I'm tempted to replace it anyway but I'm suspecting the real problem lies somewhere else..

[citroenguy]

I'd say you need to get the valves blasted ocr cleaned, i suspect the rough idle is because of carbon buildup whitch is common on these.
And also get the latest crank case ventilation/vevhusventilation parts .
You never know but i doubt there will be any piston/ring damage at this low of a mileage, and this engine isn't known for that either.

[notrix]

I'd say you need to get the valves blasted ocr cleaned, i suspect the rough idle is because of carbon buildup whitch is common on these.
And also get the latest crank case ventilation/vevhusventilation parts .
You never know but i doubt there will be any piston/ring damage at this low of a mileage, and this engine isn't known for that either.

Totally agree.. what has me dumbfounded though is why such amount of gas seemingly ends up in the oil pan..

[Sharkie]

Lots of cold starts, bad spray pattern or just regular use. Or overfueling the engine.
Some fuel in oil is normal.

[notrix]

So I finally got around to walnut blast the intake valves but it did nothing in regard to the rough idle.

Before;


After;


I also installed a dual oil catch can for the PCV system and replaced all the coils and spark plugs.. still no difference.

I don't drive the car much in general and it usually sits for about 5-6 months during the winter so I'm maybe thinking the injectors could be clogged. Other possible issues I can think of maybe bad HPFP or bad timing due to stretched timing chain or faulty tensioner.

Anyone have any ideas what to check next?