CALLING ALL DS3 OWNERS WITH THE THP ENGINE !!!....Who's had new engines ??

[cyclone]

Yes, I'm no expert on this stuff but just can't see them redesigning it if there wasn't a problem.

[Czar]

Yes, I'm no expert on this stuff but just can't see them redesigning it if there wasn't a problem.

Lucky for me and you I am an expert, this referred to image of the intake manifold with this particular PCV distribution arrangement is to cure an issue for extreme cold climates, the original position of the PCV intake on the intake manifold, suffered from water droplet formation in the PCV tube (pictured in my image) and in the plenum, in extreme cold climates, and so a different approach for extreme cold climates had to be developed, and this is what they came up with, also this is where the blanking plug cap comes from!

So unless you live in an extreme cold country, you won't and shouldn't have this intake manifold fitted to your engine.

[cyclone]

Glad to have a expert on these engines with the problems can use one. But the blanking plugs are standard on RCZ pugs here in Germany is that not the case in the UK.

[Czar]

Glad to have a expert on these engines with the problems can use one. But the blanking plugs are standard on RCZ pugs here in Germany is that not the case in the UK.

Yes the blanking off caps, are used world wide on the newer THP engines which utilise the double vanos timing units on the camshafts, as they have internal PCV passages in the cylinder head ports for each individual runner, as they only have the 1 external PCV line, which is fed into the air intake pre turbo.

[cyclone]

OK so now I'm tracking. Back to our manifold, What would happen if liquid oil not vapour were to enter the manifold thru the single port?

[Czar]

OK so now I'm tracking. Back to our manifold, What would happen if liquid oil not vapour were to enter the manifold thru the single port?

There shouldn't be any liquid oil enter the inlet manifold, any oil that does coat the inside of the inlet manifold, intake tract runners in the cylinder head and the backs of the inlet valves, only does so, because as the crankcase oil mist vapour contains suspended oil particles, (and for emission purpose legislation, is fed into the inlet manifold to be burn't in the combustion cylinders) some oil will fall out of suspension dependant on piston mean speed (air flow velocity) that said, any oil either air suspended or otherwise, plays a role in upsetting the delicate air/fuel charge mix, and can attribute to pre detonation knocking, pinking for the old school among us, and subsequently can lead to piston destruction, and often does.

Now before any of you, think, ah this is a design flaw or fault of PSA, think again, all manufacturers have very strict guide lines regarding emission control, and in order to comply, the crankcase oil mist vapour must be returned to the combustion cylinders, this unfortunate cycle, happens to all GDI (gasoline direct injection) engines, with the exception of Toyota/Lexus who have introduced a secondary injector/s to wash the backs of the inlet valves, (regular port injection) whilst still utilising GDI technology, so a step backwards, to go forwards!

[cyclone]

Thats just the thing Czar, I did cap off the back PVC port and when I pulled the line out it did not have a film of oil(which wouldn't have overly concerned me) but accumulation of liquid oil that was puddling in the groves of the line.

[Czar]

Thats just the thing Czar, I did cap off the back PVC port and when I pulled the line out it did not have a film of oil(which wouldn't have overly concerned me) but accumulation of liquid oil that was puddling in the groves of the line.

The small amount of oil trapped within the ridged grooved lines of the PCV feed line, is exactly what you would expect to see, the ridged grooves are dong their job, disturbing the air flow enough to encourage oil particles to fall out of suspension, nothing to worry about.

[cyclone]

Thought the point was to keep it suspended so it could be burned evenly????

I know I'm being annoying but.....trying to fully understand

[Czar]

Thought the point was to keep it suspended so it could be burned evenly????

I know I'm being annoying but.....trying to fully understand

You and (the manufacturers) want as much suspended oil within the crankcase vapour to fall out of suspension before any of it gets to the backs of the inlet valves, as the manufacturers were and are aware that GDI engines would and will suffer from excessive carbon deposit build up on the backs of the inlet valves, so in order to do this as cheaply and as maintenance free as possible, they implement simple ideas, it certainly isn't the best idea by a long shot, that said they have economical cost restraints, and service profits to consider too!

So what you see/saw in your PCV line is a good outcome, it means that the manufacturers simple ideas are helping combat the ever increasing problem.

[cyclone]

But the only place for that oil in the line to go when enough builds up is into the manifold in liquid form.

[Czar]

But the only place for that oil in the line to go when enough builds up is into the manifold in liquid form.

Wrong, over time, it simply gets lifted back into suspension, however, because the settled oil is heavier than air, it takes a long time for it to be lifted back into suspension, and any that does become resuspended into the air stream, is dependant on velocity to stay suspended, and so some will inevitably fall out of suspension again when changing direction 90º at the bottom of the inlet manifold (plenum) and pool in the void there too, this is a never ending cycle.

[cyclone]

Going to have to think about that for a while. You obviously know what your talking about but that was a lot of oil in that line for 700ish miles just cant picture it after 15k. Not that I do not believe it, seems to make engineering sense, but that doesn't always work out in real life.

Good stuff can tell you will be an asset around here

[Dave Clarke]

Good job the thp engines don't suffer from excess oil deposits carbonising on the inlet valves then

[Czar]

Good job the thp engines don't suffer from excess oil deposits carbonising on the inlet valves then

I guess you've not read my posts correctly, all THP engines and all GDI engines with the exception of Toyota/Lexus suffer from excessive carbonising on the inlet valves!