Hi Lenroc,
I too have the 1.6Vti engine in my 2008 207SW. All the vacuum observations you have made tally with what I've found with mine.

Yes, there is a vacuum formed in the crankcase and it is surprisingly strong. The PCV valve in the rocker cover is designed to regulate the amount of vacuum so that as the revs climb higher the engine doesn't suck too hard on itself!

The oil breathing is a 'closed' system and indeed RELIES on that vacuum being formed. The removal of the oil filler cap with the engine idling will suddenly confuse the ECU as it will instantly affect the mixture and the computer will try to compensate and this can sometimes make the revs climb. Replacing the filler cap will also suddenly confuse the ECU in the other direction so a stall may also occur.

So once you appreciate the nature of the closed system and how the ECU calculates its mixture and emission figures assuming that the crankcase vacuum is there, you can then appreciate how suddenly removing or reinstating that vacuum with the filler cap can affect the engine's running.

In trying to explain your high hydrocarbon test failure it could be a defective PCV valve. It's a rubber membrane that can either leak round the edges or have an actual split in it. Either kind of leak would upset the mixture without necessarily loosing the vacuum.

 

Thank you

After reading your replay, I start to think that the PCV valve is indeed working as it should.
I am about to perform a compression test so I can rule out the piston rings(although I do not have much pressure inside the engine, if anything I have negative pressure since the PCV connected hose is sucking out a fair amount)

On further diagnostic I performed since since my last post, I read the engine parameters when running at idle the oil pressure came out as "overpressure"

so it seems that there is pressure building out somewhere in the engine.

Is there any other breather of some sort? or is the PCV valve in the crankcase the only way out of the engine?

I still have the white smoke out of the engine, and no error code, no MIL light and no clear lead on what can cause this. The engine is running fine, no issue what so ever, no knocks, no strange sounds, no hesitations, no erratic idle, all cylinders fire as they should (i disconnected in turns each spark plug and they definitely work as the should)

It has to be something, I am missing, but honestly, apart from the compression test I cannot think of anything else (i will perform that once my friend will bring his reading tool)

I will keep you in the loop, whatever happens; Thank you very much for reading

 

There could be a multitude of reasons for high HC. If there are no codes logged look at live data for injector correction, coolant temp, intake air temp and calculated air mass etc.

Can you get a copy of the original emission fail or retested as the CO and Lambda values can help fault finding. I assume the car was fully warmed up prior to the test, with an italian tune up prior to test it can take a while to light off the cat on some VTI's my daughters old 207 was

 

About the emission test: I bought this car, the seller advertised as "good working order but not used, expired MOT"; the guy looked genuine so I trusted him, it was my fault that I did not check MOT history before;
Once I checked on-line all I can see it is the failure due to high HC. I will eventually take it to another test, but I want to try all I can before I will get another failure.
I have no idea if the car was properly hot when they did the test. It looks like a car that has not been drive a lot, and looks like most of the mileage ware from trips of 3-4 miles. so an Italian tune up will probably help, except that I cannot legally drive the car.
My local MOT is less than 1 mile from me so I will book an appointment to have it tested again soon.
I will keep you updated about the values I will get from that;
prior to the test I will try to keep the car running on high revs for as long as I can so it might act like a proper run down the motorway

 

As for the white smoke, are you getting through coolant? if not have you bled the system fully.
It will chuck out white/grey smoke if air is trapped around the sensor as it will overfuel, it looks like HG fail from the tailpipe but its not.

 

I had a suspicion that there is something in the coolant circuit.
once I got the car it was low on coolant (well below the min)
I topped that up right away, but not bled it properly, just top up to the max mark.
Anther reason for suspecting coolant problems is that I recently had some strange fan behaviour, i.e fun runs on fast as soon as you start the engine cold and in cold weather
I am not sure if it uses coolant, there is no indication of that since it stays stable (since I topped that up it stay at the same level)
there is also no excessive pressure or any bubble on the coolant bottle (except for the normal pressure)

Do you know how to bleed the coolant system properly?
I will bleed that and see what is next
Also another silly question: I cannot take any of the spark plugs out, all my spark plug tools are too big for the job; I tried with a small socket (14 mm long type) but it is too short for the job, is there a special tool or socket I can use?
thank you

 

the way I bleed it, engine hot and running and rubber gloves, you will find a valve that looks like a tyre cap behind/left of the battery on bulkhead, release it until you see coolant, screw it back up and squeeze pipes hard and fast, repeat, repeat each time releasing valve. can take a few miles for the ecu to adjust.

spark plugs, magnetic best Peugeot Spark Plug Socket 14mm 12 Point Thin Wall 3/8

 

HI
I properly bled the coolant, it is coming all clear. I did a compression test on all pistons and I have about the same pressure on all of them, about 12 bar on 11.8 to 12.2 bar
so a healthy compression.
the spark plugs were black and wet, which indicates rich mixture, or oil burning.
the white smoke is still there, the ECU does not have any codes, no light on the dash.
I have to also do a leak test ( to see if the pressure in the pistons is stable) but apart from that I cannot think of anything else
Except of a faulty ECU, do you know if ECU can be changed on its own (or it needs the kit - usually with dashboard, key, etc)

 

You need to see live data readings not just look for codes.

live data tells you what IS happening codes tell you what HAS happened.

Sounds to me the engine is healthy and an italian tune up is all it needs !

Book it for an MOT and go for the longest fastest roads you can on the way there you dont have to go directly

 

RE: took out the intake manifold

Hi
I will take to a test, but before that I want to clean and inspect all the systems (air intake, fuel intake, o2 sensors)
today I just took out the intake manifold, the throttle body and the injectors.
I can see some oil and dirt inside the throttle body which I will clean. However I've seen that the rocker cover breather, it is going inside the manifold and it has like a sensor just before the manifold, that sensor has a wire that goes no where (it was not attached to anything and I cannot see any loose wire in there)
the breather hose is just a plastic tube that goes from the rocker cover into the manifold (sorry I cannot attach pictures) at the manifold end there some sort of sensor with a 2 wire plug)
Interestingly enough, when I search for peugeot 1.6vti breather on-line, I can see a hose that looks nothing like the one I have
I can see one like mine on some Citroen 1.6 vti
Not sure if you know what is there attached to this breather

also, do you know if there is a fuel pressure regulator, all I can see is a hose bringing fuel inside the injector rail, but not sure where the return line is nor I can see a pressure regulator

Thank you

 

RE: took out the intake manifold

Hi
I will take to a test, but before that I want to clean and inspect all the systems (air intake, fuel intake, o2 sensors)
today I just took out the intake manifold, the throttle body and the injectors.
I can see some oil and dirt inside the throttle body which I will clean. However I've seen that the rocker cover breather, it is going inside the manifold and it has like a sensor just before the manifold, that sensor has a wire that goes no where (it was not attached to anything and I cannot see any loose wire in there)
the breather hose is just a plastic tube that goes from the rocker cover into the manifold (sorry I cannot attach pictures) at the manifold end there some sort of sensor with a 2 wire plug)
Interestingly enough, when I search for peugeot 1.6vti breather on-line, I can see a hose that looks nothing like the one I have
I can see one like mine on some Citroen 1.6 vti
Not sure if you know what is there attached to this breather

also, do you know if there is a fuel pressure regulator, all I can see is a hose bringing fuel inside the injector rail, but not sure where the return line is nor I can see a pressure regulator

Thank you

Hi Lenroc, did you find what was causing this issue? I suspect I have similar, as it looks like I have a vacuum leak at idle which causes the engine to run rough. Thanks in advance!

 

lenrock did you solve the problem with your 1.6 vti

 

i have the same isue,,and no clue what hapening, i try ewrything nothing work

 

I am going to do my PCV this week anyway - a complete kit for it is only £20 (don't just get the membrane, get the whole kit). It's an easy fix to do in half hour that rules it out. I get occasional whit smoke from exhaust particularly if I've been driving then suddenly hit and pull away in traffic. Apart from the "usual" quart of oil on the 1.6vti prince engine I go through I'm hoping this may remedy the issue before looking for more expensive fixes.