This is in the same area to the problem that's been doing my head in on my car. The very valid question Smaky has asked is about how much oil your car is burning.
The pipe you have pictured just has a coupler, the valve is integral to where the idle breather joins the inlet manifold vertically rather than horizontally just off the left hand edge of the second photo.
From what I've worked out as soon as the engine is running at tickover the inlet manifold vacuum pulls the plunger in the idle breather valve down compressing the spring allowing crankcase fumes in after the throttle. Once the car is revving higher and moving there is higher negative pressure at the air inlet end of the pipe you have pictured and therefore the crankcase fumes are drawn through that pipe rather than the valved one.
It appears it is done this way because after a certain engine speed there are now such a higher volume of fumes (and remember these fumes are full of carbon particles, virtually oxygen free and warm so they are almost pure power robbing smog) that it is necessary to draw them in before the throttle body so that via the Lambda probe the ECU can adjust the mixture to account for the fumes.
This is further complicated by the petrol fume system also venting into the inlet manifold which cuts in and out controlled via a pressure sensitive valve arrangement and the Lambda sensor which when activated sends a message to the ECU to lean off the injectors accordingly. (if it doesn't do this accurately then RPM wavers)
This is where I need further help as by looking at all the ECU info I can get hold of I can't work out just what proportion of smog the system is designed to accept without taking further measures. The handbook indicates that it should cope with quite a high volume as it states these engines are designed to use 1 litre of oil per 1000KMs!
It appears from the schematics that at very high smog intake levels the ECU may actually activate the Idle Stepper Motor (hence rising RPM and slow falling to tickover) to allow enough air in to get a clean burn with no misfiring.
The ECUs definitley seem to learn over a period of time how much smog in the mixture to allow for. On engines where the ECU can't activate the ISM (slipping gears or ISM not calbrated correctly into ECU) to increase cool air input for a clean burn then a heavy breathing engine might have such a low percentage of oxygen at low to mid RPM that there is quite a bit of unburnt fuel left after the firing stroke or slightly delayed full burning hence wobbling RPM and "knocking".
Even without further help it is obvious from what I've worked out the importance of a bang on Lambda sensor and for cars with exceptionally heavy crank case breathing that oily smog would coat the Lambda and send the probe out of calibration fairly quickly-hence the eating lambdas problem.
From what I can see the air correction via ISM is triggered in a similar area to the one that increases RPM for air con load but I really need someone with a working knowledge and experience of the Bosch 1,5,5 system to help as I've hit the limit of where the theory stuff I did years ago at technical college hits the wall of specific knowledge.
I had planned to just use a twin input oil seperator / vented catch tank to take the engine smog away from the injection system to get rid of the associated problems plus have a more responsive and economical engine. What Andy has done is a very simplified half version of that but could mean an MOT failure plus the filter will saturate fairly often and dribble oil into the bay.
However when I removed all of the crankcase breathers from the injection system my engine wouldn't run properly so the ECU obviously can't cope with suddenly having none of the smog it has learnt to expect to cope with. When I removed all the smog equipment off my Fiero V6 (a 200BHP engine reduced to 140 by it) I had to order an ADS STRIP chip for the ECU but can the re-programmable ECU on the plastic topped engines be "told" to run the engine properly with no smog?
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