Nearside Rocker Breather/intake - does this look right??
Discussion
I know the car is going in soon but I'm still plugging away at it. one thing I hadn't looked at was the nearside rocker breather which, if I understand correctly, let's air in that gets drawn from the offside breather into the plenum.
Mine doesn't appear to have any form of breathing to it whatsoever! Is this right? The centre "core rod" was right at the top but I used one of those sonic scrubers and some WD40 and it's now dropped tio where it currently sits. It appears to be air tight - well it's certainly WD40 tight as if I fill up the dip it doesn't drain away so it can't be acting as a breather can it? I'm assuming it should be just an open tube which might help explain why I'm struggling to lean off my idle mixture...
I've googled around and can't find any thing to tell me what it ashould look like.
Mine doesn't appear to have any form of breathing to it whatsoever! Is this right? The centre "core rod" was right at the top but I used one of those sonic scrubers and some WD40 and it's now dropped tio where it currently sits. It appears to be air tight - well it's certainly WD40 tight as if I fill up the dip it doesn't drain away so it can't be acting as a breather can it? I'm assuming it should be just an open tube which might help explain why I'm struggling to lean off my idle mixture...
I've googled around and can't find any thing to tell me what it ashould look like.
Edited by smash on Sunday 8th June 18:14
Yes that is right - the little hole should allow air in but its only tiny. Clean it out with a pin (and don't drop it in!) Then there's a little sponge filter trapped on top with a plastic clip-on cap. If you've lost that just tie-wrap a thin sponge over the top for now (sorry to advise a bodge Woolie!!! ;^)
That is strange yes it appears to be closed:
Perhaps you can drill it out but you'll need a fine drill bit and you must use a drill press or it will snap in the hole. You can get 0,8mm drill bits for electronics.
I don't think it will cause bad running in itself because you can easily compensate using the bypass on the AFM for idle CO.
Perhaps you can drill it out but you'll need a fine drill bit and you must use a drill press or it will snap in the hole. You can get 0,8mm drill bits for electronics.
I don't think it will cause bad running in itself because you can easily compensate using the bypass on the AFM for idle CO.
Edited by adam quantrill on Sunday 8th June 21:10
Well that's just the problem - I don't have enough adjustment on the AFM - best I could get was 0.8 lambda.
Interestingly the TP was set to 0 volts at idle when I started fault finding - an attempt at getting the idle mixture leaner?
(the 0.8 Lambda is after I set TP as per HonestJohns guidance)
Interestingly the TP was set to 0 volts at idle when I started fault finding - an attempt at getting the idle mixture leaner?
(the 0.8 Lambda is after I set TP as per HonestJohns guidance)
So that would be about 5% CO?
Yes that seems a tad high but I don't think the pinhole will solve this it's too small.
I had a similar problem on my 350i which I worked around by trapping a small pipe between the AFM outlet and the hose. The pipe was an 8mm copper pipe squashed a bit flat to squeeze in, and let in enough air to reduce the CO from about 5% to about 2%, then I used the adjuster to fine-tune it for the MOT.
So that gives you an idea - about 6-8 square mm will admit enough air to make a difference - the pinhole will be negligible.
Yes that seems a tad high but I don't think the pinhole will solve this it's too small.
I had a similar problem on my 350i which I worked around by trapping a small pipe between the AFM outlet and the hose. The pipe was an 8mm copper pipe squashed a bit flat to squeeze in, and let in enough air to reduce the CO from about 5% to about 2%, then I used the adjuster to fine-tune it for the MOT.
So that gives you an idea - about 6-8 square mm will admit enough air to make a difference - the pinhole will be negligible.
smash said:
one thing I hadn't looked at was the nearside rocker breather which, if I understand correctly, let's air in that gets drawn from the offside breather into the plenum.
Mine doesn't appear to have any form of breathing to it whatsoever! Is this right? The centre "core rod" was right at the top but I used one of those sonic scrubbers and some WD40 and it's now dropped to where it currently sits. It appears to be air tight - well it's certainly WD40 tight as if I fill up the dip it doesn't drain away so it can't be acting as a breather can it? I'm assuming it should be just an open tube which might help explain why I'm struggling to lean off my idle mixture...
I've googled around and can't find any thing to tell me what it should look like.
I've done a mash-up of stuff I created for other O.P.'s looking for similar answers.Mine doesn't appear to have any form of breathing to it whatsoever! Is this right? The centre "core rod" was right at the top but I used one of those sonic scrubbers and some WD40 and it's now dropped to where it currently sits. It appears to be air tight - well it's certainly WD40 tight as if I fill up the dip it doesn't drain away so it can't be acting as a breather can it? I'm assuming it should be just an open tube which might help explain why I'm struggling to lean off my idle mixture...
I've googled around and can't find any thing to tell me what it should look like.
'for mash, get smash'
The inlet manifold steel gasket must not leak so check the rubber end seals and along the gasket edges with your easi start.
Also the rocker cover gaskets must be fully sealed.
There is an easy way to analyse Rocker Cover Gasket integrity.
- On a completely NON-leaking Efi system if you remove the oil filler cap, the smooth idling engine note will become noticeably unstable.
- The engine RPM also (usually) drops.
- The reason for this is obvious - Rogue air is able to enter the crankcase ventilation system and upset the Efi equilibruium.
- If an engine ALREADY has a rogue air leak via the rocker gaskets AND exhibits an unstable idling speed as a result, then removing the oil filler cap has little or no effect on the unstable idling situation.
- Alternatively if the Rocker cover gaskets are OK but idling is already unstable for a different reason, removing the oil filler cap will have worsening effect, by adding rogue air into the ventilation system further affecting the already unstable idle speed.
However, the above depends upon a fully operational crankcase ventilation system which itself is also key to having a to having a stable idle speed.
Blockage anywhere from the 0.040" hole in the rocker cover mushroom filter though to the flame trap, vent pipe and plenum breather gallery will negate the action of the ventilation system as would the wrong sized hole or air leaks in the pipe, etc.
And of course the whole ventilation system is subject to the vacuum inside the inlet tunnel at idle, constantly sucking up foul gasses from the crankcase.
Under normal driving the vacuum pretty much disappears, but any pressure inside the crankcase sends the gasses up the same route anyway.
Note: You can see from studying the diagram how TOO MUCH air coming thro' the ventilation system or any part of it being open to atmosphere (breached gaskets, as mentioned) may upset the Air Fuel ratio, beyond the ability of the AFM and ECU to apply correction.
Errors and Omissions gratefully received!
Sorry, should have said I already understand the crankcase ventilation system from description at www.roversd1.info and I do currently have a stable idle. I was just trying to figure out if there's any reason why I can't adjust the AFM to more than 0.8 lambda which is too rich at idle which is why I checked that breather.
To mash up your answer Honestjohn in terms of what I asked then, basically, it should have 0.04" inch hole. This bit is helpful as I can drill it out now - thanks
To mash up your answer Honestjohn in terms of what I asked then, basically, it should have 0.04" inch hole. This bit is helpful as I can drill it out now - thanks
Edited by smash on Monday 9th June 09:01
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