Thought I would share some information with you folk. This has been researched over many years, while working on classics and a few sportier cars. Basically it's to do with ever increasing emission laws, and engine performance issues resulting from emission control systems.

I have applied the results to find out what is the best way to give a Fabia VRS engine and various induction components a longer life span.

The emission systems.

The dreaded EGR valve. This is there to mix a small portion of exhaust gasses back into the inlet air. It is used to reduce NOX emissions (Nitrates of Oxygen.) The result is combustion temperatures are reduced, and combustion is more complete due to a slower 'flame front'.

Unfortunately, when EGR is combined with another emission device (Crankcase Ventilation) (CCV for short) you end up with exhaust soot from the EGR valve, combining with CCV gasses which contain oil vapour. Over time, the result is a think tarry like substance which coats the inlet manifold, Turbo, intercooler and boost hoses. This is the primary cause of boost hoses popping off, and variable vane turbo blades sticking. It also greatly reduces the efficiency of the inter-cooler.

So while these systems make the environment a better place, they do cause potential problems for your engine. On petrol cars, removing or modifying these systems, will cause an MOT fail, due to incorrect emission readings during the exhaust sniffer test.

Currently, diesel engines only have a smoke density test during the MOT. Thus, the EGR and CCV systems can be tweaked or even removed.

Obviously the cleanest inlet will be achieved by removing the EGR, and modifying the CCV system. However, the following needs to be taken into consideration.

1: The environment. Any modification should be done with due consideration to the environment.

2: The engine. CCV must still be vented from the crankcase (more later). If you block off CCV, the engine will become an oil fountain, as oil seals blow due to crankcase pressure build up.

Removing the EGR will mean combustion temperatures rise, which can over time cause valve seat burning and piston damage. Removing the EGR valve will also reduce fuel economy, especially at cruise speeds.

Best compromise. If you leave the EGR in place, but remove the CCV gases from the inlet manifold, you get a decent compromise. The soot from the exhaust gas just coats the manifold slightly, and the majority of the soot after the turbo, will simply be blown into the engine during high boost. So the inlet system will remain much cleaner. You can turn down EGR with VAGCOM as well, and further reduce the soot levels.

So what is the best CCV modification? The options are.

1: Vent to atmosphere

2: Vent to Oil Catch Can and then to atmosphere

3: Vent to Oil Catch Can and back into inlet manifold (Still closed loop)

Option 1 is the most efficient, but care has to taken not to allow oil to vent onto the road, and also the fumes must be kept out of the car interior. It's illegal, and a danger to bikers if this method results in oil being dripped onto the road.

Option 2 is again a compromise, but it is the best option. The oil catch can needs to be designed to prevent CCV back pressure. So wire wool 'fillers' that catch the heavier oil, need to be large mesh, and not over compacted into the can. The final vent hose, needs to routed under the car, and further back than the engine firewall, to prevent fumes getting into the car.

Option 3. While this is the most environment friendly option, the catch can will remove the heavier oil deposits, but some oil vapour does get past the catch can, and back into the inlet manifold. So all you are doing, is slowing the gumming up process.

If you remove the EGR but leave the CCV system intact, you remove the soot, but still end up with heavy oil coating the inlet system. If you use stronger boost hose clips, you will stop the boots blowing off under high boost, but the inter-cooler will need cleaned and oil drained out every year or so. Your car will also run hotter combustion temperatures, and will produce NOX in the exhaust gasses.

The proper CCV modification will reduce exhaust smoke, but reduce inlet valve stem lubrication.

Diesels do not use a fuel air mix going past the inlet valves. The fuel is injected directly just before TDC, the intake stroke has only air going past the inlet valve. It is reasonable to assume that over time, slightly increased valve stem wear could result, especially if the EGR has been removed.

Happy modifying.

I went all out on both fronts... aint i naughty :P

I have turned the EGR down with VAG COM. I didnt want to get rid of it for a few reasons.

My CCV system can be seen here.

Originally I vented it to atmospehere but didnt like the idea of nothing between the engine and moisture in the air, so now I have option 2, catch can vented to atmosphere.

I had some teething problems (breather filter blowing oil), but have now sorted this and have been running it for 2,000 miles with no problems.

The only downside is that I need to find someway of routing the outlet pipe downwards or to the back because:

a) when the car is idling and the engine is warm I get wisps off white smoke out from the bonnet over the passenger side headlight haha. Looks funny to passers by, not a lot, but enough to notice.

b)I get a little of oil smell in the car when idling and the engine is cold. I am not sure if this is the decat or the CCV, or both. When driving along even at 5mph there is no smell.

Pics of my CCV system can be seen here.

http://briskoda.net/technical-guides/diy-guide-elephant-hose-ccv-catch-can-mod/111546/8/

smell will most likely be the decat

I've had mine running to atmosphere for around 10k miles now and its all good... Think Devonutopia has had it vented to atmosphere for quite a bit more

I went all out on both fronts... aint i naughty :P

I read the CCV Elephant hose thread, and most of the stuff over on the TDi Forum, so saw your very neat CCV system before, very nice work. My reservations would be the final vent tube being in the engine bay, and the KN style filter on the end of the final vent hose.

Diesel crankcase pressures are pretty high as it is, so if it were me, I would take that final vent hose to beyond the firewall, put a 45 degree slice at the end (prevents freezing), and loose the filter on the end.

If your worried about condensation causing mayo oil in the rocker box, don't worry, the catch can will prevent that.

I have been considering going for option 3, as now I am happy that the filter in the catch can is catching most of the oil coming through.

I know this because my K&N style filter is perfectly clean and has no oily residue inside.

The smoke puffs are a bit annoying too.

MoggyTech - do you think that my current set up could be causing too much back pressure? What are the affects of increased back pressure?

I have been considering going for option 3, as now I am happy that the filter in the catch can is catching most of the oil coming through.

I know this because my K&N style filter is perfectly clean and has no oily residue inside.

The smoke puffs are a bit annoying too.

Might work, but remember you would then be applying manifold vacuum to the return line, so that could reduce the efficiency of the catch can, as vapour 'linger time' is reduced.

Only way to be sure, would be to completely clean the EGR body, then check it again after 10K for any oily gunk.

The VRS CCV setup is a bit weird. The rocker box has a pressure limiting valve in the CCV takeoff point, yet they apply manifold vacuum to it as well. Not quite worked that one out yet. :confused:

I have noticed that on very cold mornings I get lots of white smoke from the exhaust, when the car is warmed up its fine but it was -2.00 a while ago and it smoked for a good 5 minutes at idle one morning whilst I cleaned ice off the windscreen. I have a decat, but could this indicate burning oil?

Joel

I went for option 2 with the CCV and used a compressed air filter in place of the catch can, unfortunately this has a filter element within it which meant I ended up with the filter full of a grotty oil/water emulsion. Also I used some cheap tubing which went brittle in all this cold weather. So I dismantled it cleaned it out and but it back together minus the filter element.

I have an injection pump TDi Octy rather than a PD Fabia and I don't seem to get a massive amount of air coming out of the breather, if you put your hand over the end of the hose you can feel the airflow though. I now have a see through catch can which is rather handy for seeing what is in it. The only problem I had was mounting it, to start with I had it mounted at the back of the engine bu it was higher than the top of the engine and muck built up in the pipe between the engine and catch can. So now I have attached it to the battery holder and the pipe runs down into the bottom of the wing under the battery - I couldn't find anywhere better to mount it and I haven't noticed any smoke/vapour and no smells.

I would take some pictures if I could find the camera.

Just need to clean out the EGR and intercooler now...

Nicely written, thank you. I hadn't considered the (possible) lubrication implication.

I have noticed that on very cold mornings I get lots of white smoke from the exhaust, when the car is warmed up its fine but it was -2.00 a while ago and it smoked for a good 5 minutes at idle one morning whilst I cleaned ice off the windscreen. I have a decat, but could this indicate burning oil?

Joel

White smoke is simply water vapour mate, mine dose it, and it was like that before the CCV mod (Option 2). Might be slightly more with a decat as less back pressure in the exhaust.

Even my 40 year old Moggy Traveller gives out plumes of white smoke on cold mornings. I mean enough to survive a tank battle

I read the CCV Elephant hose thread, and most of the stuff over on the TDi Forum, so saw your very neat CCV system before, very nice work. My reservations would be the final vent tube being in the engine bay, and the KN style filter on the end of the final vent hose.

Diesel crankcase pressures are pretty high as it is, so if it were me, I would take that final vent hose to beyond the firewall, put a 45 degree slice at the end (prevents freezing), and loose the filter on the end.

If your worried about condensation causing mayo oil in the rocker box, don't worry, the catch can will prevent that.

Think you have the wrong person bud... Ive just vented my CCV to air and im running an Allard EGR bypass :confused:

Think you have the wrong person bud... Ive just vented my CCV to air and im running an Allard EGR bypass :confused:

Yes my bad, it was ultra_joel88 in the other thread.

Good write up there ,thanks for that.

Ive had a go at the CCV mod, but need to get better fitting pipes for it so back to standard just now.

EGR delete will be coming along at some point.

1st of all good write up

I have to dissagree with your comment about the fuel economy being reduced, i have noticed no difference at all, i do a regular round trip of 25miles and i have noticed no difference with the EGR being removed.

Sorry mate, but thats my findings anyway, dont know if i'm the only one lol

To combat the temp rise, would using something like a FMIC or water/meth injection system help?

Once again, good info

1st of all good write up

I have to dissagree with your comment about the fuel economy being reduced, i have noticed no difference at all, i do a regular round trip of 25miles and i have noticed no difference with the EGR being removed.

Sorry mate, but thats my findings anyway, dont know if i'm the only one lol

To combat the temp rise, would using something like a FMIC or water/meth injection system help?

Once again, good info

MPG drop is only likely at steady cruise speed, as that's when the EGR mostly gets opened. Any drop is likely to be very small though.

WRT temp rise, yes a front mounted IC would help a great deal. Water/Methanol is a bit outside of my current knowledge, but I know that NOS systems send the temps way up. I would think anything that increases combustion energy, and thus heat, wouldn't be much good at cooling.

Ah more research needed, I'm happy

Removed my CCV bypass system Friday to put it back to standard for a day as I was going to clean it out Sunday.

My MPG has gone up markedly (48mpg to 56mpg on the same journey I make every week).

The car also seems to be running a lot more smoothly.

Any ideas?

I am thinking of doing the bypass but returning it to intake rather than atmos as it seems to run bettter like this.

Removed my CCV bypass system Friday to put it back to standard for a day as I was going to clean it out Sunday.

My MPG has gone up markedly (48mpg to 56mpg on the same journey I make every week).

The car also seems to be running a lot more smoothly.

Any ideas?

I am thinking of doing the bypass but returning it to intake rather than atmos as it seems to run bettter like this.

Very strange, you should get better MPG with the CCV vented to atmosphere.

Things to check, no air leak at blanked off CCV connection on inlet manifold

No excessive back pressure caused by oil catch tank or filter.

I'll be watching this thread closely as i'm very interested in any finds

Very strange, you should get better MPG with the CCV vented to atmosphere.

Things to check, no air leak at blanked off CCV connection on inlet manifold

No excessive back pressure caused by oil catch tank or filter.

How would one check the back pressure?

How would one check the back pressure?

You need to tap into the CCV out hose, and use an airflow meter. Quite hard to find such a tool these days though. If you can borrow one, you connect it to a short hose direct to the CCV pipe on the rocker cover and take a reading. Then connect up the CCV bypass with the air flow meter at the end of the bypass run. There will be a slight decrease in the flow due to oil catch can, but the readings should be very close.

Here's a link to an article with an air flow meter in use.

http://www.guzzle7pt3.com/ccv1.html