help me understand EGR situation

[Yilld]

So, I was reading into the whole EGR situation. There are loads of different opinions and most stuff is about diesel engines.. So correct me if I am wrong, but this is my conclusion:
EGR in our turbo petrol cars reduces the exhaust temperature during part throttle by richen the mixture, therefore less stress ond EX valves and turbo. Blocking / removing the EGR, the ECU measures lambda and corrects for the missing EGR by injecting more fuel. This would result in less mgp, same exhaust temperature but less gunk in the intake? Am I right?
Is there an "EGR active" map in versatuner? Should I correct a tune for a blocked / removed EGR?

Thanks

[mituc]

The main function of the EGR is to reduce emissions. The system is pretty much like this:
1. under low load relatively inert gasses are recirculated from the exhaust back to the intake;
2. the cylinders are filled up to a certain percent with this gas, the rest is air/fuel mixture;
3. when the air/fuel mixture burns it produces heat which will make all the gas in the combustion chamber expand and push down the piston. That includes the relatively inert gasses recirculated from the exhaust;
4. even though it's relatively inert (and I'll explain later why I say relatively and not totally inert) the gasses that came from the exhaust also heat up and produce mechanical work which help generating the pressure (which given the piston surface translates into mechanical force) that pushes the piston down.
5. during the exhaust cycle the monoxides from the recirculated exhaust gasses previously introduced into the combustion process oxidize even more and that basically make the number or molecules decrease by combining them into larger molecules (some of the NO becomes NO2, some of the CO becomes CO2, and so happens with larger molecules or organic radicals which later become soot). In this stage the decrease of number of MOLs of gas makes the pressure drop a bit which results in that cooling effect they talk about.
6. the resulted gasses WHEN using an EGR system are used by 3-way catalythic converters systems (usually 2 cats) to further lower the pollutants (basically produce more NO2, CO2 and water. When not having an EGR system this process is not fully complete, even though it happens.
7. the cooling effect has absolutely no benefit on the longevity of the internals (pistons, piston rings, cylinder walls, valves, exhaust valve o-rings). Because it doesn't happen during thermicaly stressful situations such as low/mid RPM fast spool or partial-WOT/WOT situations.

However, keep in mind the following:
1. on our cars EGR works only under low load and only then the commanded AFRs are stoichiometric. This means that theoretically all the petol injected could burn cleanly using all the oxygen that came in with the air aspirated by the engine. The newer cars have more advanced EGR systems, and currently probably the neatest EGR system is implemented also into a Mazda, the SkyactivX series, which have continuous EGR, and the gasses are recirculated AFTER they pass through the catalythic converter.
2. The heat reduction when the burn is stoich can also be implemented by slightly increasing the timing advance, as long as the gas used allows it. And it usually does, quite a bunch, but the price for this is an increase in nitrogen monoxide and other nitrogen oxides (NO/NOx).
3. because the inert gasses from the exhaust are not there any more when you block the EGR, that volume needs to be filled with air and fuel. Because of that you will notice an increase in fuel consumption during normal driving/cruising. Remember the EGR valve is shut off during mild/hard acceleration, it is open only at idle and during closed loop/stoich burning situations).
4. the main downside of using EGR with DI engines that do not also have PI is the fact that everything in the intake gets contaminated with exhaust soot. If the engine also has weak compression and/or the turbo is using some oil the accumulation of soot is horrendous and fast.

What I did:
1. kept the EGR (which means that I also had to keep the factory intake and exhaust manifolds);
2. added two better flowing catalythic converters
3. added WMI;
= result: the quickest and most powerful 3MPS/MS3 that is emissions compliant (60-100mpg in 3.62s). And no, it's not because I excel at anything, it's just because everybody else wasn't stupid enough to mix high power with emissions compliance while I was stubborn at doing it.
I'm thinking that next I may look into extracting exhaust gasses after the 1st cat and do a semi-continuous EGR based on the pressure differential between intake and exhaust, and not close the EGR up until load 1-1.2 or until the pressure from the exhaust is greater than the pressure form the intake (which with double-catted exhaust happens pretty soon).

I'm not recommending or telling you what to do, I'm just saying that if your concern is only minimizing the sooty mess in the intake you can always add port-injection (WMI is the quickest and most reliable way with great effects) and produce a lot more power safely and also truly protect the engine internals if you don't have a built motor yet (or even if you have). Personally I'm on a quest to show people that we can still meet emissions and produce big power, and I'm doing that with both my 2.3DISI-fTw cars.

Also, if you blocked or deleted the EGR when you flash your tune make sure you check the Deleted EGR option from the tune advanced options.
So I hope now all the aspects are clear

[Yilld]

Thank you for this nice explanation!
MPG is not really a concern for me (otherwise I would not drive a MPS). The things I want is no soot in my intake and not damaging any part of the engine.

Is the EGR control accessible in Versatune?

[mituc]

Is the EGR control accessible in Versatune?

No.