All engines have EGR.
It's used to reduce peak combustion temperatures to reduce NOx emissions.

It slightly reduces combustion efficiency, but you can't get to emissions targets without it.
The biggest issue with it is the hot gases introduced into the inlet manifold that aids carbon build up when coupled with PCV.

Not the case my friend ....

There is a lot of petrols that do not have egr , loads of Vauxhall models do not have it , many of the new generation Audi’s and bmw petrols do not have egr , Fiats multi air petrol engine do not have egr

The Vw 888 petrol engine does not have external egr control , with new combustion chamber design and individual control of valve lift and adjustable opening and closing of valve timing the engine can dial in late exhaust opening which leaves an amount of burnt gases in the cylinder helping lower burn temps to keep nox down .
Many manufacturers have come away from egr and are using selective catalyst reduction , extra nox cats and add blue systems , this 888 engine also had common rail direct into cylinder injectors ,and injectors in the manifold ..... there is no exhaust manifold , the turbo bolts straight onto the head , it has no water pump .........

I’m going off on a tangent here , back to the plot , looking at the self study literature on the v10 fsi engine it does not have egr so it probably does it’s nox reduction through valve timing control , and like you correctly said,mixing hot gases with relatively cool inlet gases with crankcase mist is a great carbon maker that can add to the Black Death process , in the v10s case just the mixing of pcv in the manifold is sufficient to cause the Black Death and the lack of manifold injectors to ‘ wash ‘ the back of the valves it’s hard to escape from the build up .

On some of the 4 cyl fsi engines they do have egrs ,and a mod you can do (if you have a ecm file writer )is to switch egr off or ‘ calm down ‘ the egr duty cycle to slow back of valve build up .

Anyhow enough of engines ....happy new year everyone 👍

Well I didn't know that!
Late valve opening or early closing is such a better way to control NOx than EGR, but would require some really precise valve timing, particularly high in the rev range.

The EA888 engine purportedly has the port injectors precisely as a carbon reduction technique. It's heresay, but there is no efficiency to be gained by port injection over direct injection.

Thanks for teaching me something after I've opened my big mouth 🤐 🤔 🎓

The valve timing EGR is called Internal EGR :) And yes, our cars have that. Good thing is, this can be either disabled or tuned out, still working on that. Will share my findings and solutions.

It is indeed partial cause for the carbon cake, combined with the passive pcv which needs deletion too. Working on a kit for that as well.

Always learning 27 ....I go on quite a few courses with work so get to see some of the new technologies before it’s generally released...thing is ,as I’m getting older all the new stuff I learn some of the old stuff that’s in there falls out of my other ear !!, Daandaman who you work for mate ...VAG or a tuning group or something

Haven't ignored you on the map and reading fella, just this time of year, back on it all tomorrow and will get this read sorted +++

We are a bunch of overly enthusiastic hobbyists, some working in the OEM automotive industry and some actually making a living doing real tuning. But the whole Audi S8 deal is just me :)

Cool! Send me your contact details when you are ready to proceed :)

So I decided to spend the money. A little spring makeover..

• Carbon Clean (walnut blast method)
• Injectors ultrasonic clean and service kit
• Front and rear lower and upper control arms
• New coil packs and spark plugs

Next job, transmission service... Then good for another 167k miles

The injectors were cleaned by James at InjectorTune. He runs a D2 S8. He provided a before and after flow rate and spay pattern report. It made sense to do them as they were out for the carbon clean anyway. It is now driving notably better and has a smoother idle.

I am very impressed with the walnut blasting. It was very effective and a lower cost than other methods. See before and after images below and judge for yourselves:

And what’s your verdict from the driving experience post clean?