The OEM setup uses separators only. DI-only engines made good separators and very good OEM oil a necessity. Toyota is not the only company without major DI carbon buildup issues. The IS250 doesn't suffer from abnormal amounts of carbon buildup either. BMW engines past the N54 again don't really suffer from this... and so on, and so on.

Anyways, "Hot" V6s (assuming 90deg.) compromise on engine balance to make turbos serviceable. Not much of a fan. Hot V8 is very obviously a different story.

Can we just have the I6 back...

 

Really complex separators that send everything back to pan or to be burned depending on what it is/droplet size/density and are electronically controlled in some cases.

Oil is sent back to the pan and combustible gas is set to the air path in front of the turbos. Works better than a catch can in some ways since there is no risk of over fill and it has a huge amount of airflow/ability to separate vs most cans.

 

The original IS250, which was the DI NA V6, suffered from the carbon build up really bad. Most other Toyota DI engines also have port injection to resolve this issue, I'm not sure if any other manufacturers have double injection systems.

 

So a simple breather has turned into $10 PCV valve, then into $300 CCV system (+2 hours labor) on BMW hot Vs, and now into a "really complex separator" system on others. The 3UZ is rolling its eyes looking down on this nonsense from heaven.

 

Well as someone who ones a 3UZ and an Audi 4.0 I actually prefer working on the Audi engine, it's easier. I have no doubt it's unlikely to last as long under typical ownership but I think under mine provided I don't blow it up with too much boost it should last quite long.

I replaced my 4.0s separator when I had the turbos off just since I was already in there and it is to an extent a consumable.....yeah not as worry free as a UZ engine but even the NA 1UR in my 460 also uses a similar system

 

Volkswagen has dual injection in Europe, but to my knowledge hasn't put it on any US-market cars.

 

I don't very much that any turbo V8 can be easier to work on than the 3UZ. The 3UZ is almost as simple to work on as GM LS engines, and with port injection and no EGR valve/pipe it does not need oil separators. There is no soot coming in, so whatever oil gets into the intake through the PCV just results in a clean, yellow oil coat, and not a greasy black gunk like most other engines.

 

Literal ease of performing repairs is higher, spark plugs for example or intakes take much less effort and time. If you ever worked on a 3uz it can get annoying with how the harness is setup vs the Audi that is designed to "loom away" from you when working and the engine is mounted in a larger bay that massively improves access to everything. You can actually drop the exhaust without jacking the car up it's so easy, set it in high mode and you have full access and since it's hot V the downpipes are very easy to get to.

The UZ also has coolant lines absolutely everywhere and they are all CT clamps, the Audi uses a distribution block that consolidated everything that tends to leak in one easy to get to place and anything up top uses quick releases. I can far more quickly and easily pull off the pump, T-stats, hoses etc from the Audi if I need to since it's all in the front left corner of the engine.

On the negative side plugs only last 20-30k miles so I guess it's good they made it so easy....

 

I believe you are confusing the 3UZ with the 1UZ. The original 1UZ was a total c-word to work on, with coolant lines everywhere, retarded clutch fan, retarded distributor design, cables, wires, and air and coolant hoses everywhere. The 3UZ improved on everything, spark plugs on it is 30 minute tops.

 

things really changed on the final revision of the 1UZ with vvti, the 3UZ is basically just a slightly more bored out vvti 1UZ

these engines use a hot V starter motor lol

 

Correct, and that starter is pretty only "difficult" job on the engine, and even then it pales compared to complete and utter clusterpluck of moderns motors.

 

No I have a 430, the UZs are getting old. The harnesses are starting to shatter and you have to be very careful with them. Everything I've done on both cars has been in favor of the Audi so far in terms of how difficult it was, nether as hard but I prefer working on the German. The 3UZ also has coolant lines everywhere and you also need to do the intake mix path cleaning that is much a pain in the *** as DI valve cleaning in that you need to take the intake off and really decarbon them. That's why you see so many posts about 430s with low or high idle or bad city mpg, the intake mix paths are to blame

 

Literally takes longer to do that starter than to swap the turbos in a hot V engine. That's kinda my exact point that the UZ is not bad to work on at all but the newer design is really simple, also important to consider since it's newer you don't run into the odd issues like breaking off knock sensor connectors. Stuff like that slows repairs and requires a lot more caution and it's just not as well designed to be taken apart.

I'm not saying the new stuff breaks less, I'm saying it's easier to deal with.

 

So does Hyundai in their recent Smartstream engines. Ford in some of their Ecoboosts as well.

Mercedes/Audi/BMW don't do it probably because that carbon buildup won't be a major issue until sometime after the warranty is used up.

 

Over here we only have the IS250 and the IS220d (lol). Carbon buildup on the IS250 is practically unheard of. BTW No longitudinal mounted GR engine has had EGR, other than the VERY latest incarnations - certainly not the 4GR/3GR. The "major" issue with the GR series, according to the Russian community at least (pretty harsh conditions for vehicles, as I'm sure you're well aware ) are the 5th cylinder dust ingress - specifically on the 3rd gen GS300/450h due to the design of the air filter box. The 5th cylinder just so happens to be the fastest path for all the junk that can potentially come through the throttle body. Carbon buildup? Pretty much no discussions on that. Same with the ~2010 Merc V6 that introduced DI - way less issues across the board compared to the outgoing V6, despite being DI-only. On the other hand, you have the early BMW/VAG attempts...