Direct Injection Only Engines
11-13-18, 06:23 AM
#1
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Direct Injection Only Engines
Have been reading about direct injection and direct injection and port injection engines, learned things I didn't know. I now know port injection cleans carbon from the back of the intake valves, direct injection does not. Here's my question, if an engine is direct injection only, is it pretty much a guarantee that you will have additional maintenance costs periodically getting the carbon cleaned off of the valves?
Leased a Hyundai Santa Fe V6 for my wife, direct injection only, not a problem because it's a lease, but will this be a maintenance issue long term? Looked up Acura MDX 3.5 engine, apparently direct injection only.
In summary how much of an issue is this long term? Could you expect to go over a hundred thousand miles and never have to deal with this?
11-13-18, 06:55 AM
#2
I doubt you'll have any issues before 100k miles. My last car was a DI engine with 96k miles when I traded it in, and I didn't do anything but 10k oil changes.
Some people install a catch can, but after watching this video, I never bothered with that.
Some people install a catch can, but after watching this video, I never bothered with that.
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Richardgil (11-13-18)
11-13-18, 08:08 AM
#3
I've had three Direct injection Hondas and followed the forums. If there were even a few documented cases of fouled intake valves on Honda's V6 and 4 cylinder engines, those forums would note and hugely exaggerate the incidents. What's actually happening is near total silence in the five years these engines have been in service. In my experience in the automotive service business, most engines, even conventionally port injected ones, develop some intake valve deposits. It usually has to get pretty bad to noticeably effect performance or fuel economy.
11-17-18, 01:55 PM
#5
I used to have an IS250 and they rebuilt the engine.
I had a discussion with my SA this morning about carbon build ups on DI engines and he said there is no permanent solution.
He said you just have to "decarbonize" the engine as part of the routine maintenance.
11-17-18, 07:27 PM
#6
Lexus Fanatic
It depends on the engine design, some DI only engines like the IS250, some Audi and BMW's have had a lot of issues with carbon buildup while others, like Honda's DI engines have not really had any issues. Honda was later in the game with DI engines and I am sure they made sure to design theirs not to have carbon fouling issues unlike some of the others.
11-18-18, 05:55 AM
#7
Pole Position
It depends on the engine design, some DI only engines like the IS250, some Audi and BMW's have had a lot of issues with carbon buildup while others, like Honda's DI engines have not really had any issues. Honda was later in the game with DI engines and I am sure they made sure to design theirs not to have carbon fouling issues unlike some of the others.
I still think it's a bit too early to tell if they will have carbon issues or not, but if they don't? I'd be interested to see how they avoided it. Some brands are going with an injector or injectors to clean the inside the ports. Of course the LS460 has both and you won't see carbon buildup problems with them...although DI engines are known for oil consumption issues and the LS460 is no stranger to oil consumption either. Some brands revise their valve covers to prevent oil from entering the PCV valve systems...or make other adjustments to the placement of the PCV system. Direct injection causes a lot of blow by, and a lot of pressure in the crankcase.
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11-18-18, 08:44 AM
#8
Doing a long term test.
7k miles on 0-20 TGMO our 60k Miles LS used one quart of oil.
Will repeat. Then 5-20 TGMO just to see.
drive the car a lot. So this will not take forever.
7k miles on 0-20 TGMO our 60k Miles LS used one quart of oil.
Will repeat. Then 5-20 TGMO just to see.
drive the car a lot. So this will not take forever.
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