Thoughts on direct injection?

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Seems like DI is becoming more and more common and is here to stay. Some people say its implementation was rushed and required more refinement. Carbon build up on engine valves seems to be a common issue. My limited understanding (please correct me if I'm wrong) on the subject is that using Top Tier gas doesn't help with build up since fuel isn't sprayed onto/near the valves in DI engines. I read about some VWs and GM cars requiring top engine rebuilds at very low miles.

What're others' thoughts?
 
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New technology, new adventures.

What's already here has gone through untold development over the years from materials, methods, systems and anything involved in that engine we pretty much take for granted.

DI will come around. Give it some time or become an early adopter.
 
Lots of debate on it. If you ask me, wait another year or two and the answer will be evident.

From what I read here, it is starting to look good. A number of early cars had problems, but as things have rolled along, the teething pains are coming to an end. And a few models seem to have skipped problems altogether.

But I plan to let others be the early adopters. Another year or two and the answers should be known.
 
Correct, the fuel doesn't go through the intake valves, so it won't have any effect on buildup. When I had the intake plenum off on my Traverse to change the spark plugs at 100,000, the buildup didn't look awful.

Just hoping the timing chains hold up, that seems to be a bigger issue on the 3.6.
 
I'm one of the "early adopters." I've owned my 2007 Mazdaspeed 3 since new. At 151k miles I've never had the valves cleaned and-based on 20 UOAs-there has never been any problems with fuel dilution. I run Mobil 1 5W-30 EP with a 7.5k OCI.
 
Pretty sure the issues with direct injection, namely the gradual occlusion of the intakes, was nailed down to certain users overly-frequently changing oil and using improper (ie: too volatile) lubricants for the job. In a nutshell, a petrol engine acts as a sort of vacuum pump on the crankcase through the PCV, and the volatile components of motor oil eventually find themselves in the intake system. In engines with fuel injection into the intake air itself, the fuel would act as a solvent and keep deposits to manageable levels with the odd throttle body cleaning. However, with direct injection, there is no natural 'cleaning' for the intake.

Implementations were tested by the manufacturers based on manufacturers' spec'ed lubes, and manufacturer spec'ed OCI's. No problems were detected. I think the manufacturers under-estimated the non-adherence of the operator community to both the recommended OCI's (more frequent isn't necessarily 'better', and can actually be, in such case, far worse for an engine), and even to the recommended oils (even dealers are often guilty of using the cheapest bulk 5W-30 dino oils they can find when they service very expensive cars!).

A couple years ago, I did a meta-analysis in a post here, where I took a thread of car owners complaining of the DI intake occlusion problem in a car-specific online enthusiast forum. And examined their stated OCI's. All of them were dramatically in excess of manufacturer's recommendations, for no reason other than the irrational belief that changing more oil more often would prolong engine life.

GM has pushed Dexos, API tightened down the volatility spec, and most vendors have engaged in campaigns to educate their operator communities that oil changes in excess of the specifications and/or OLM are not required and may be of significant detriment. I believe there has also been additional activity in terms of auditing dealers for compliance with specifications.
 
Originally Posted By: MCompact
I'm one of the "early adopters." I've owned my 2007 Mazdaspeed 3 since new. At 151k miles I've never had the valves cleaned and-based on 20 UOAs-there has never been any problems with fuel dilution. I run Mobil 1 5W-30 EP with a 7.5k OCI.


But you might have had problems if you were a 3k mi / bulk dino 5W-30 user. As many who drive those cars are. Using the Mobil1 (an oil with known low volatility on account of its synthetic make-up), and sticking with a sane OCI has likely kept you out of trouble.
 
Working at a Toyota/Lexus dealer I've seen the lack of oil separators on the early 2006-2009 models causing buildup on the valves. After seeing hundreds of updated piston ring installs it seems to have helped the earlier models. With the newer oil separators on these engines, the buildup is far less than before.
 
Originally Posted By: OneEyeJack
DI will come around. Give it some time or become an early adopter.


It has been in the mainstream for nearly 20 years; most OEMs have been using it for a long time... I think the time for early adoption has long past!
 
Originally Posted By: supton
Lots of debate on it. If you ask me, wait another year or two and the answer will be evident.

From what I read here, it is starting to look good. A number of early cars had problems, but as things have rolled along, the teething pains are coming to an end. And a few models seem to have skipped problems altogether.

But I plan to let others be the early adopters. Another year or two and the answers should be known.



I agree with this. They appear to have worked out the problems of the early models, but if I didn't need a new car, I'd hold off for just a bit longer to make sure there are no other issues before buying a direct injection car. However, if I needed a new car right now, at this point I'd go ahead and buy a direct injection vehicle, I'd just be more confident about it in a couple more years.
 
new technology? GM started using it in 2003 in Europe and 2006 in USA. I own a 2008 CTS (304hp V6 with DI) with no issues. Great thing is that it uses reg gas. My friend works as a GM service adviser and DI isn't a problem area for him. Other areas are but not DI according to him.

Dave
 
I think it is great.

Just change your oil a bit earlier and read up on deposit control.

I mean, if the mechs are used to blasting the intake valves with walnut shells or chemicals who cares.

Do it when it is called for and just pay the bit extra.

The fuel economy gains are worth it, DI is here to stay, and the issues really are no big deal.
 
I am a bit leery of DI and it seems like every new car coming out has it. I used to think "turbocharged" had hotrod status, and now many everyday driver cars have turbos. GM 3.6 DI engine would be a deal breaker for me considering the timing chain problems, although many people have not had issues with them. A friend of mine would have had to pay $4000 out of pocket because his Acadia needed new chains at 96,000 miles. Luckily his warranty covered it as well as a new water pump. Had to drop engine out to do it.

I am sure in coming years, DI will be the norm and there will be nothing to do about it anyway. DI, mandatory stop/start technology, AFM, turbos, on tiny engines make my want to keep my older vehicles that much longer. I'm waiting for Ford to introduce a 2 cylinder engine to cram into a their smallest car maxed out with everything but the kitchen sink, all in the name of efficiency. Hard to believe, but the 2016 Malibu's largest engine option will be the same size that is in my beater Camry now that I always thought was smallish. The standard Malibu 1.5 L DI turbo will have a whopping 160HP. Progress....? Wonder if that engine will reach 310k like the Camry?
 
Originally Posted By: mclasser
Seems like DI is becoming more and more common and is here to stay. Some people say its implementation was rushed and required more refinement. Carbon build up on engine valves seems to be a common issue. My limited understanding (please correct me if I'm wrong) on the subject is that using Top Tier gas doesn't help with build up since fuel isn't sprayed onto/near the valves in DI engines. I read about some VWs and GM cars requiring top engine rebuilds at very low miles.

What're others' thoughts?


The bolded part should say a "common concern" not a common issue. DI has been around for 50+ years. It is just now getting popular.
 
Originally Posted By: pitzel
Pretty sure the issues with direct injection, namely the gradual occlusion of the intakes, was nailed down to certain users overly-frequently changing oil and using improper (ie: too volatile) lubricants for the job.


elaborate, or stop making up trash like the 40k OCI is okay thread.
 
Originally Posted By: cptbarkey
Originally Posted By: pitzel
Pretty sure the issues with direct injection, namely the gradual occlusion of the intakes, was nailed down to certain users overly-frequently changing oil and using improper (ie: too volatile) lubricants for the job.


elaborate, or stop making up trash like the 40k OCI is okay thread.


Not sure which part you are concerned about but there have been studies pointing to early oil changes being contributing causes. More mass flashes off of fresh oil than used oil. So more oil changes increase the amount of mass transferred to gas within the sump that then travels back through the PCV.
 
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