Direct Injection

[Papasonic]

I am not entirely sold on D.I. yet. I know that eventually this technology will be commonplace industry wide. My concerns are based on information obtained by owning a 2011 Chevrolet Equinox with a 2.4 DI engine, and a related forum threads and posts. Concerns are:
1. Excessive, and premature oil contamination; seems common with all makes with DI.
2.Potential for raw fuel introduced into crankcase via defective high pressure fuel pump; (bolted to engine, driven by camshaft). The Equinox has had four different part numbers or more for this one component. It has had issues with seals failing internally, and raw fuel enters the crankcase/oilpan causing oil dilution and related lubrication failures.
3. Excessive hydrocarbon (soot) deposits in the exhaust system leading to contaminated O2 sensors, and catalytic converters.
4. Potential for excessive intake valve deposits; due to no fuel mixture passing intake port.

These are my observations of DI technology in use today. Obviously it is here to stay because of its many benefits, but I believe GM has a little more homework to do on its DI systems to resolve some of the issues.
So far, at least with my GM manufactured vehicles, I have more confidence in the non DI offerings.

 

[laborsmith]

Good summary, Papasonic. I believe once #2 is resolved, that will take care of #1 and #3. Four numbers for the same part! And likely still searching for one that will do the job.

I suspect the only answer for #4 is the catch can or something very similar. This problem is not exclusive to GM and BMW and Mercedes-Benz boards have too many posts related to what you describe as problem #4 to ignore.

Once the intake is clogged, the upper engine has to be removed and cleaned with walnut shell blastings or something similar. Seafoam can have an ameliorative effect if properly introduced before things get to bad, but the buildup never is completely removed. There is speculation that the companies have figured out how to keep the build up from getting to bad for 100,000 or so miles. I wonder how long a modern engine (power train) warranty lasts?

If you have ever had an engine rebuilt you will have an idea how much it costs to resolve the build up.

But you do get a more efficient fuel burn thus more power per unit of fuel.

Laborsmith

 

[sx sonic]

DI is really cool and has a lot of benefits but I agree with ur post Papasonic & laborsmith, the systems just isn't there yet.

I've heard audi had some really really bad issues with carbon buildup and when I left BMW in 08 they were having some issues with the high pressure fuel pumps (mind you it was fairly rare and intermittent, but there nonetheless)

 

[RS Turbo]

Di is hear to stay. If there is any issues with excessive fuel as you claim there would be a SES Lamp turned on before any major issues for fuel delivery. Gm is recommending Top Fuel Engine cleaner to correct the intake build up issues that are found. The Walnut shell blasting is done with the intake still on the engine there is no disassmbley needed this was done in the mid 90s . Engineering is way farther along than you think. It will probably be a maintenance item to have your intake cleaned with Top Engine cleaner or several changes made to the PVC system.

You need to remember there is a Stochiometric window of 14.7 to 1 ratio the ECM will always compansate injector timing to keep it in with emissions. If fuel trims start to move to far apart again the SES lamp will warn the driver that there is a issue.

Here is some food for thought:
If you are getting 40 MPG that engine is using 128 Oz divided by 40 miles is about 3oz per mile, now divided by the # of cylinders of 4 is actually now only .75 of an oz per cylinder per mile at about 2000 RPM.

So at 60mph for easy calculations 2000 RPM, the Injector is opening 1000 times injecting .0075 of an oz per cylinder. That injector is on and off 10 times before you can blink your eye... with DI the injector psi is thru the roof to compansate for the high psi of compression, This can only be achieved thru a Mechanical pump driven off the cams.

If your oil was extremley comtaminated with fuel enough to have damage the oil level would be changing.

 

[Papasonic]

If your oil was extremley comtaminated with fuel enough to have damage the oil level would be changing.

That is precisely what is happening on some of the 2.4 DI engines installed in the Terrain and Equinox. The oil level rises as raw fuel enters the crankcase due to insufficient seals in the high pressure fuel pump. There is a bulletin on GM Techlink describing the procedure to substantiate excessive oil consumption on the 2010 2.4 DI engine. The excessive oil consumption appears to be caused by damage due to insufficient lubrication from fuel diluted oil. The inspection requires disassembly of the cylinder head assembly, and looking for zebra stripes, as they call them, on the cylinder walls, or cylinder scuffing. The repair is to install a new engine assembly; as all internal components have suffered from insufficient lubrication.

Search Results Equinox oil consumption

Here is a link to the tech site. Although the article doesn't actually provide the root cause of this failure, in my opinion it clearly shows damage from insufficient lubrication; and how can this occur? From lubricating oil diluted and contaminated by fuel from a faulty DI fuel system. A lot of what I have just submitted is my opinion, but with a healthy dose of common sense.

I still believe GM has issues regarding their DI engine program that need resolution.

Papasonic

 

[RS Turbo]

That is precisely what is happening on some of the 2.4 DI engines installed in the Terrain and Equinox. The oil level rises as raw fuel enters the crankcase due to insufficient seals in the high pressure fuel pump. There is a bulletin on GM Techlink describing the procedure to substantiate excessive oil consumption on the 2010 2.4 DI engine. The excessive oil consumption appears to be caused by damage due to insufficient lubrication from fuel diluted oil. The inspection requires disassembly of the cylinder head assembly, and looking for zebra stripes, as they call them, on the cylinder walls, or cylinder scuffing. The repair is to install a new engine assembly; as all internal components have suffered from insufficient lubrication.

Search Results Equinox oil consumption

Here is a link to the tech site. Although the article doesn't actually provide the root cause of this failure, in my opinion it clearly shows damage from insufficient lubrication; and how can this occur? From lubricating oil diluted and contaminated by fuel from a faulty DI fuel system. A lot of what I have just submitted is my opinion, but with a healthy dose of common sense.

I still believe GM has issues regarding their DI engine program that need resolution.

Papasonic

I am fully aware of this issue and the issue is the piston rings that were installed were believed to be the incorrect ones during assembly. That is why the engine is being replaced there is cylinder damage. The rings need to rotate and not stay in the same position on the piston during operation. If you read it closer you will see they take about stuck rings. This has NOTHING to to with DI. Note the complaint is oil consumpsion. Oil Consumption has to do with 4 possible things, Piston rings, Valve seals, PCV or leaks. I have worked with Jamie for 14 year and he is excellent at what he does. I have been doing this work for over 22 year as well.

Nearly every 2.4L early build will end up with an engine replaced for this but not for the condition you believe.

If you want to speak of engine issue then lets talk about V6 Timing chain noise.

They stand behind it to 100k miles and most new car buyer usually off the vehicle before 70k.

So really is there anything to worry about! Na Engineering has all the worring to be doing.

 

[Papasonic]

Another issue I personally have noted on my DI fueled 2.4 Chevy Equinox is the hydrocarbon (soot) deposits in the tailpipe. The deposits make it look as if I have a diesel fueled engine under the hood. In comparison: The tailpipe on both my 5.3 Silverado, and my 5.7 LS1 GTO are absolutely free of any sooty deposits. I took the Equinox in to my dealer when I noted this issue; they looked at fuel trim, HPFP leakdown, and various other related potential problems, and determined that there was no problem. I then asked the service manager if he thought that it was normal to have soot in the tailpipe. He said that he would inspect other similar vehicles as they came in for service. He called me about two weeks later, and said that he noted all of these 2.4 DI engines had similar tailpipe deposits. He had no explanation, but as they all exhibited this deposit he deemed it normal. My thoughts are how can the vehicle possibly meet emission requirements with unburned hydrocarbon emissions deposited in the tailpipe, and how will this ultimately affect the O2 sensors and catalytic converter operation with a layer of carbon/soot on these components.

This is a few of my personal observations of a DI fueled GM manufactured vehicle that I own. That is why I suggest that there are still unresolved issues with DI fueled GM engines that still exist.

Papasonic

 

[RS Turbo]

Another issue I personally have noted on my DI fueled 2.4 Chevy Equinox is the hydrocarbon (soot) deposits in the tailpipe. The deposits make it look as if I have a diesel fueled engine under the hood. In comparison: The tailpipe on both my 5.3 Silverado, and my 5.7 LS1 GTO are absolutely free of any sooty deposits. I took the Equinox in to my dealer when I noted this issue; they looked at fuel trim, HPFP leakdown, and various other related potential problems, and determined that there was no problem. I then asked the service manager if he thought that it was normal to have soot in the tailpipe. He said that he would inspect other similar vehicles as they came in for service. He called me about two weeks later, and said that he noted all of these 2.4 DI engines had similar tailpipe deposits. He had no explanation, but as they all exhibited this deposit he deemed it normal. My thoughts are how can the vehicle possibly meet emission requirements with unburned hydrocarbon emissions deposited in the tailpipe, and how will this ultimately affect the O2 sensors and catalytic converter operation with a layer of carbon/soot on these components.

This is a few of my personal observations of a DI fueled GM manufactured vehicle that I own. That is why I suggest that there are still unresolved issues with DI fueled GM engines that still exist.

Papasonic

A lot of vehicles show Soot at the tail pipe look around, My 2008 Aveo had that and it is not DI injected. If it was affecting your emissions because of running rich it would have turned on the SES lamp. Could be what you are seeing is normal for the metal used for that exhaust system may seem to attract more carbon/soot, you are also comparing 4 cyl to V8. A byproduct of the combustion is Water if you have a similar size pipe with twice the water vaper leaving it this could be why your not seeing it on the other vehicles.

Something to think about.... Compare apples to apples, not Apples to oranges...

What is the metal on all the exhaust tips, Are they different?

Is the same fuel station used to fuel all vehicle and same grade of fuel used?

 

[laborsmith]

Does not. Chevy was informed a year ago of the mistake.

It does not have DI because the 40mpg target was hit w/o DI.

I posted some months back that I believe it will but I do not believe DI for the 1.4t in the next couple of years. But at least the engineering is done.

Laborsmith

 

[Larry]

Direct injection is not new technology, it was used in the mid-1900s on cars and possibly earlier on aircraft engines. It has many benefits, but it is expensive and there are still some issues to be worked out. Toyota has the most advanced DI system currently, but even it has issues.