Carbon issues with direct injection engines

[Engineer]

So the addition of port injectors back is truly going backwards when it is so easy to prevent all of this in the first place.

Not sure what you mean easy to prevent? You talking about ditching direct injection and simply going back to port injection full time (with the other benefits lost) or did I miss something (I usually do)?

 

[JulesMaximus]

Anyone know if this is a problem for Mercedes engines? We just bought a CPO CLS550 with the 4.6l twin turbo V8. How would this problem manifest itself in this car?

I guess if we don't have any codes I won't worry about it.

 

[Jimzz]

Anyone know if this is a problem for Mercedes engines? We just bought a CPO CLS550 with the 4.6l twin turbo V8. How would this problem manifest itself in this car?

I guess if we don't have any codes I won't worry about it.

European cars have been the worst at DI.

I would spray out the throttle body and intake every 10k on it if you plan to keep it a while.

Carb cleaner works ok but there are special cleaners that are supposed to be better like this...

http://crcindustries.com/auto/intake-valve-cleaner.php

 

[eng2d2]

How does one determine if you have direct injection? Is there a database which cars have direct injection?

 

[JulesMaximus]

European cars have been the worst at DI.

I would spray out the throttle body and intake every 10k on it if you plan to keep it a while.

Carb cleaner works ok but there are special cleaners that are supposed to be better like this...

http://crcindustries.com/auto/intake-valve-cleaner.php

We have our next 3 services free and almost 4 years more of extended warranty with unlimited mileage so I'm just going to drive the crap out of it and take it to the dealership if anything goes wrong.

 

[shabby]

We have our next 3 services free and almost 4 years more of extended warranty with unlimited mileage so I'm just going to drive the crap out of it and take it to the dealership if anything goes wrong.

"Im sorry Mr Maximus but this is not covered by warranty, its preventative maintenance just like cleaning the throttle body" ...is what i assume they would say.

Im sure my 2.0L ecotec turbo is due for a cleaning its got like 140000km.

 

[Accord99]

How does one determine if you have direct injection? Is there a database which cars have direct injection?

It's usually that would be shown in the specs (such as on the website) as it's a selling feature. The sound of the high pressure fuel pump required for DI in operation is usually noticeable as well.

 

[LTC8K6]

They will have to do something, because GDI is quite the particulate emitter...


https://en.wikipedia.org/wiki/Gasoline_direct_injection#Emissions

 

[JulesMaximus]

"Im sorry Mr Maximus but this is not covered by warranty, its preventative maintenance just like cleaning the throttle body" ...is what i assume they would say.

Im sure my 2.0L ecotec turbo is due for a cleaning its got like 140000km.

Meh, whatever. As long as it's not thousands of dollars I'm fine with it.

 

[sontakke]

GDI

Can you recommend a safe cleaner to unclog EGR passages? I am looking for something equivalent to Mr Plumber but safe for automotive use, especially for aluminum parts.

I am facing persistent P0401 on Honda V6 engine and usual cleaning of the intake plenum has not fixing the problem. I am afraid that crazy path from the engine block to the EGR valve has a blockage and is impossible to snake through.

 

[bruceb]

P0401 indicates a misfire with Cylinder #01 ... if it was P0400 indicating random misfires with no specific cylinder indicated, then I would suspect carbon buildup or an ingition module failure. In your case, start with a New Spark Plug (be careful not to overtighten or crack it) If that does not do it, change the Plug Wire or if it is Coil On Plug try a new coil or swap it. If the trouble moves to another cylinder, then you have found the culprit.

 

[Jimzz]

Meh, whatever. As long as it's not thousands of dollars I'm fine with it.

He's right; most do not consider it a warranty item. And for that car I bet it is thousand+ as to REALLY fix you have to pull the intake off and blast the intake and valves.

I would ask the manufacture in writing if it would be covered if it becomes a issue.

 

[Engineer]

He's right; most do not consider it a warranty item. And for that car I bet it is thousand+ as to REALLY fix you have to pull the intake off and blast the intake and valves.

I would ask the manufacture in writing if it would be covered if it becomes a issue.

I have seen some estimates (from forums for walnut blasting) from BMW dealers as high as $1,750. Doing a search, I found BMW dealers as low as $350. I've read that you can get it under $300 from local shops.

 

[echo4747]

I have seen some estimates (from forums for walnut blasting) from BMW dealers as high as $1,750. Doing a search, I found BMW dealers as low as $350. I've read that you can get it under $300 from local shops.

I am sure the price will vary a lot ... much of it will depend on the engine type and the time it takes to remove and replace intake manifold and other associated parts necessary to access the the back of the valves. I dont think parts should be too much (probably a couple gaskets, and walnuts shells or whatever media used to blast the deposits off.) Labor is the big item with this job

 

[sontakke]

P0401 indicates a misfire with Cylinder #01 ... if it was P0400 indicating random misfires with no specific cylinder indicated, then I would suspect carbon buildup or an ingition module failure. In your case, start with a New Spark Plug (be careful not to overtighten or crack it) If that does not do it, change the Plug Wire or if it is Coil On Plug try a new coil or swap it. If the trouble moves to another cylinder, then you have found the culprit.

I wish you had not answered this. You write so authoritatively but you are so wrong! P0401 is Insufficient EGR flow. Let the person for whom this question was intended answer it.

 

[evident]

thank goodness this isn't an issue for the Lexus 3.5L V6. It's apparently a DI engine but also has port injection to clean up any carbon buildup.

 

[LTC8K6]

thank goodness this isn't an issue for the Lexus 3.5L V6. It's apparently a DI engine but also has port injection to clean up any carbon buildup.

That goes all the way back to 2005. D-4S system.

The very latest versions of the V6 do a "self clean" cycle every once in a while to clean the carbon off the injectors.

 

[Midwayman]

Anyone know if this is a problem for Mercedes engines? We just bought a CPO CLS550 with the 4.6l twin turbo V8. How would this problem manifest itself in this car?

I guess if we don't have any codes I won't worry about it.

After this thread started I went and looked for mine (M276 GDI) and couldn't find any stories of people complaining about it. Just speculation if it had it like other cars. One person mentioned that M276 shared a head design with the v8 (though shorten) where the back of the valves is able to be sprayed by the injector inside the chamber. Hardly a definitive answer, but if it were a big problem I'm sure it would be easier to find threads on it.

 

[GDI Tech]

Not sure what you mean easy to prevent? You talking about ditching direct injection and simply going back to port injection full time (with the other benefits lost) or did I miss something (I usually do)?

One of the few actually effective PCV air/oil separation systems (most are only trapping a very small portion and do little to help) this stops approximately 95% of the coking by stopping the compounds from reaching the valves to begin with, but these require the owner to empty at least every oil change and dispose of as one would with drain oil. You cannot return what these catch to the crankcase as it is a concentration of damaging compounds along with engine oil.

Here are a few examples of the systems that do actually trap 95% plus of these compounds:

http://themustangsource.com/forums/f726/jlt-vs-rx-catch-can-results-part-2-a-532449/

https://www.youtube.com/watch?v=rpAzRGw46eg

https://www.youtube.com/watch?v=H3mFpPPd1Rk

https://www.youtube.com/watch?v=dT0kpHpGQJ8

The Ford ecoboost engines have one of the poorest designed PCV systems from the factory and also cause this, which is way excessive. Every engine has these issues and every automaker claims they either do not, or they have now solved it (false).

Elite Engineering and the RX systems are available for most any vehicle, but some may need "creative: thinking in mount locations, etc. But they have good tech support to guide most anyone.

Colorado Speed has a proven one as well, but limited applications.

Anyone know if this is a problem for Mercedes engines? We just bought a CPO CLS550 with the 4.6l twin turbo V8. How would this problem manifest itself in this car?

I guess if we don't have any codes I won't worry about it.

Yes, there is not a single GDI engine that does not, but back a few pages I have gone into great detail in how each is attempting to prevent these issues, and some have made improvements, but none have solved it even close to how an actual system designed to work does.

European cars have been the worst at DI.

I would spray out the throttle body and intake every 10k on it if you plan to keep it a while.

Carb cleaner works ok but there are special cleaners that are supposed to be better like this...

http://crcindustries.com/auto/intake-valve-cleaner.php

Again correct, but the solvent based cleaners used while engine is running at best (from their claims, CRC, Seafoam, BG, etc. only can clean UP TO 40% of these), and that does nothing to prevent the valve guide wear occurring, and as these deposits are what is referred to as "hard carbon" vs older port injection engines "soft carbon" will cause some engine damage in most every use as these hard crystalline deposits break loose, smaller particles are forced between the piston and cylinder walls and scouring results. And bent valves and damaged catalytic converters as well. Then, if you have a turbo equipped engine, the hot side turbine blades are damaged when these hard particles impact them as they come loose and exit the exhaust ports and impact the leading edges of the turbines. Ford has several TSB's out concerning this and I imagine BMW/Mercedes, etc. also do. Only a manual cleaning can clean these properly. The crushed walnut shell media blasting or the brush method are the only two real effective procedures.

Will add more reply's next.

 

[GDI Tech]

He's right; most do not consider it a warranty item. And for that car I bet it is thousand+ as to REALLY fix you have to pull the intake off and blast the intake and valves.

I would ask the manufacture in writing if it would be covered if it becomes a issue.

This is usually not a warranty covered item, but some have replaced heads or sent out heads for manual valve jobs under warranty. Ford was for a couple of years replacing the cylinder heads so they could study them, but discontinued that. Price your correct on as well. The newer BMW mini engines now have the intake manifold in the front of the engine to reduce labor time to remove for cleaning. Prior they were in the rear jammed between the firewall and very difficult to remove for cleaning.

I am sure the price will vary a lot ... much of it will depend on the engine type and the time it takes to remove and replace intake manifold and other associated parts necessary to access the the back of the valves. I dont think parts should be too much (probably a couple gaskets, and walnuts shells or whatever media used to blast the deposits off.) Labor is the big item with this job

Walnut shell media is pricey, but can be reused until the deposits start to clog the blast nozzle.

thank goodness this isn't an issue for the Lexus 3.5L V6. It's apparently a DI engine but also has port injection to clean up any carbon buildup.

They do, and nearly as bad as any of the others. Want to see? Remove your IM and see the valves up close, or snake a boroscope down the intake manifold with the throttle body removed. Most automakers have or are adding in the small port injectors, but they do too little and only slightly reduce the rate of formation. This helps some, but the trade off is increased detonation incidence again. This causes the knock sensors to signal the ECU to pull timing, and then power and economy are reduced. There is a version of the air/oil separating systems that does not need to be drained (self draining yet meets emissions) but that is still 3-4 years away before any automakers will have them standard. The entire benefit of GDI is to have no explosive/combustible mixture present during the compression stroke.

ALL auto makers GDI engines have this and none have stopped it.

There are articles on every engine as long as techs have posted their findings, but all automakers deny this:

http://mbworld.org/forums/c-class-c...-up-new-direct-injected-mercedes-engines.html

http://www.benzworld.org/forums/w204-c-class/2462321-gdi-intake-valve-carbon-fouling.html

Lot's of examples, but the best is to Google: "GDI Intake valve coking" and click on images. You will find actual pictures of most any engine you can imagine showing what is really occurring, and remember, NO port injection engine will show coking at all, even after several hundred thousand miles due to the detergent fuel constantly cooling and keeping them clean. Once the deposits form detergent fuel cannot clean what has already formed.

 

[echo4747]

i wonder if dry ice blast would be a better alternative than walnut shells. It would sublimate in the event any blasting media strayed. Stray bits of walnut shells left behind certainly cant do any good.

 

[GDI Tech]

gpse, I got your PM but cannot reply until I have 25 posts. Wrote a long reply with detailed pictures and instructions for you, but lost it as it won;t let me PM you yet.

On the EGR coking, the only real method is to disassemble and manually clean the circuits, and generally is best to replace the EGR valve it'self. This is not easy, but use a shop vac to suck up all deposits as you can while doing it.

Almost all newer engines now have done away with EGR valves and use a variable valve timing EGR emulation as this was such an issue in the past.

 

[GDI Tech]

That goes all the way back to 2005. D-4S system.

The very latest versions of the V6 do a "self clean" cycle every once in a while to clean the carbon off the injectors.

i wonder if dry ice blast would be a better alternative than walnut shells. It would sublimate in the event any blasting media strayed. Stray bits of walnut shells left behind certainly cant do any good.

Hmmm, never considered that. Any manual cleaning you must make sure the valves (most of these engines have 2 intake valves per cylinder now) are completely closed in the cylinders your working on (bring to TDC) and you tape off the other ports where any have open valves so no debris can enter them. Then blast with the proper adapter and these have a shop vac connection to suck out all debris as your blasting. Then use compressed air nozzle to blow out any remaining before moving to the next. Dry ice may be a viable media....good thinking. It leaves no liquid behind to turn the results to "mud". You may be onto something!

If using the brush method, use a solvent like the CRC/seafoam/etc. and soak the valves in the ports your cleaning for at least 15-30 minutes to loosen the deposits and then the brushes used with a cordless drill or die-grinder works well. A cheap universal shotgun cleaning set has a good assortment of brass brushes and works well. Always use a long shaft screw driver to scrape the larger deposits loose first before using the brushes. You will need to repeat 2-3 times with the brush/solvent as these are very hard and baked on and difficult to remove.

 

[echo4747]

GDI Tech, When comparing port injection to direct injection. which method delivers more complete combustion? (assuming each engine optimally tuned)

I wonder if more research is need on developing better anti-knock fuel additives which would allow higher compression ratios and port injection

 

[bruceb]

Direct injection produces more power and better fuel economy. The trade off right now is the carbon build up on the intake valves. It may be, as you just alluded to, a need for a totally reformulated type of gasoline, so deposits do not build up as easily. You can thank all of this crap on Obama and the EPA wanting better (and it is not really much better) fuel economy.