Direct injection, has a dirty secret.

[EddieS'04]

Intresting article...

 

[Richard L]

Good article, but it seems odd that the engines with DI would have a problem with carbon build up on the necks of the intake valves??? The valve should be closed when the injection takes place and the neck of the intake should be shielded from any fuel or combustion deposits.



It was noted that the the carbond deposit issue has been mostly resolve, and I assume it was done by delaying the injection of fuel after the bolt intake and exhaust valves have closed???



Even if it is still a small issue, it would be smart to add a good cleaner like Seafoam on a periodic basis just to eliminate the carbon build up.



...Rich

 

[Doctor CAD]

Seafoam wouldn't do anything in a GDI. The carbon is upstream of the gasoline path, and thats where the majority of the Seafoam would be. It might help a little, but maybe thats why there IS a buildup.



Now that it is well documented, technology will be developed to fix the issue.

 

[Richard L]

doctorcad,

Seafoam is injected into the intake which would clean intake valves as follows:

From the Seafoam Website:



Use Sea Foam Spray to clean carbon deposits from the intake systems, intake valves, and combustion chambers of your engine. Not for use on Diesel Air Intake Systems.



Use Sea Foam Spray to clean all these areas with the cleaning tube inserted into the sealed air intake system to spray Sea Foam into the engine from in front of the throttle plate. See side panel for illustration.



Warm up engine and turn off all accessories.



Shut engine off.



DO NOT use in enclosed area, make sure exhaust is well ventilated

DO NOT use a scan tool to increase RPM via the air by-pass valve

DO NOT spray Sea Foam into the mass airflow Sensor

Locate the engine throttle body and remove air intake boot. Install the Sea Foam cleaning tube by inserting the short end of the hook guide into the throttle body, positioning the tube directly in front of the throttle plate. Ideal placement of hook guide is at top center of throttle body housing (12 oclock.) Place end of cleaning tube within of throttle plate by adjusting cleaning tube in or out of hook guide. Replace air intake boot to hold cleaning tube assembly in place.



With the vehicle in park or neutral and parking brake engaged start engine and increase idle speed 500 to 1000 RPM above factory idle specification. Increasing engine RPM is important for the following reasons:



The Sea Foam cleaner must be evenly distributed

The Sea Foam cleaner must fully atomize

The Sea Foam cleaner must pass through the throttle body, not the air by-pass

Find a method to hold engine RPM steady as this application takes approximately 5 minutes



After can of Sea Foam has been used, approximately 2-3 minutes, stop spray, return engine to normal idle speed and shut off engine.



Remove cleaning tube from throttle body and reattach air inlet boot to throttle body and tighten clamp.



Let vehicle sit about 5 minutes then restart in a well ventilated area, as exhaust may be extreme for a short time. Road test, driving aggressively, to remove any remaining carbon. REPEAT Sea Foam TREATEMENT AS NECESSARY.

...Rich

 

[Doctor CAD]

I generally add it to my tank. Never did the vacuum hose thing.

 

[EddieS'04]

I have wondered about the vaccum hose Idea. Usualy on most FI intakes. An available vacuum hose is at one end or the other of the upper intake plenum. Will the sea foam get to all cylinders?



The info Rich posted, makes more sense that the vaccuum hose idea.



Caburated motors always have, at least one large vacuum source. On the carburator or the spacer. Central to the intake.



Also my uncle that retired from a petro company. He was in engine research. He told me that all additives were snake oil. he only recomended sea foam for small engines. He said, modern FI automobiles dont have the problems of carbon and other build ups. That are advertised. As long as your ignition and ECU is performing properly.



He said, the best thing was to use tier one gas. To never use the same brand gas continously. One companys detergent additives would clean the deposits, the others didnt. Has to do with different formulations. Unleaded fuel is not like the leaded old days.



He did say it can help to use a bottle of chevron thechron. In the tank every 15K, but not necesary, if you got on the highway regular enough. BTW chevron was his competitor..LOL.



Since my mom is 81 and never gets over 50mph. He recomended that I put a bottle of techron, in her grand marquis every other oil change. Take it on the back country roads where she lives. Drive it at 80mph for at least 20miles. Also do a few WOT's.



I trust his opinions. Not only 'cause of his research experiance. But 'cause he is a gear head also.

 

[Richard L]

Eddie,

my uncle that retired from a petro company. He was in engine research. He told me that all additives were snake oil. he only recomended sea foam for small engines. He said, modern FI automobiles dont have the problems of carbon and other build ups. That are advertised. As long as your ignition and ECU is performing properly.

I have to disagree, and most automotive mechanics will tell you that carbon build up in the intake and throttle body is very problematic on most modern engines. I submit that it is not due to the fuel, but rather due to the recycling of exaust gases, and crankcase fumes (PCV) back into the intake stream, but for what ever the reason...it is very common in nearly all modern FI engines.



I think we all know about the necessity of cleaning the Sport Trac's IAC and trottlebody, and that carbon also builds up on the intake, but it most troublesome when the intake air stream is necked down like in the IAC valve, the throttle body, and intake valves.



With a wet intake, the fuel tends to wash down any carbon particles before they become a problem, and that's probably why the DI is having problems with carbon build up on the back side (neck) of the intake valves.



...Rich

 

[Jim Mills]

I do seafoam in all my vehicles every 25k. When you pull the hose off the booster the vehicle will want to die. I put my thimb over it until I stick it in the cup. Its a great service you'll be amazed how much buildup comes through the exhaust. You neighbors wont like it much! If its really bad its like a fog machine on wheel for 2 or 3 miles. I credit this service to keeping my 01 so responsive.

This thread caught my eye because I'll be in a DI class in about 2 weeks.

 

[scott degroot]

I couldn't agree less with that article. I can't count the number of engines over the years that I have had apart, upwards of 1000 if I had to guess, and deposits on the backside and neck area of the intake valves is pretty common on port injected engines...granted some are worse than others. I fully believe that the buildup has everything to do with the pcv system. FWIW some fo the worse engines I have seen for valve deposit buildup are the GM 3.1, 3.4 and 3.8 liter engines all of which are port injected. On the flip side 2 of the best engiens that I have seen are the VW 2.8 liter v6 30 valve , I had one of these apart at 80k and the intakes valves looked as if they were brand new. The other one was the 4.0 on the ST that I picked up not long ago, when I pulled the heads on it at 160k the valves were spotless and the top of the pistons had almost no carbon buildup.

 

[Richard L]

I1tech,

I agree with your assement. I suspect that the majority of the carbon build up on port port injected engine is due to the PVC and EGR gasses dumped into the intake, and perhaps the different injector angles in relationship to the intake valve angles. Some engines wash the valve of deposits better than others



....Rich

 

[EddieS'04]

I have to admit. My uncle retired 10yrs ago. He has been out of the loop.

I will have to be more careful and reseach what he tells me.

Sorry guys' I wasnt trying to sound like a know it all...

thanks

 

[Richard L]

Eddie,

You do not need to applogize for anything. That's the best part of this site is that for the most part we can discuss different ideas and theories intelligently, and I think we all can learn something, or at least accept someone else point of view even if we don't agree.



I initially thought it was odd that carbon was building up on the back of the intake valve on the DI engines. After I thought about it, I realized that it probably is not a fuel related issue, but related to the PCV or EGR gases being dump into the intake. and that a typical port injection engine may have kept the valve clean by spraying the fuel right behind the valve and wash the valve of carbon build up. I can't prove I am right and l1tech probably cannot give scientific evidence that his theory is right. I do think that carbon build up in the intake has become a more significant issue since the auto industry changed over to port injection.



...Rich

 

[rob chaw]

Thanks guys reminds me to do seafoam soon...



:banana: :banana: :banana:

 

[Richard L]

Rob,

Yes it is a good idea to use Seafoam or other intake cleaners, however be aware that Seafoam does not really do much to clean the notorious IAC (Idle Air Control valve). This is because you have to run the engine faster than idle when injecting the Seafoam, so the IAC is not drawing any air in and also no Seafoam. So you will probably have to still clean the IAC separately, but it's a relatively simple task.



...Rich