DI Engines; Krud Fouled Intake Man'd & Intake Valves

[KevinK2]

I've searched here in vain .. looking for forum links if they are there, or a new discussion of this problem, where substantial build-up occurs at 20-30K miles. Is this just a DI + Turbo problem, or NA DI/DGI engines also? (Gas only in this thread)

VW has a solution for 2013, using low pressure for port injection at low loads for fuel detergent cleaning.

Mazda had an unresolved problem with their 2006-2007 MazdaSpeed6.

MB just introduced DI for 2012, but their technical department is mum on the subject.

If the pic comes up, it's of a porche with DI.

Thanks, Kevin

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[KevinK2]

Another pic of Mazdaspeed 6 (turbo DI) looking in intake ports in head.

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[MikeHalloran]

Don't they all feed crancase fumes into the intake? Duh.


Mike Halloran
Pembroke Pines, FL, USA

 

[BrianPetersen]

Crankcase fumes + EGR with carbon particles in it is going to make a mess. Earlier VW diesels had trouble with this, also. The later ones have fixed this by having more efficient combustion systems that make fewer carbon particles and presumably better separation of oil in the crankcase fumes. (I have a 2006 with over 300,000 km on it and it hasn't been an issue.)

Some Toyota engines have been using direct injection plus port injection for some time.

I don't know why some DI engines have been trouble and others haven't, but I can think of a number of potential factors. Cam timing may have something to do with it. Avoiding reversion flow in the intake ports during overlap (or not having overlap ...) may have something to do with it. Organizing the combustion process so that under the circumstances when it is using EGR, it is not making carbon particles, may have something to do with it.

 

[KevinK2]

Cam timing may have something to do with it. Avoiding reversion flow in the intake ports during overlap (or not having overlap ...) may have something to do with it.

I recently spoke with a DI consultant for Ford, and he inferred exactly what you spoke of. He also spoke of "special" injectors that minimized deposits.

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[LadaTrouble]

Mitsubishi were doing GDI in the '90's - they used a lot of EGR and intake deposits are still a major problem as these vehicle are still use here in NZ.

 

[BrianGar]

Happens the VAG petrols too, really bad.
Direct injection + crankcase mist - fuel mist 'cleaning power' = mess.

I spoke with a designer a long time ago when the issues started showing themselves and he more or less stated that by the time it was clear it was a major problem, they had progressed too far and had to keep it going.

I wouldn't touch a Di petrol having looked at a lot of fouled up heads.
Keep in mind this engine requires proper tumble flow for complete combustion. Not until they add a shower type injector in the intake that comes in at higher rpm would I want one.

Some of the deposits are also from the valve stem seals weeping - just incase anyone spends £££££ designing a crank case mist separator.

The above problem was the first thing that came into my head back in 2007 when watching the video below.

http://www.youtube.com/watch?v=PqZXyHp9cPk

I think crankcase mist is just as big of a problem as egr, and baking onto said areas at shutdown.

I would think a car that spends more time at optimum rpm(lower valve seal vacuum), and one that does less short runs would escape better.

Brian,
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[KevinK2]

Mercedes just introduced 2 new DGI engines C350 and Turbo C250. Hard to imagine they did not have a fix for this problem, but persistent calls about it go unanswered. Especially since VW had such a big problem earlier and showed their new 2013 dual "hi-low" pressure inj system (see link).

Right now, it seems like it's just turbo'd engines ?? For the crankcase vapors, could add an oil air separator (81 924 Turbo)from crank case to air filter, and a PCV valve with a well designed catch can, with enough capacity to only require emptying at oil change intervals.

Lada Trouble, were those Mitsubishi''s turbos?

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[KevinK2]

Thanks for the youtube link Brian.

If you check the eco-boost Ford clip (no sound) it appears the DI nozzle is angled such that part of the faned spray washes the back of the intake valve. Looks good for cleaning the intake valve.

http://www.youtube.com/watch?v=73BrXCsbd64&feature=related

 

[BrianGar]

All the Vw fsi's are n/a.

Your welcome for link, yours is interesting also.

I dont think people would, or like emptying catch cans. The secret of a good catch can is to keep it hot, either with bay heat, conduction, or a coolant heat exchanger. This usually means removal can be a pain.

Below is the Patent file for Audis past separator design, and possibly current too. It goes by the name of ''suction jet pump''.

http://www.freepatentsonline.com/6832603.html

It is a nice design, but, from a little r+d ive done on them, they run too cold. Reflow oil turns thick on cooling(its construction is black plastic) and gums up. If this was alloy, and bolted to head, along with drop pipe(also alloy) then Im sure this problem would vanish. These separators give a lot of trouble for this reason, I feel.

But Im not over the costing...

Brian,

 

[BrianGar]

To correct my last post, it works in tandem with the suction jet pump, they are both almost identical externally.

Brian.

 

[KevinK2]

All the Vw fsi's are n/a.

I read that the "2.0 R4 16v TFSI 125-199kW" turbo 4 is also FSI.

Here is a link to an FSI combustion chamber .. looks like the injector could wash the intake valves when the valve is open, either during intake or compression.

 

[KevinK2]

http://upload.wikimedia.org/wikipedia/commons/thumb/f/f4/3.5EcoboostCombustion.jpg/220px-

 

[KevinK2]

That link didn't work here, and it's for the ford eco-boost engine, not VW. I'll try another for Ford eco-boost chamber pic with fuel washed valves:

http://en.wikipedia.org/wiki/Gasoline_direct_injection

 

[patprimmer]

Technically, I think a dry sump that pulled a reasonable vacuum might solve the problem, however I doubt any OEM would be prepared to cough up the cost. Even a simple vacuum pump based crankcase evacuation system with a really good catch can system might do it economically

Regards
Pat
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[KevinK2]

From reviewing several current configurations for DI injector location, it appears that the main control to prevent intake valve build-up is to point the injector somewhat laterally so part of the spray cone washes the back of the valve. This means an extra injection step when the intake is near wide open.