×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

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

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

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

(OP)
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

.

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

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

Mike Halloran
Pembroke Pines, FL, USA

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

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.

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

(OP)

Quote:

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.

.  

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

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.

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

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,
 .
  

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

(OP)
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?

.  

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

(OP)
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

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

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,

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

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

Brian.

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

(OP)

Quote:

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.

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

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
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
 

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

(OP)
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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources