Intake deposits in direct-injected Minis...

[d00df00d]

My brother is friends with the shop foreman at a local Mini dealer. He went down there to hang out and saw some pretty interesting things that I thought I'd share, as they seem relevant to the ongoing discussion about fuel dilution and intake system deposits in direct-injected engines. If any of this is old news, feel free to ignore me.

Several of the new direct-injected engines were apart for service. They had a variety of things wrong with them, but all of them had significant intake valve deposits. Many were low mileage engines. Apparently they looked just like what we are seeing in VW engines.

Here's the kicker. My brother heard that Mini is going to re-fit the intake manifolds on those cars, adding nozzles to the runners right next to where they bolt to the head. Some kind of device will be able to attach to those nozzles to clean the intake valve deposits. I'm not sure if it's going to facilitate dealer service, or if the system will be permanently installed in the car.

Anyway, there's an anecdote FWIW. If it's true, it sounds interesting...

 

[Eddie]

Yes it does sound interesting. My CX7 DISI engine

 

[saaber1]

Great info. So we now have confirmation of valve deposits in direct injections engines from Mini (Peugeot), BMW, Porsche, VW, Audi.

Lots of guys have been using Meth/water injection in the 2.0 FSI for power gains but it also does help with deposits. It deosn't solve the problem, but it helps. Also, TOyota using a seperate fuel injector in the manifold which seems to solve the problem. I think that is what all manufacturers should do.

 

[d00df00d]

Originally Posted By: saaber1
TOyota using a seperate fuel injector in the manifold which seems to solve the problem. I think that is what all manufacturers should do.

If this does indeed solve the problem, I agree wholeheartedly. I wonder what the downside is if they are the only one doing this...

 

[Nederlander75]

If the Ester based oils like RLI and RL are able to keep clean wouldnt these vapors also clean up the intake/valves over time as the oil vapor recondences?

 

[d00df00d]

Originally Posted By: Nederlander75
If the Ester based oils like RLI and RL are able to keep clean wouldnt these vapors also clean up the intake/valves over time as the oil vapor recondences?

I would imagine that the esters in those oils are actually among the least volatile components, so any oil vapors will have very little ester content.

What vapors certainly do contain are a lot of volatile by-products, especially when there is a lot of fuel dilution. These are actually what cause deposits.

 

[UG_Passat]

Originally Posted By: d00df00d
Originally Posted By: saaber1
TOyota using a seperate fuel injector in the manifold which seems to solve the problem. I think that is what all manufacturers should do.

If this does indeed solve the problem, I agree wholeheartedly. I wonder what the downside is if they are the only one doing this...


Not all Toyota D4 setups are like this. The older D4's are direct injection only. The newer D4S are combo port/direct injection, ie Lexus IS350 engine.

 

[saaber1]

Originally Posted By: d00df00d
What vapors certainly do contain are a lot of volatile by-products, especially when there is a lot of fuel dilution. These are actually what cause deposits.


Right, it is ironic that the only "agents" available to the valves to do the cleaning are the same ones that cause the deposits!

I would like to hear more from Rl-RS4 on exactly how Biosyn benefits the valve deposit issue, but I would hazard a guess that low volatility and polar ester base are probably key components.? But to really understand it we need to know precisely what is present in the crankcase gasses (beside water and fuel, of course). I posted an article a long time ago on BITOG about crankcase gas composition. I'll see if I can dig it up.

 

[d00df00d]

IIRC, they were saying it's a combination of:

- Very low volatility
- VERY high starting flash point
- Better piston ring sealing
- Reduced tendency for gasoline to mix with it

Basically, it works by preventing intake system deposits instead of cleaning them (which would be impossible for an engine oil).

 

[Nederlander75]

Ah, my mistake. I assumed the esters would be evaporating with everything else. RLI is one of the worst from what I see on their data sheets of the niche synthetics with regard to posted NOAK. So, if Shell's nitrogen enriched fuels do what they are advertised the cleaning agents will hit the valves as the vapor is reconstituted.

 

[d00df00d]

Doesn't RLI list a "less than xx" value for volatility?

 

[Nederlander75]

Only on their HTHS #s.

 

[glxpassat]

Originally Posted By: saaber1
TOyota using a seperate fuel injector in the manifold which seems to solve the problem. I think that is what all manufacturers should do.


Good grief, if you have to do that, why have DI at all? Just go back to the good ole tried and true fuel injection and forget DI! I just don't see any benefits to DI...

 

[d00df00d]

Originally Posted By: glxpassat
Good grief, if you have to do that, why have DI at all? Just go back to the good ole tried and true fuel injection and forget DI! I just don't see any benefits to DI...

DI still lets manufacturers eke out more power and fuel economy.

As far as I'm concerned, it would never have been rushed to market if cars were simply lighter. But that's a whole 'nother can of worms...

 

[Steve S]

Originally Posted By: d00df00d
Doesn't RLI list a "less than xx" value for volatility?
There is always blow by to deal with untill a 100% piston ring to cyl wall seal under conbustion pressures.

 

[MCompact]

Originally Posted By: saaber1
Great info. So we now have confirmation of valve deposits in direct injections engines from Mini (Peugeot), BMW, Porsche, VW, Audi.

Lots of guys have been using Meth/water injection in the 2.0 FSI for power gains but it also does help with deposits. It deosn't solve the problem, but it helps. Also, TOyota using a seperate fuel injector in the manifold which seems to solve the problem. I think that is what all manufacturers should do.


Don't forget Mazda...

 

[Silk]

Didn't anyone learn from Mitsubishi and the GDI? Nothing wrong with direct injection - it's the EGR causing the problem.

 

[saaber1]

Originally Posted By: Silk
Didn't anyone learn from Mitsubishi and the GDI? Nothing wrong with direct injection - it's the EGR causing the problem.


Right, that is why on the list of solutions/treatment options posted on this page https://bobistheoilguy.com/forums/threads/bmw-135i-oil-issue.113699/, only 3 were identified as solving the problem rather that treating symptoms.

Those 3 solutions eliminate the pcv/EGR return to the intake.