My question is, with all the problems with DI becoming apparent - why are more manufacturers switching to DI?
Regarding intake valve desposits with DI..
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Probably for the lower emissions, higher horsepower, and better mpg number's. Not to mention DI allowing them to run a bit higher compression on turbocharged vehicles. Of course these tests are ran on engines without enough mileage to have the dirty intake valves come into play.
Originally Posted By: shpankey
Probably for the lower emissions, higher horsepower, and better mpg number's. Not to mention DI allowing them to run a bit higher compression on turbocharged vehicles. Of course these tests are ran on engines without enough mileage to have the dirty intake valves come into play.
Granted in the beginning, but now that manufacturers know the issues with DI why continue using it without something to address the issues.
It seems to me that DI was an awesome idea, but until they change something, it's just a way for dealerships to make more money on repairs.
My 2.0t is a fun engine, but I drive the 2.5 most of the time to save me the miles.
Probably for the lower emissions, higher horsepower, and better mpg number's. Not to mention DI allowing them to run a bit higher compression on turbocharged vehicles. Of course these tests are ran on engines without enough mileage to have the dirty intake valves come into play.
Granted in the beginning, but now that manufacturers know the issues with DI why continue using it without something to address the issues.
It seems to me that DI was an awesome idea, but until they change something, it's just a way for dealerships to make more money on repairs.
My 2.0t is a fun engine, but I drive the 2.5 most of the time to save me the miles.
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MPG and power will sell them more cars. Once you have the car, they'll just bill you for carbon buildup. The Audi guys have struggled to get it covered for a while now.
Originally Posted By: dparm
MPG and power will sell them more cars. Once you have the car, they'll just bill you for carbon buildup. The Audi guys have struggled to get it covered for a while now.
Yup. I was all enthralled with direct injection. It is a selling point as it has become a big keyword expression that everyone knows.
Btw, you're right and it's an in-genius scheme!! lol
MPG and power will sell them more cars. Once you have the car, they'll just bill you for carbon buildup. The Audi guys have struggled to get it covered for a while now.
Yup. I was all enthralled with direct injection. It is a selling point as it has become a big keyword expression that everyone knows.
Btw, you're right and it's an in-genius scheme!! lol
I know, at least for the present time, and for me, that keyword expression means: Run away! Run away!
Johnny's idea of a Model A as a next car is looking better and better.
Ed
Johnny's idea of a Model A as a next car is looking better and better.
Ed
After owning a DI car, it will be my last. Even if they figure out a way to keep the buildup from happening. I have a "bad taste" from it.
Ceramic coated intake valves (or Teflon), or some other high tech non-stick coating might be one solution. Don't know if those coatings can take the pounding involved.
Originally Posted By: dwendt44
Ceramic coated intake valves (or Teflon), or some other high tech non-stick coating might be one solution. Don't know if those coatings can take the pounding involved.
The non stick on my Calphlon pans can't even stand up to cooking for over a year before it starts to come off
Ceramic coated intake valves (or Teflon), or some other high tech non-stick coating might be one solution. Don't know if those coatings can take the pounding involved.
The non stick on my Calphlon pans can't even stand up to cooking for over a year before it starts to come off
Originally Posted By: dwendt44
Ceramic coated intake valves (or Teflon), or some other high tech non-stick coating might be one solution. Don't know if those coatings can take the pounding involved.
dwent44,
FYI, VW tried a similar approach in two ways:
1) to prevent deposit accumulation using a microporous, chemically inert, and antiadhesive coating, and
2) to catalyze deposit removal via a Vanadium Nitride and Vanadium Pentoxide coating
It doesn't work unfortunately. f.e.:
Ceramic coated intake valves (or Teflon), or some other high tech non-stick coating might be one solution. Don't know if those coatings can take the pounding involved.
dwent44,
FYI, VW tried a similar approach in two ways:
1) to prevent deposit accumulation using a microporous, chemically inert, and antiadhesive coating, and
2) to catalyze deposit removal via a Vanadium Nitride and Vanadium Pentoxide coating
It doesn't work unfortunately. f.e.:
Does it slow it down though? I'd much rather clean the IM every 50k instead of every 10k.
Hmmmm, hard to say if it slows it down. It is clear though that it doesn't slow it down enough IMO. Rl_RS4's work shows noticeable accumulation in as little as 800 miles after cleaning in the 4.2 FSI.
Also under 1) above, talking about preventing deposits, I should have said "surface" rather than "coating".
Also under 1) above, talking about preventing deposits, I should have said "surface" rather than "coating".
I'm wondering if the buildup is linear or if it tends to taper off beyond a certain point. In RI_RS4's case, it may accumulate again almost immediately after a thorough cleaning but it would level off quickly and the growth would slow.
Quote:
Does it slow it down though? I'd much rather clean the IM every 50k instead of every 10k.
I'd rather not have to clean an IM ever. That might have been acceptable in 1911, now there's no excuse.
Ed
Does it slow it down though? I'd much rather clean the IM every 50k instead of every 10k.
I'd rather not have to clean an IM ever. That might have been acceptable in 1911, now there's no excuse.
Ed
My understanding is that the globular deposits encourage more deposits. A sticky first layer develops where particles can adhere, then the porous surface creates additional "binding sites" for more contaminants and so on until they become globular.
Some of Rl_RS4's photos show this pretty well as I recall. As I recall there was a 800 mile photo which suggested to me the sticky layer deposit and then a 2000 mile photo which showed the thicker deposits developing. Can't remember for sure though.
We do know that by 20k or so on some cars it can be bad enough to cause numerous problems including additional deposits on rings, spark plugs, injectors, etc. The misfiring that develops of course can damage the cat and so on.
Some of Rl_RS4's photos show this pretty well as I recall. As I recall there was a 800 mile photo which suggested to me the sticky layer deposit and then a 2000 mile photo which showed the thicker deposits developing. Can't remember for sure though.
We do know that by 20k or so on some cars it can be bad enough to cause numerous problems including additional deposits on rings, spark plugs, injectors, etc. The misfiring that develops of course can damage the cat and so on.
I believe Toyota/Lexus solved this problem by letting low pressure injectors spray a little gas on the valve like it's always been done, while still using DI for the majority of the gas charge. It seems like a very easy and reasonable solution to me.
I should invest in a scope.
Originally Posted By: glxpassat
I believe Toyota/Lexus solved this problem by letting low pressure injectors spray a little gas on the valve like it's always been done, while still using DI for the majority of the gas charge. It seems like a very easy and reasonable solution to me.
If this is the case, then yeah! we can still resort to using ordinary effective (this is the buzzword "effective" here) OTC fuel injector cleaners that contain PEA can be used here as a regular regimen to effectively keep the intake valve deposits under control.
I like this idea! sounds silly but reminds me the technical ingenuity similar to the original Honda CVCC engine design (compound vortex controlled combustion)
Q-TD
I believe Toyota/Lexus solved this problem by letting low pressure injectors spray a little gas on the valve like it's always been done, while still using DI for the majority of the gas charge. It seems like a very easy and reasonable solution to me.
If this is the case, then yeah! we can still resort to using ordinary effective (this is the buzzword "effective" here) OTC fuel injector cleaners that contain PEA can be used here as a regular regimen to effectively keep the intake valve deposits under control.
I like this idea! sounds silly but reminds me the technical ingenuity similar to the original Honda CVCC engine design (compound vortex controlled combustion)
Q-TD
This is an interesting subject, but after reading the whole thread, I haven't found an explanation for the mechanism involved in the formation of intake valve deposits. Can people out there in BITOG-land post their explanations or theories?
I remember BMW had problems with intake valve deposits and octane requirement increase in their port-injection engines in the 1990's, so this kind of problem is not unknown to port injection systems, either. That problem was due to PNA content in gasoline. This kind of problem has been overcome in the past by redesigning the intake valve so that it runs hotter and burns off the deposits. There is potentially a performance penalty when the engine is new, but the performance will not degrade over time.
I remember BMW had problems with intake valve deposits and octane requirement increase in their port-injection engines in the 1990's, so this kind of problem is not unknown to port injection systems, either. That problem was due to PNA content in gasoline. This kind of problem has been overcome in the past by redesigning the intake valve so that it runs hotter and burns off the deposits. There is potentially a performance penalty when the engine is new, but the performance will not degrade over time.
More like the '70s - BMW used a ground walnut shell blast to clean things up .
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