maybe we are lucky the new gt3 doesn't have Direct Injection...
04-07-2009, 07:17 AM
#16
Drifting
I'm no mechanic but looking at those pictures, it would seem to be due to the fact that there is no fuel in the intake chamber to help dissolve the oil vapour build up that would be present. In a conventional EFI engine, the fuel is sprayed before the valve and therefore would lubricate and help dissolve oil/carbon on its way through the valve and into the chamber where it is combusted. Harder you drive, more fuel, more build ups removed.
With the DFI engine, no fuel in the intake chamber as its sprayed directly into the cylinder, so you would get oil vapour from the recovery system sitting on the valve, heat from the other side of the valve baking it and in time, carbon build up...
With the DFI engine, no fuel in the intake chamber as its sprayed directly into the cylinder, so you would get oil vapour from the recovery system sitting on the valve, heat from the other side of the valve baking it and in time, carbon build up...
there is a few ways of fixing this problem. either have the crankcase ventilation venting to atmosphere(not advisable as you will get oil dripping out, and a oil burning smell). the other is to install a catch can. this goes in line from the crankcase vent hose and the intake manifold. it must be drained periodically too.
04-07-2009, 11:57 AM
#17
Rennlist Member
Carbon buildup- where did I hear that. The 993 had this issue and it's not even DI. I hate to imagine what di could do on the gt1 motor. Expensive repair. If so hopefully they will have a fix. mike
04-07-2009, 12:40 PM
#18
Three Wheelin'
bingo. all engines have a little blow-by of some sort, on all cars this blow by exits the engine via crankcase ventilation, in this day and age because of environmental concerns blow by is pushed back into the intake system to be burned by the combustion process. this covers the whole intake system in oil vapour. in normal petrol engines this oil is washed off the intake tract via the fuel from the injectors. depending on the quality of fuel, will be dependent of how good the valves are kept clean.(cheap nasty fuels don't clean as good as Hi octane quality fuel)
there is a few ways of fixing this problem. either have the crankcase ventilation venting to atmosphere(not advisable as you will get oil dripping out, and a oil burning smell). the other is to install a catch can. this goes in line from the crankcase vent hose and the intake manifold. it must be drained periodically too.
there is a few ways of fixing this problem. either have the crankcase ventilation venting to atmosphere(not advisable as you will get oil dripping out, and a oil burning smell). the other is to install a catch can. this goes in line from the crankcase vent hose and the intake manifold. it must be drained periodically too.
BTW, great info (along with the LSD) again guys!
04-07-2009, 02:02 PM
#19
bingo. all engines have a little blow-by of some sort, on all cars this blow by exits the engine via crankcase ventilation, in this day and age because of environmental concerns blow by is pushed back into the intake system to be burned by the combustion process. this covers the whole intake system in oil vapour. in normal petrol engines this oil is washed off the intake tract via the fuel from the injectors. depending on the quality of fuel, will be dependent of how good the valves are kept clean.(cheap nasty fuels don't clean as good as Hi octane quality fuel)
there is a few ways of fixing this problem. either have the crankcase ventilation venting to atmosphere(not advisable as you will get oil dripping out, and a oil burning smell). the other is to install a catch can. this goes in line from the crankcase vent hose and the intake manifold. it must be drained periodically too.
there is a few ways of fixing this problem. either have the crankcase ventilation venting to atmosphere(not advisable as you will get oil dripping out, and a oil burning smell). the other is to install a catch can. this goes in line from the crankcase vent hose and the intake manifold. it must be drained periodically too.
I've read various -- polarized -- opinions on "good" versus "cheap" gas. The additives in some branded fuels were variously tested and found to be irrelevant. I put in a bottle of Techron additive before each oil change ... this is an old 993 practice which, as far as I know, is documented in the service manuals, but I dunno. : )
04-07-2009, 03:48 PM
#20
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You guys have pretty much nailed the cause as far as I've been told. As for solutions, some have suggested a bluetec-like spray to clean up the deposits. I really have no idea how feasible or effective this would be.
Not to add more fuel to the fire but DI engines are also known to dilute the oil. Many people from the Audi boards send their oil for analysis (Dyson labs I believe). Almost all of the reports have shown significant oil degradation.
Not to add more fuel to the fire but DI engines are also known to dilute the oil. Many people from the Audi boards send their oil for analysis (Dyson labs I believe). Almost all of the reports have shown significant oil degradation.
04-07-2009, 03:51 PM
#21
Nordschleife Master
Another reason to change oil more often.
04-07-2009, 04:48 PM
#22
Rennlist Member
You guys have pretty much nailed the cause as far as I've been told. As for solutions, some have suggested a bluetec-like spray to clean up the deposits. I really have no idea how feasible or effective this would be.
Not to add more fuel to the fire but DI engines are also known to dilute the oil. Many people from the Audi boards send their oil for analysis (Dyson labs I believe). Almost all of the reports have shown significant oil degradation.
Not to add more fuel to the fire but DI engines are also known to dilute the oil. Many people from the Audi boards send their oil for analysis (Dyson labs I believe). Almost all of the reports have shown significant oil degradation.
Peter
04-07-2009, 05:12 PM
#23
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Not to add more fuel to the fire but DI engines are also known to dilute the oil. Many people from the Audi boards send their oil for analysis (Dyson labs I believe). Almost all of the reports have shown significant oil degradation.
Regards,
04-07-2009, 09:36 PM
#24
Nordschleife Master
Would Seafoam or Gunk Valve Medic be safe on these engines?
04-07-2009, 09:55 PM
#25
GT3 player par excellence
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dont worry, the germans usually will get it right after 20+ years.
my 2025 GTx will be fine with DFI
my 2025 GTx will be fine with DFI
04-08-2009, 12:03 AM
#26
Nordschleife Master
I talked to many contacts in the Porsche world and here is a summary of what I gathered:
The DFI engine brings a set of issues to deal with. These are just there and they are not necessarily game-stoppers. Understanding them is important. The following are procedures that should be followed w/ these engines:
1 - Avoid short trips. Always allow proper oil operating temp and temp cycle.
2 - Change oil more frequently - perhaps 5-6k miles. (15k oil changes were insane anyway)
3 - Do a 15k miles (or yearly) intake clean service using an appropriate intake cleaner product.
Hopefully, abiding by these rules, these engines will last and be trouble free.
The DFI engine brings a set of issues to deal with. These are just there and they are not necessarily game-stoppers. Understanding them is important. The following are procedures that should be followed w/ these engines:
1 - Avoid short trips. Always allow proper oil operating temp and temp cycle.
2 - Change oil more frequently - perhaps 5-6k miles. (15k oil changes were insane anyway)
3 - Do a 15k miles (or yearly) intake clean service using an appropriate intake cleaner product.
Hopefully, abiding by these rules, these engines will last and be trouble free.
04-22-2009, 04:34 PM
#28
Rennlist Member
In any case, looks like just one more reason to stick with my crude, antique air cooled stuff that I can actually fix myself, and not break the bank while doing so.
04-22-2009, 05:30 PM
#29
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Maybe the RMS issue is really Porsche's early attempt to force you to keep adding new oil to the car so that you are accustom to this process prior to the introduction of the DI when you must have it changed more often? There really is no plan to fix the RMS. It was never broken. It took them 5 years to engineer it that way. Sneaky those Germans.
04-22-2009, 07:38 PM
#30
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I talked to many contacts in the Porsche world and here is a summary of what I gathered:
The DFI engine brings a set of issues to deal with. These are just there and they are not necessarily game-stoppers. Understanding them is important. The following are procedures that should be followed w/ these engines:
1 - Avoid short trips. Always allow proper oil operating temp and temp cycle.
2 - Change oil more frequently - perhaps 5-6k miles. (15k oil changes were insane anyway)
3 - Do a 15k miles (or yearly) intake clean service using an appropriate intake cleaner product.
Hopefully, abiding by these rules, these engines will last and be trouble free.
The DFI engine brings a set of issues to deal with. These are just there and they are not necessarily game-stoppers. Understanding them is important. The following are procedures that should be followed w/ these engines:
1 - Avoid short trips. Always allow proper oil operating temp and temp cycle.
2 - Change oil more frequently - perhaps 5-6k miles. (15k oil changes were insane anyway)
3 - Do a 15k miles (or yearly) intake clean service using an appropriate intake cleaner product.
Hopefully, abiding by these rules, these engines will last and be trouble free.
these were the same bull crap they told my dad and uncle decades ago BEFORE DFI. i am certain these gospel will continue to be the norm in the year 3085 when we ( i mean our AI robotic servants ) all drive clean, fusion powered, DFiQTA, 9 wheel drive, PDK-102 (400 speed) gearbox, hermetially healed tungsten titanium RMS, intergalactic transport with porsche logos.
but that's all cool though, b/c i be VERY OLD then. i dont want to learn any new tricks. just keep driving longer trips, oil change 5-6000 miles and service intake with what chevron makes then.... i can remember three basic axioms....