NAGTROC.com discuss DI (Direct Injection)
04-27-10 | 07:45 AM
#1
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NAGTROC.com discuss DI (Direct Injection)
http://www.nagtroc.org/forums/index....pic=39598&st=0
Saw this over on NAGTROC.com showing what problems AUDI and LEXUS have had with DI? I saw them talking about the IS-F and saying this was it's big hold back and mistake that Lexus made? Can anyone here on the baord shed some light on this if there is any truth to what they are saying? So far looks like DI causes horrible carbon build up.....
Ryan,
Saw this over on NAGTROC.com showing what problems AUDI and LEXUS have had with DI? I saw them talking about the IS-F and saying this was it's big hold back and mistake that Lexus made? Can anyone here on the baord shed some light on this if there is any truth to what they are saying? So far looks like DI causes horrible carbon build up.....
Ryan,
04-27-10 | 08:19 AM
#2
http://www.nagtroc.org/forums/index....pic=39598&st=0
Saw this over on NAGTROC.com showing what problems AUDI and LEXUS have had with DI? I saw them talking about the IS-F and saying this was it's big hold back and mistake that Lexus made? Can anyone here on the baord shed some light on this if there is any truth to what they are saying? So far looks like DI causes horrible carbon build up.....
Ryan,
Saw this over on NAGTROC.com showing what problems AUDI and LEXUS have had with DI? I saw them talking about the IS-F and saying this was it's big hold back and mistake that Lexus made? Can anyone here on the baord shed some light on this if there is any truth to what they are saying? So far looks like DI causes horrible carbon build up.....
Ryan,
04-27-10 | 09:37 AM
#4
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This has also been discussed exhaustively here:
http://www.6speedonline.com/forums/9...ine-issue.html
That thread also links to another. I notice that the same pictures are linked in the NAGTROC post. Here's a good summary from the OP at 6spd:
http://www.6speedonline.com/forums/9...ine-issue.html
That thread also links to another. I notice that the same pictures are linked in the NAGTROC post. Here's a good summary from the OP at 6spd:
Originally Posted by adias
I started this thread for discussion and information. I also 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. (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. (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.
04-27-10 | 09:40 AM
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I was at the Lexus dealership about 9 months ago or so getting some oil change parts and the parts counter guy was telling me about this as well. Said it was or could be an issue for direct injection only, not those with both direct and port injection as in the IS-F and IS350. IS250 on the other hand could be a problem down the road.
Originally Posted by Ian_UK1
This is absolutely inevitable with DFI engines.
The backs of the inlet valves on conventional fuel injection engines are both cooled by the injected fuel and kept clean by the detergent and other additives in the fuel. This simply does not happen with a DFI engine as the fuel is injected directly into the combustion chamber (i.e. on the other side of the valve). This means oil from the valve guides will inevitably get on the back of the (now much hotter) valve, not be washed away by the fuel and in short-order gunk eveything up as in the picture.
This will cause the performance of DFI engines to drop away noticeably and quickly with age as the inlet valves will be less able to pass air into the engine. It is also only able to be cured by substantial re-engineering of the inlet valve guide oiling system (effectively a new cylinder head design) that seals the inlet ports from the oil. Not something I can imagine Porsche paying for....
The backs of the inlet valves on conventional fuel injection engines are both cooled by the injected fuel and kept clean by the detergent and other additives in the fuel. This simply does not happen with a DFI engine as the fuel is injected directly into the combustion chamber (i.e. on the other side of the valve). This means oil from the valve guides will inevitably get on the back of the (now much hotter) valve, not be washed away by the fuel and in short-order gunk eveything up as in the picture.
This will cause the performance of DFI engines to drop away noticeably and quickly with age as the inlet valves will be less able to pass air into the engine. It is also only able to be cured by substantial re-engineering of the inlet valve guide oiling system (effectively a new cylinder head design) that seals the inlet ports from the oil. Not something I can imagine Porsche paying for....
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04-27-10 | 11:40 AM
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there's only one way to know for sure or not, and that's to open the head up and have a look see.
I somehow doubt the ISF will have the same level of carbon as the RS4, on which it is endemic and serious.
Toyota engineers their engines to last 130k miles, no matter what. I am quite sure they took this into account, as I know german engineers were aware of the carbon build up scenario, it was not a surprise as some thought on NAGTROC.
I somehow doubt the ISF will have the same level of carbon as the RS4, on which it is endemic and serious.
Toyota engineers their engines to last 130k miles, no matter what. I am quite sure they took this into account, as I know german engineers were aware of the carbon build up scenario, it was not a surprise as some thought on NAGTROC.
04-27-10 | 11:41 AM
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04-27-10 | 12:08 PM
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there's only one way to know for sure or not, and that's to open the head up and have a look see.
I somehow doubt the ISF will have the same level of carbon as the RS4, on which it is endemic and serious.
Toyota engineers their engines to last 130k miles, no matter what. I am quite sure they took this into account, as I know german engineers were aware of the carbon build up scenario, it was not a surprise as some thought on NAGTROC.
I somehow doubt the ISF will have the same level of carbon as the RS4, on which it is endemic and serious.
Toyota engineers their engines to last 130k miles, no matter what. I am quite sure they took this into account, as I know german engineers were aware of the carbon build up scenario, it was not a surprise as some thought on NAGTROC.
https://www.clublexus.com/forums/is-...-build-up.html
04-27-10 | 12:13 PM
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You're right, the IS-F likely won't suffer like the RS4 did, but what about the IS250? In the IS lineup, the 4GR-FSE engine is the only one without both DI and port injection. It is DI only.
https://www.clublexus.com/forums/is-...-build-up.html
https://www.clublexus.com/forums/is-...-build-up.html
With the RS4 it was very noticeable, power was down a lot, and most horrible is that it afflicted many people's cars.
Mind you with the horror stories of the RS4, some guys were having issues as early as 20k or less !! Miles. Guy from australia had about that mileage and his valves were absolutely covered in gunk..
I used to have an S4 and spent a lot of time on the audi pages. Frequent oil changes, advanced cleaners, high quality fuel (which was greatly debated) , none of those helped at all in reducing the valve deposits.
If the IS you mentioned has issues, Im sure they would have reared their head by now?
Last edited by Ekorre; 04-27-10 at 12:16 PM.
04-27-10 | 12:17 PM
#14
There has been some talk of the 250's suffering the common DI-only issues - fuel in the oil, carbon build up, power loss, and rough idling. If I owned one, I'd put water injection on it to prevent all this from happening in the first place.
I doubt the F really needs it since the port injectors are working at mid-range rpm and light throttle, so there's not a lot of opportunity for build up in the 2UR-GSE where I would expect carbon problems in the 4GR-FE.
I doubt the F really needs it since the port injectors are working at mid-range rpm and light throttle, so there's not a lot of opportunity for build up in the 2UR-GSE where I would expect carbon problems in the 4GR-FE.
