Adamw Posted October 4, 2016 Report Share Posted October 4, 2016 Hi guys Wondered what the consenseous was for fuelling 2.7 986's? Ie 95 or 98 ron I understand ideally 98 is better (obviously) but I'm considering using my current Boxster as a daily commute covering 250 miles a week so obviously there would be a differing price between 95 & 98... I don't want to use 95 to the detriment of the car so really looking for honest opinions on if the car could alternate between the two fuel grades without causing any issues ? Cheers in advance guys Adam Link to comment Share on other sites More sharing options...
bagss2 Posted October 4, 2016 Report Share Posted October 4, 2016 Look inside the fuel flap and put in whatever RON it states... My 986S is 98 and I feed it Shell V-Power (or whatever it's called this week). Cheers, Baggers. Link to comment Share on other sites More sharing options...
PaulQ Posted October 4, 2016 Report Share Posted October 4, 2016 If you want to use 95 RON then do. It will run just fine Link to comment Share on other sites More sharing options...
cj225 Posted October 4, 2016 Report Share Posted October 4, 2016 I find mine runs a bit lumpy on normal stuff, so I tend to stick to V Power. Most pumps don't even give you the octane these days Link to comment Share on other sites More sharing options...
Menoporsche Posted October 5, 2016 Report Share Posted October 5, 2016 12 hours ago, Adamw said: really looking for honest opinions on if the car could alternate between the two fuel grades without causing any issues ? I think you can but there isn't much point. Isn't it that the ECU learns and then adapts settings accordingly - each time you put a different fuel in, there's fifty miles or more of learning before it adapts? Link to comment Share on other sites More sharing options...
cj225 Posted October 5, 2016 Report Share Posted October 5, 2016 The difference in price is quite negligible anyway over a full tank, I found. 5p per litre difference is only about £2 across a full tank (top of my head maths), so it's not really the best area for improvement. You'd be better served to change your driving style/speed and keep the better fuel Link to comment Share on other sites More sharing options...
Jon61 Posted October 5, 2016 Report Share Posted October 5, 2016 35 minutes ago, Menoporsche said: I think you can but there isn't much point. Isn't it that the ECU learns and then adapts settings accordingly - each time you put a different fuel in, there's fifty miles or more of learning before it adapts? I am far from an expert on these things, but I don't think the ECU adapting to a different octane fuel is like a PDK gearbox 'learning' a different driving style over a number of miles. My understanding is that it uses the feedback from the various sensors (particularly the knock sensor) and adjusts the engine timing pretty much instantly (ie for the next cycle). So you can switch back and forth without any trouble whatsoever. (This part of the ECU is more like a chicken's brain than a chimpanzee's!) IIRC, all Porsche say is that the engines are designed for best performance and fuel economy to run on 98, but will adapt if you put 95 in. And I think they just say that fuel economy will be worse if you use lower than 95 (which you can even do in an emergency). I don't believe it will do the slightest damage to your engine if you only ever use 95, or if you switch between the two. Frankly, I doubt you will notice the difference in performance in road driving and I don't even know about fuel economy - I think several people on here have tried measuring it over long periods (but not in laboratory conditions!) and have had differing results. IMHO anyone whose engine seems not to run properly on decent quality 95 either has a fault, or is imagining it Link to comment Share on other sites More sharing options...
cj225 Posted October 5, 2016 Report Share Posted October 5, 2016 29 minutes ago, Jon61 said: I am far from an expert on these things, but I don't think the ECU adapting to a different octane fuel is like a PDK gearbox 'learning' a different driving style over a number of miles. My understanding is that it uses the feedback from the various sensors (particularly the knock sensor) and adjusts the engine timing pretty much instantly (ie for the next cycle). So you can switch back and forth without any trouble whatsoever. (This part of the ECU is more like a chicken's brain than a chimpanzee's!) IIRC, all Porsche say is that the engines are designed for best performance and fuel economy to run on 98, but will adapt if you put 95 in. And I think they just say that fuel economy will be worse if you use lower than 95 (which you can even do in an emergency). I don't believe it will do the slightest damage to your engine if you only ever use 95, or if you switch between the two. Frankly, I doubt you will notice the difference in performance in road driving and I don't even know about fuel economy - I think several people on here have tried measuring it over long periods (but not in laboratory conditions!) and have had differing results. IMHO anyone whose engine seems not to run properly on decent quality 95 either has a fault, or is imagining it It's not that quick to adapt on older cars (986 inclusive), and could be different on more modern ECUs. The 986 in particular needs to measure over a specific number of cycles before it will amend the fuelling. Link to comment Share on other sites More sharing options...
Bike Loon Posted October 5, 2016 Report Share Posted October 5, 2016 I really should stop being cheap and putting 95ron in my 987S ? Link to comment Share on other sites More sharing options...
ooid Posted October 5, 2016 Report Share Posted October 5, 2016 I can not find the written source now but there has been a highly spoken case about using 95 or worse fuels on m96/m97 engines in addition to lack of oil changes was also causing early engines failures. Not being the expert on engines in terms of fuel quality, I've always used 98(shell v-power) on my 986, considering the fact that car is over than 15 years old, and not driven super daily anyway. Link to comment Share on other sites More sharing options...
Menoporsche Posted October 5, 2016 Report Share Posted October 5, 2016 Fuels? Always thought it was (alledgedly) the oil viscosity. Link to comment Share on other sites More sharing options...
Adamw Posted October 6, 2016 Author Report Share Posted October 6, 2016 Thanks for all the comments guys Based on opinions it seems that for the relatively little price difference each tank and as its 98 ron Porsche recommends I'll stick with the 98 ron good stuff.. Just out of interest what sort MPG is realistic on a 2.7 986. Understand driving style and journey makes a difference. I do 50 miles a day in round trip to work with some fast A roads and some stop/start commute conditions as in near the office. Currently seeing 22.0 Mpg ?? Link to comment Share on other sites More sharing options...
RBD914 v2 Posted October 6, 2016 Report Share Posted October 6, 2016 22mpg seems very low to me? Would expect high twenties. Link to comment Share on other sites More sharing options...
Jason986S Posted October 6, 2016 Report Share Posted October 6, 2016 I see low 20's around town and about 30 on the motorway (3.2 986S). If giving it stick on B-roads it can drop down to low teens too. Link to comment Share on other sites More sharing options...
fischer Posted October 6, 2016 Report Share Posted October 6, 2016 2 hours ago, RBD914 v2 said: 22mpg seems very low to me? Would expect high twenties. Agree with this, I still can not believe how well these cars do on MPG even when driving with a heavy foot. Link to comment Share on other sites More sharing options...
Adamw Posted October 6, 2016 Author Report Share Posted October 6, 2016 Ok I also felt that 22mpg was low and I used to have a 986S and think that was better. My former 993 C4 air-cooled car used to be similar so sure the Box should be better. This is a new car (to me) and it didn't really get used much the previous owner and it used to sit around allot for long periods. The mpg fugure is gradually working its way up the more I use it. Was on 20 when I 1st dove home last Sat and now at 23mpg. Could the lack of use or maybe differnent use previously (short stop/start journeys) have an impact on why the MPG is reading so low. Im not particularly driving with a lead foot now either. Any suggestions for possible causes for low MPG / over fueling. IE faulty sensors etc? Cheers in advance Adam Link to comment Share on other sites More sharing options...
Jason986S Posted October 6, 2016 Report Share Posted October 6, 2016 Is it due a good service? Maybe also get the lambda's and emissions tested? Give the coil packs a visual inspection, and possibly considering cleaning the MAF and Throttle Body. Link to comment Share on other sites More sharing options...
RBD914 v2 Posted October 6, 2016 Report Share Posted October 6, 2016 Short journeys would do it, mine only does low twenties until it has done 30 miles or so then averages 28 mpg or thereabouts. It seems they are more efficient once warmed up! Link to comment Share on other sites More sharing options...
Adamw Posted October 6, 2016 Author Report Share Posted October 6, 2016 6 hours ago, Jason986S said: Is it due a good service? Maybe also get the lambda's and emissions tested? Give the coil packs a visual inspection, and possibly considering cleaning the MAF and Throttle Body. It is due a good service. It's about on 12k and it's been over a year. Booked in for next Fri when it will get new oil and a good check over. Just before my ownership (bought off a friend) it threw the engine management light in the way to get mot'd. This was after the car had been stood for a month or so outside. The MOT station plugged in thier OBD and it advised of a faulty coil on cylinder 5 which was triggering O2 sensor faults. We were advised that coils can sometimes build up moisture if the car is left stood for too long and these can sometimes dry out/clear after some good use. The error was reset and I hoped that would be that but wondering is this could be related. Other symptoms : -Lumpy at very low rev (under 1000) -wobbly idle - very occasionally mifires / Almost feels like over/fuelling? - sometimes feels very flat up to 3k and sometimes its more urgent. Going to have coils checked on service as this is what the OBD reported (cylinder 5) Questions: 1/ Does this sound like a coil problem or something more? 2/ Could this this be related to low MPG? Cheers again guys Adam Link to comment Share on other sites More sharing options...
mavis.d Posted October 6, 2016 Report Share Posted October 6, 2016 I've had mine for 2 1/2 years and run most of the time on Shell Vmax. I drive very much in the sprit of the car ? Ave 26 best 34 and worst 21. Done about 24k Link to comment Share on other sites More sharing options...
Menoporsche Posted October 6, 2016 Report Share Posted October 6, 2016 Adam - an Italian tune-up down a motorway and A-roads is in order! Link to comment Share on other sites More sharing options...
Adamw Posted October 6, 2016 Author Report Share Posted October 6, 2016 5 minutes ago, Menoporsche said: Adam - an Italian tune-up down a motorway and A-roads is in order! Tried some "Italian tuning" over the last 150 miles but no difference I'm afraid .., Link to comment Share on other sites More sharing options...
moneypit Posted October 6, 2016 Report Share Posted October 6, 2016 I've noticed that my stuff tends to get better mpg on higher octane fuel, which would suggest that it's better quality. And hence worth the effort. A Porsche is meant to be a high quality item, if it goes further per gallon on the better stuff, it isn't costing anything extra to use it. Link to comment Share on other sites More sharing options...
Jason986S Posted October 6, 2016 Report Share Posted October 6, 2016 1 hour ago, Adamw said: It is due a good service. It's about on 12k and it's been over a year. Booked in for next Fri when it will get new oil and a good check over. Just before my ownership (bought off a friend) it threw the engine management light in the way to get mot'd. This was after the car had been stood for a month or so outside. The MOT station plugged in thier OBD and it advised of a faulty coil on cylinder 5 which was triggering O2 sensor faults. We were advised that coils can sometimes build up moisture if the car is left stood for too long and these can sometimes dry out/clear after some good use. The error was reset and I hoped that would be that but wondering is this could be related. Other symptoms : -Lumpy at very low rev (under 1000) -wobbly idle - very occasionally mifires / Almost feels like over/fuelling? - sometimes feels very flat up to 3k and sometimes its more urgent. Going to have coils checked on service as this is what the OBD reported (cylinder 5) Questions: 1/ Does this sound like a coil problem or something more? 2/ Could this this be related to low MPG? Cheers again guys Adam Based on that lot, I would give the plugs/coils a good once over and strongly consider replacing. They're not hugely expensive in the grand scale. Lambda's are a bit more money (x4) so guess it's logical to do the cheaper service items first. Link to comment Share on other sites More sharing options...
Adamw Posted October 6, 2016 Author Report Share Posted October 6, 2016 4 minutes ago, Jason986S said: Based on that lot, I would give the plugs/coils a good once over and strongly consider replacing. They're not hugely expensive in the grand scale. Lambda's are a bit more money (x4) so guess it's logical to do the cheaper service items first. Thanks !! I've got record in the history that plugs were changed last year so hopefully just coils. Any known deals\places to buy from? Beru or OEM? Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.