Andy9376 Posted February 24, 2020 Report Share Posted February 24, 2020 Morning My 987 seems to be using more fuel than normal. Any suggestions as to the likely causes? Thanks Link to comment Share on other sites More sharing options...
Pinewood Posted February 24, 2020 Report Share Posted February 24, 2020 Tyre pressures Link to comment Share on other sites More sharing options...
Topbox Posted February 24, 2020 Report Share Posted February 24, 2020 Your are enjoying it more? Link to comment Share on other sites More sharing options...
antjrice Posted February 24, 2020 Report Share Posted February 24, 2020 6 minutes ago, Pinewood said: Tyre pressures That's an interesting point as you'd have to swap my tyres for tank tracks before I realized a difference on account of my spirited mood on any given drive affecting my fuel economy more that anything else. How much of a variation have you detected? Link to comment Share on other sites More sharing options...
Mattman42 Posted February 24, 2020 Report Share Posted February 24, 2020 colder mornings - longer running on choke? no idea, just a guess Link to comment Share on other sites More sharing options...
Menoporsche Posted February 24, 2020 Report Share Posted February 24, 2020 Would a damaged MAF do this? Something that tells the engine there is too much air so it needs to put in more fuel to compensate? Or air hose leak somewhere? I'm not great at all this modern sensor malarky (oh those days of feeler gauges for points) but I could imagine something like that. Link to comment Share on other sites More sharing options...
Boxob Posted February 24, 2020 Report Share Posted February 24, 2020 Certainly a failing MAF can adversely affect MPG but I'd look elsewhere first as per the suggestions above. Link to comment Share on other sites More sharing options...
NutsyH Posted February 24, 2020 Report Share Posted February 24, 2020 Enthusiastic right foot Too long in Sport + Link to comment Share on other sites More sharing options...
Pinewood Posted February 24, 2020 Report Share Posted February 24, 2020 7 hours ago, antjrice said: That's an interesting point as you'd have to swap my tyres for tank tracks before I realized a difference on account of my spirited mood on any given drive affecting my fuel economy more that anything else. How much of a variation have you detected? I check my fleet every 2-3 weeks so can't say have noticed any higher than usual fuel readings. The diesel X3 3.0d gives me 36mpg no mater how I drive and the Porsche, well.... What's mpg? The town Golf always high 30's unless the kids (young adults) get hold of it Link to comment Share on other sites More sharing options...
Nobbie Posted February 24, 2020 Report Share Posted February 24, 2020 Worth checking your exhaust and bumper around for signs of soot. Can be a sign of overfueling due to a sensor issue or faulty injector. Link to comment Share on other sites More sharing options...
Andy9376 Posted February 24, 2020 Author Report Share Posted February 24, 2020 Thanks a lot for the replies all. It’s probably doing around 60 miles less on a full tank. I did have a new tyre fitted two weeks ago too. Link to comment Share on other sites More sharing options...
Paul P Posted February 24, 2020 Report Share Posted February 24, 2020 1 hour ago, Andy9376 said: Thanks a lot for the replies all. It’s probably doing around 60 miles less on a full tank. I did have a new tyre fitted two weeks ago too. Brakes binding ? Gentle run around the block, are all the wheels the same temp ? Link to comment Share on other sites More sharing options...
sa utah Posted February 24, 2020 Report Share Posted February 24, 2020 I think what would be great was a list of let’s say reference values for live data. I have this for our M3 so can see if anything is going wrong or has failed nominal long term fuel trims O2 voltages etc I can read those values with my cheap obd2 and the Car Scanner app but I don’t really know what the values should be. be great to get some nominal readings to compare to. Link to comment Share on other sites More sharing options...
Mattman42 Posted February 24, 2020 Report Share Posted February 24, 2020 i must admit i don't think i'd notice a 60 mile variation i tend to just fill it when the light comes on Link to comment Share on other sites More sharing options...
Andy9376 Posted February 24, 2020 Author Report Share Posted February 24, 2020 1 hour ago, Paul P said: Brakes binding ? Gentle run around the block, are all the wheels the same temp ? I’ll check that, thanks a lot Link to comment Share on other sites More sharing options...
DaveEFI Posted February 25, 2020 Report Share Posted February 25, 2020 Mine does do worse MPG in cold weather. Used every day, so not just for long journeys. Think the fact they take longer than many cars to warm up doesn't help. Link to comment Share on other sites More sharing options...
petemac Posted February 25, 2020 Report Share Posted February 25, 2020 If it's a high mileage car could be several things I would also look at: Plugs-Fuel injectors-Bad o2 sensors. Link to comment Share on other sites More sharing options...
petemac Posted February 25, 2020 Report Share Posted February 25, 2020 Forgot to ask does it feel like it's running ok with no hesitation etc ? Link to comment Share on other sites More sharing options...
Andy9376 Posted February 25, 2020 Author Report Share Posted February 25, 2020 10 hours ago, petemac said: Forgot to ask does it feel like it's running ok with no hesitation etc ? Yeah it seems fine in terms of how it’s running. Link to comment Share on other sites More sharing options...
Andy9376 Posted February 25, 2020 Author Report Share Posted February 25, 2020 11 hours ago, DaveEFI said: Mine does do worse MPG in cold weather. Used every day, so not just for long journeys. Think the fact they take longer than many cars to warm up doesn't help. I did wonder but I’ve never encountered it in previous winters. Link to comment Share on other sites More sharing options...
Boxob Posted February 25, 2020 Report Share Posted February 25, 2020 20 minutes ago, Andy9376 said: Yeah it seems fine in terms of how it’s running. Unlikely to be the MAF then. Link to comment Share on other sites More sharing options...
DaveEFI Posted February 26, 2020 Report Share Posted February 26, 2020 13 hours ago, Andy9376 said: I did wonder but I’ve never encountered it in previous winters. I only ever fill up when near empty, and then brim it. And zero the MPG reader. Only been used around London in the winter, and get 15.7 mpg. 3.4S PDK. Link to comment Share on other sites More sharing options...
Andy9376 Posted February 26, 2020 Author Report Share Posted February 26, 2020 I don’t actually track MPG but I do very similar routes in my car and had it years, so it does seem a bit odd. It’s been like it for 3 fill ups in a row now. Link to comment Share on other sites More sharing options...
zcacogp Posted February 26, 2020 Report Share Posted February 26, 2020 Tracking MPG is a good idea but you need to do it for a long period of time to make any meaningful conclusions. Logging the type of journeys done since fill-up is also necessary as cars will do better on longer trips. And an accurate MPG measure is always brim-to-brim when filling; don't rely on the instruments in the car as you have no way of knowing how accurate they are. FWIW I did this for a number of years with my old car (944 S2) and it always returned about 10% less MPG in the winter than in the summer. The explanation is that colder air is denser and thus harder to push out of the way when moving down the road, so the engine has to work harder to maintain speed. A car will often be fractionally livelier in colder weather as well as the denser air allows more fuel to be burned in each combustion cycle, meaning potentially more power if you want to use it. (I also tracked the difference between Super Plus fuel and regular and discovered that Super Plus gave me about a 10% increase in fuel economy. Given that it costs about 5% more this made it a cheaper option, as well as needing to refuel less often.) If you are down 60miles on a tank at this time of year I'd be asking what else has changed in the car - the new tyre (singular? Surely you'd change them in pairs?) would be a good starting point. Check the pressure in it, and in the other tyres as well. Link to comment Share on other sites More sharing options...
zcacogp Posted February 26, 2020 Report Share Posted February 26, 2020 8 hours ago, DaveEFI said: I only ever fill up when near empty, and then brim it. And zero the MPG reader. Only been used around London in the winter, and get 15.7 mpg. 3.4S PDK. Whoosh - that's thirsty! 2.7 Gen1 Manual here and mine is currently showing 30.5mpg. And I live in London .... Link to comment Share on other sites More sharing options...
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