218i Fuel Trims & MPG
Discussion
Hi,
I posted yesterday about switching my 218i due to bad fuel economy and quite usefully it turned into a discussion about what could be causing it.
I have plugged my OBDII scanner in and let the engine warm up. The LTFT is showing +10 at idle and then when I revved it up the LTFT went down to just above 0.
I have booked it into the local indy specialist at a cost of £70 for a diagnosis - he says he has "special bmw diagnostic equipment" which will allow him to run tests. I mentioned the little test that I ran but he didn't seem to comment at all on it which is fine because I know he won't give free advice out.
The problem I have is bad mpg and nothing else. The onboard computer seems to overread by quite a bit which I'm not sure is of any relevance (?) unless there's a leak in the fuel tank or something? Either way, I go by how much it costs me each week and the truth is, I'm doing 40-60 miles a week and it's costing me around £15-£20 to fill up each week.
Obviously the indy wants to make money which is why he didn't comment on the trim values I told him about so can someone shed some light on this and whether what I've described might indicate an issue? Shall I just keep the appointment I made with the indy?
I posted yesterday about switching my 218i due to bad fuel economy and quite usefully it turned into a discussion about what could be causing it.
I have plugged my OBDII scanner in and let the engine warm up. The LTFT is showing +10 at idle and then when I revved it up the LTFT went down to just above 0.
I have booked it into the local indy specialist at a cost of £70 for a diagnosis - he says he has "special bmw diagnostic equipment" which will allow him to run tests. I mentioned the little test that I ran but he didn't seem to comment at all on it which is fine because I know he won't give free advice out.
The problem I have is bad mpg and nothing else. The onboard computer seems to overread by quite a bit which I'm not sure is of any relevance (?) unless there's a leak in the fuel tank or something? Either way, I go by how much it costs me each week and the truth is, I'm doing 40-60 miles a week and it's costing me around £15-£20 to fill up each week.
Obviously the indy wants to make money which is why he didn't comment on the trim values I told him about so can someone shed some light on this and whether what I've described might indicate an issue? Shall I just keep the appointment I made with the indy?
Quite a few variables there.
The 40 miles weeks…. That’s potentially a 3 mile journey (6 mile return), 7 days a week. What are your length of journeys ?
£15 per week… How much per litre are you paying ?
That could potentially be 20 mpg if you were paying a lot for fuel. Which for tiny journeys, where the engine doesn’t get luke warm, let alone hot, would seem alright to me.
The 40 miles weeks…. That’s potentially a 3 mile journey (6 mile return), 7 days a week. What are your length of journeys ?
£15 per week… How much per litre are you paying ?
That could potentially be 20 mpg if you were paying a lot for fuel. Which for tiny journeys, where the engine doesn’t get luke warm, let alone hot, would seem alright to me.
RUSSELLM said:
Quite a few variables there.
The 40 miles weeks…. That’s potentially a 3 mile journey (6 mile return), 7 days a week. What are your length of journeys ?
£15 per week… How much per litre are you paying ?
That could potentially be 20 mpg if you were paying a lot for fuel. Which for tiny journeys, where the engine doesn’t get luke warm, let alone hot, would seem alright to me.
I've done around 50 miles this week, all short journeys ie to the shops and back home, then to the gym etc. I dont commute anywhere as I'm a student. The 40 miles weeks…. That’s potentially a 3 mile journey (6 mile return), 7 days a week. What are your length of journeys ?
£15 per week… How much per litre are you paying ?
That could potentially be 20 mpg if you were paying a lot for fuel. Which for tiny journeys, where the engine doesn’t get luke warm, let alone hot, would seem alright to me.
Topped up earlier at 143p a litre, done the necessary calculations which gives 18mpg. Is it possible that this is due to the new rubbish E10 fuel? I usually go to Sainsbury's Petrol Station where its only E10. I know Tesco has E5 but its sold as premium fuel so I'm not sure whether it would be beneficial to buy E5 fuel.
I do around 6k miles a year which includes leisure trips to various places involving motorway driving where I usually get around 36-38 mpg on Eco mode driving at approximately 70mph.
scg1 said:
I've done around 50 miles this week, all short journeys ie to the shops and back home, then to the gym etc. I dont commute anywhere as I'm a student.
Topped up earlier at 143p a litre, done the necessary calculations which gives 18mpg. Is it possible that this is due to the new rubbish E10 fuel? I usually go to Sainsbury's Petrol Station where its only E10. I know Tesco has E5 but its sold as premium fuel so I'm not sure whether it would be beneficial to buy E5 fuel.
I do around 6k miles a year which includes leisure trips to various places involving motorway driving where I usually get around 36-38 mpg on Eco mode driving at approximately 70mph.
My wife has a 218i.Topped up earlier at 143p a litre, done the necessary calculations which gives 18mpg. Is it possible that this is due to the new rubbish E10 fuel? I usually go to Sainsbury's Petrol Station where its only E10. I know Tesco has E5 but its sold as premium fuel so I'm not sure whether it would be beneficial to buy E5 fuel.
I do around 6k miles a year which includes leisure trips to various places involving motorway driving where I usually get around 36-38 mpg on Eco mode driving at approximately 70mph.
She mostly does shortish journeys - 7 to 10 miles. with the odd 15 to 20 thrown in.
Her car, according to the OBC, has averaged 36mpg over 12K miles.
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