#1: Very poor MPG Author: Austin, Location: TelfordPosted: Thu Jan 24, 2013 11:30 am ---- Hi guys,
Had my 206 1.4 8v for a week now, put £25 in the tank from empty and have only managed to get 88 mile! Quick calculation and that's about 21mpg!... When car was in garage last week they put scanner on it and said there was a lambda sensor fault but they cleared it, haven't had the engine management light come on since. Would this faulty sensor possibly affect the fuel consumption so bad to get 21mpg?!
Thanks
Austin
#2: Re: Very poor MPG Author: 00budham00, Location: IpsPosted: Thu Jan 24, 2013 11:32 am ---- 1.4 has injectors?
#3: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Thu Jan 24, 2013 11:39 am ---- Not sure, I think it's due a service tbh. Planning on doing that tomorrow but surely this won't make a huge difference?
#4: Re: Very poor MPG Author: 14hdi, Posted: Thu Jan 24, 2013 4:15 pm ---- Wont make that kind of difference but you'll be surprised what it will do, make sure you change the fuel filter to as no one ever does these.
#5: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Thu Jan 24, 2013 4:23 pm ---- Apparently the fuel filter is self cleaning on the 1.4 8v :S
#6: Re: Very poor MPG Author: Steve206, Location: UKPosted: Thu Jan 24, 2013 4:32 pm ----
00budham00 wrote:
1.4 has injectors?
Random comment, unless im missing something?
Yes, a lambda fault may cause excessive fuel problems. It is one of the ways the ECU controls fuelling from the emissions Could also be MAP sensor related, but if you've got a lambda fault, its the starting point. Give the car a good service, and see how it improves.
#7: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Thu Jan 24, 2013 5:25 pm ----
Steve206 wrote:
00budham00 wrote:
1.4 has injectors?
Random comment, unless im missing something?
Yes, a lambda fault may cause excessive fuel problems. It is one of the ways the ECU controls fuelling from the emissions Could also be MAP sensor related, but if you've got a lambda fault, its the starting point. Give the car a good service, and see how it improves.
Thanks, going to give it a good service this weekend and check the simply things first. Also would it be an idea to disconnect battery and reset ecu? as the faulty sensor could have stored incorrect data, so thinking by resetting it and let the car idle for 5-10 mins the data will change and then fuel correctly.
Correct me if that is a load of b******s! Lol
Austin
#8: Re: Very poor MPG Author: Steve206, Location: UKPosted: Thu Jan 24, 2013 6:45 pm ---- No that's correct, when a fault has been cleared, its a good idea to let the ecu relearn the sensor readings. Boot down safely, and restart. What year is your car?
#9: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Fri Jan 25, 2013 1:26 am ---- Ok will give this a try after work. It's 2004 '04 plate mate.
#10: Re: Very poor MPG Author: Icetto, Location: Cape TownPosted: Fri Jan 25, 2013 1:28 am ---- Check out the lambda sensor. It may have become packed up and therefore not working properly and causing over-fueling
#11: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Fri Jan 25, 2013 1:55 am ----
Icetto wrote:
Check out the lambda sensor. It may have become packed up and therefore not working properly and causing over-fueling
How is best to check this? will i need to get it plugged in to diagnostics?
Like i say i haven't got EML anymore after the fault was cleared.
#12: Re: Very poor MPG Author: Icetto, Location: Cape TownPosted: Fri Jan 25, 2013 2:42 am ----
Austin wrote:
Icetto wrote:
Check out the lambda sensor. It may have become packed up and therefore not working properly and causing over-fueling
How is best to check this? will i need to get it plugged in to diagnostics?
Like i say i haven't got EML anymore after the fault was cleared.
Nope. Someone has to literally check the sensor (yourself or mechanic if you are not good with it).
#13: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Fri Jan 25, 2013 3:30 am ---- Thanks mate, it makes perfect sense now! I'm taking it to my local garage tonight, they are going to run diagnostics and monitor the lambda readings. I am an electrician by trade but car electrics baffle me! lol
#14: Re: Very poor MPG Author: Steve206, Location: UKPosted: Fri Jan 25, 2013 4:51 am ---- Just keep in mind though, if you have a leak in the system, or the map sensor, or coolant sensor is giving incorrect readings, these all have a knock on effect on the lambda sensor. A lambda sensor just checks the emissions and tells the ecu. If another part has failed before the lambda, that will be the cause of the problem.
In my experience my lambda sensor had just died, but I did check out my map sensor, just to rule it out. Also, after clearing the fault, mine came back on within 10 miles of driving.
When a sensor relating to fuelling fails, the car will run on pre set figures, so I don't know if it would necessarily give you such a poor MPG.
#15: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Fri Jan 25, 2013 5:59 am ---- Thanks Steve... I think the coolant/thermostat is ok, running temperature seems ok and when car is first started it high revs then idle lowers once temp is up. Anyway of checking the MAP sensor? if this is faulty it should show up on the diagnositcs?
I don't think the lambda has failed completely because the EML has cleared now, but possibly it is on its way out and telling the ECU it is running lean so chucking more fuel in.
#16: Re: Very poor MPG Author: MrBSI, Location: What's it to you? ? ?Posted: Fri Jan 25, 2013 10:26 am ---- Its multiplexed, fill the tank to the brim to reset the fuel gauge correctly & then work out the mpg.
OR
Fit the 3 line MFD & the trip computer button & let the BSI unit work it out for you
TU3 average mpg, mine does between 32 / 33 mpg average around town on the trip computer.
#17: Re: Very poor MPG Author: Edward, Location: In the garagePosted: Fri Jan 25, 2013 10:38 am ---- Biggest impact on MPG is how the car is used, short runs or lots of sitting in traffic jams isn't going to help.
#18: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Fri Jan 25, 2013 11:14 am ---- Ok guys... It's been to the garage this afternoon, plugged in diagnostics tester and there isn't any faults on the car since the lambda fault was reset last week :S
Have given the car a service aswell, filter and plugs all looked ok. Have disconnected the battery (safely) to Reset ecu, just going to monitor it over next few days. If it's still bad then where do I look next?
I have been doing 6 mile journey to work on a fuel carriageway and also around town, but I have been driving like a granny all week :S
#19: Re: Very poor MPG Author: scottiedickins, Posted: Sun Jan 27, 2013 2:20 pm ---- hey mate dont know if this has been solved but this info might be of help
i had an audi a4 1.8 petrol the fuel was getting raped on that like to the point i was getting 13mpg took it in for its mot and it failed on emissions after a lot of money spent trying to find were the problem was it turned out to be a faulty maf sensor when i asked the garage why this didnt show up and fault codes he told me that as long as there is not a break in the line it wont show up as being a fault but what had happend is the maf sensor was telling the car that it was sucking in barleyany air the lamba was then telling the ecu that it wasnt the right mix so the ecu then pushed through more fuel to compansate so although i had a fault for the lamba it turned out to be somthing completly different might be worth looking into might save you a few quid hope it helps
#20: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Sun Jan 27, 2013 3:05 pm ---- Thanks for that mate. It does seem to be running better after a good service. Also have cleaned MAP sensor and throttle bodie today, had alot of carbon build up. Gona see how it goes over the next week or so, if still a problem then gona try new MAP and bank 1 lamba sensors.
#21: Re: Very poor MPG Author: Steve206, Location: UKPosted: Mon Jan 28, 2013 2:49 am ---- There both expensive to replace, so unless there showing a fault, I'd see how it goes.
#22: Re: Very poor MPG Author: devotedsniper, Location: Tamworth, StaffordshirePosted: Mon Jan 28, 2013 7:30 am ---- Check your exhaust ain't leaking, whenever I've had a leak it's wreaked havoc on my mpg (my old 1.4 did 10 miles less to the gallon, my 307 2L HDi lost 160 miles from a tank).
#23: Re: Very poor MPG Author: Austin, Location: TelfordPosted: Tue Feb 12, 2013 5:28 pm ---- Well guys... as you can see from my signature the MPG has dramatically improved so far. Brimmed the tank and got 340 miles which comes out at 36.4mpg which i am alot happier with. I think a good service and clean of the MAP/Throttle Body did the trick thanks for all the info and help!
#24: Re: Very poor MPG Author: Deano, Posted: Wed Feb 13, 2013 2:37 am ---- Hi I have bad mpg on live data I get fuel system ol fault which I belive is open loop fault anyone got any ideas on what this could mean ?
#25: Re: Very poor MPG Author: AX-Rated, Location: Swansea, WalesPosted: Wed Feb 13, 2013 2:04 pm ---- Open loop means that the lambda sensor isn't reporting its oxygen levels back to the ECU hence a open loop.
Look on your live data for the lambda readings and if theyre not there or wildly out then its either a heater fault on the lambda sensor or the lambda sensor has failed.
Unless someone else thinks otherwise.
#26: Re: Very poor MPG Author: Rob2859, Location: HalifaxPosted: Wed Feb 13, 2013 2:46 pm ---- If it makes you feel better I can only dream of such economy in my Hilux
#27: Re: Very poor MPG Author: Barking, Location: sarcasm-in-shedloadsPosted: Wed Feb 13, 2013 3:12 pm ---- Defrosting the car and then a 250 metre trip in mine = 6.8 mpg (according to the onboard computer)
Life's never boring in a 1.4 TSI™
#28: Re: Very poor MPG Author: daykes1, Location: Ledbury, HerefordshirePosted: Fri Mar 29, 2013 3:47 pm ---- had all the same issues & it turned out to be the coolant sensor - the green one
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