E36 318iS High Fuel Consumption ?
Discussion
1998 E36 318iS... I have consistently been averaging around 32-33mpg on mainly long 70 mile commutes, but lately the consumption has increased to about 22mpg (!).
This, combined with the fact that a work colleague who followed me in traffic remarked on the strong exhaust smell, has made me wonder about the cause.
Although this is not my main car ( I have a 2005 Alfa 156 JTDM 150 diesel for that ) I do use the BMW for commuting as well.
I was wondering if it could be the MAF ?
I have owned the car for 3 years and the mileage has increased from 92,000 to 122,000.
The car was not used at all for about 6 weeks, and I needed to charge the flat battery, but I have used it daily for this past week and was alarmed by the fuel usage !
Any ideas welcome !
Buy a cheap eml327 clone (or similar) OBD2 dongle, and matching app software: and read the codes.
It's now a very cheap way to actually find out, rather than guess.
[ETA: OBD2 is only available for >2001 cars, ok. I should have caught that. Sorry]
So what has changed: your use of the car? A few weeks non-use then short journeys only will make a huge difference to your mpg reported overall.
As will using it again for short journeys only in very cold weather.
How does it behave on longer journeys ...?
The classic cause of such things (low mpg even in cool weather) would be a failed thermostat, failing open - so that the engine runs too-cool, and never really gets out of warm-up cycle enrichment, burning excess fuel. this can be an easy and cheap fix...
It's now a very cheap way to actually find out, rather than guess.
[ETA: OBD2 is only available for >2001 cars, ok. I should have caught that. Sorry]
So what has changed: your use of the car? A few weeks non-use then short journeys only will make a huge difference to your mpg reported overall.
As will using it again for short journeys only in very cold weather.
How does it behave on longer journeys ...?
The classic cause of such things (low mpg even in cool weather) would be a failed thermostat, failing open - so that the engine runs too-cool, and never really gets out of warm-up cycle enrichment, burning excess fuel. this can be an easy and cheap fix...
Edited by Huff on Friday 30th December 03:53
Thanks for the reply.
You may have pointed to a possible cause; during this cold weather, the heater does not seem to be generating enough heat, which would suggest the thermostat.
I have a local Alfa specialist garage who have the diagnostic software, and they can always read any fault codes. As mine is a 1998 car, and I have an Apple computer, I may struggle to read them at home.
Anyway, thanks again for the advice, as always it is welcome !
All the best.
You may have pointed to a possible cause; during this cold weather, the heater does not seem to be generating enough heat, which would suggest the thermostat.
I have a local Alfa specialist garage who have the diagnostic software, and they can always read any fault codes. As mine is a 1998 car, and I have an Apple computer, I may struggle to read them at home.
Anyway, thanks again for the advice, as always it is welcome !
All the best.
"eml327 clone (or similar) OBD2 dongle" car too early for this so save your money.
Thermostat stuck open so engine not warming up fully could be the cause, you should see evidence of this in a low temp gauge reading. Cold start temp sensor (BMW part # 13621703993 DOUBLE TEMPERATURE SWITCH)
could be a possible cause also, really car needs plugging in to correct diag tool and codes read.
ETA:
Unplug your MAF, car will run on default setting, see if this makes any difference to mpg.
Thermostat stuck open so engine not warming up fully could be the cause, you should see evidence of this in a low temp gauge reading. Cold start temp sensor (BMW part # 13621703993 DOUBLE TEMPERATURE SWITCH)
could be a possible cause also, really car needs plugging in to correct diag tool and codes read.
ETA:
Unplug your MAF, car will run on default setting, see if this makes any difference to mpg.
Edited by E30M3SE on Saturday 31st December 10:32
I have the same car, albeit a '99 with 67k miles. For comparison, I get 35mpg+ on the motorway and 40+ on steady driving in the 50-60mph range. Did you put those wheels on or were they already on it? They're E46 wheels and larger than the standard ones for the E36 Sport model so the change in diameter could be having some kind of effect.
MitchT said:
........They're E46 wheels and larger than the standard ones for the E36 Sport model so the change in diameter could be having some kind of effect.....
They're "style 44" wheels that came in an 8x17 size and should be fitted with 225/45R17 tyres.That's a standard E36 & E46 size - so long as the correct size tyres are fitted there will be no change whatsoever in the diameter!
(E36 318iS' came as standard with a 7x16 wheel fitted with 225/50R16 tyres)
When I bought the car, it had a cat back MIltek stainless exhaust system already on, combined with an AMD remap for the exhaust.
I have kept full record of all the fuel consumption ( in a book with pen & paper !) over the 3 years I have had it.
It averages about 32 mpg, sometimes dropping to 28 if I drive it 'properly' (!) but it has never gone near 22mpg. This is mostly a range of decent A roads/ motorway on a commute. It even averaged 33 mpg to Monaco and back and that was at 'rapid progress' speeds...
The temperature gauge seems OK although it never has read over half way anyway...
I have ordered a thermostat ( Circoli I think) from Eurocarparts for a discounted £20 delivered ( including the housing) so I shall put that on anyway, and change the coolant obviously.
There are no engine lights on the dash, so presumably there would be no error codes if a diagnostic check was done ?
The wheels currently on it are the standard 16" ( those 17s in the photo are for track days only)
PS That spoiler has gone ....!
Presumably if I disconnect the MAF, the default settings would be the OEM factory ones ?
And would disconnecting the MAF harm the engine at all ?
Apologies for all these questions !
Happy New Year !
I have kept full record of all the fuel consumption ( in a book with pen & paper !) over the 3 years I have had it.
It averages about 32 mpg, sometimes dropping to 28 if I drive it 'properly' (!) but it has never gone near 22mpg. This is mostly a range of decent A roads/ motorway on a commute. It even averaged 33 mpg to Monaco and back and that was at 'rapid progress' speeds...
The temperature gauge seems OK although it never has read over half way anyway...
I have ordered a thermostat ( Circoli I think) from Eurocarparts for a discounted £20 delivered ( including the housing) so I shall put that on anyway, and change the coolant obviously.
There are no engine lights on the dash, so presumably there would be no error codes if a diagnostic check was done ?
The wheels currently on it are the standard 16" ( those 17s in the photo are for track days only)
PS That spoiler has gone ....!
Presumably if I disconnect the MAF, the default settings would be the OEM factory ones ?
And would disconnecting the MAF harm the engine at all ?
Apologies for all these questions !
Happy New Year !
No engine lights does not mean no error codes unfortunately/fortunately, depending on how you look at it.
Disconnecting the MAF will not adversely affect the engine, it just means the the fie tuning of the fuel/air mixture does not occur & if the mileage/gallon goes back up, could highlight the fault.
Personally, I doubt it is the MAF. The only MAF failure I have witnessed gave quite severe changes in engine power causing EXTREME jerkiness to the power delivery.
Disconnecting the MAF will not adversely affect the engine, it just means the the fie tuning of the fuel/air mixture does not occur & if the mileage/gallon goes back up, could highlight the fault.
Personally, I doubt it is the MAF. The only MAF failure I have witnessed gave quite severe changes in engine power causing EXTREME jerkiness to the power delivery.
Thanks for all the advice. Will disconnect the MAF this coming week and see if that has any effect.
PS Has anyone got a spare passenger side foglamp mounting...I attempted to change the bulb in the very cold weather we have had in Co Durham recently, and the brittle plastic tab which releases the unit snapped (!). I may even get some plastic blanks if they fit easily...!
Paul
PS Has anyone got a spare passenger side foglamp mounting...I attempted to change the bulb in the very cold weather we have had in Co Durham recently, and the brittle plastic tab which releases the unit snapped (!). I may even get some plastic blanks if they fit easily...!
Paul
with the MAF disconnected the cars ECU will switch to a default factory setting that will cause it to run rich constantly regardless of engine temperature, so you might not notice any real change in fuel usage.
It wont hurt the engine running it with the MAF disconnected for a short time, but it could start causing issues if you do it over a long period of time.
The first thing I would do is get the codes read before you start guessing at what could be happening - The car could be telling you what's wrong already.
If the thermostat goes faulty, then you'll usually notice that the temp needle struggles to get up to the midway point on the gauge, and as soon as you get any speed up, the needle drops back to the blue sector straight away. Added to that, you'll be lucky to get luke-warm air coming out of the heater vents, even when it's set to it's highest temperature.
As I say though, get the codes read first!
It wont hurt the engine running it with the MAF disconnected for a short time, but it could start causing issues if you do it over a long period of time.
The first thing I would do is get the codes read before you start guessing at what could be happening - The car could be telling you what's wrong already.
If the thermostat goes faulty, then you'll usually notice that the temp needle struggles to get up to the midway point on the gauge, and as soon as you get any speed up, the needle drops back to the blue sector straight away. Added to that, you'll be lucky to get luke-warm air coming out of the heater vents, even when it's set to it's highest temperature.
As I say though, get the codes read first!
Did you get to the bottom of this and was your gauge wandering? If not I doubt the thermostat was too much at fault. Mine was all over the shop before the 'stat replacement.
http://www.pistonheads.com/gassing/topic.asp?t=148...
For the record my E36 323i on a genuine BMW thermostat used to get the following:
29MPG around town
33-35MPG on a run.
E46 M3:
18-22MPG around town depending on my foot
30-33MPG on a run below 80ish.
If you have a BMW connector to OBD conversion and are near Warwick I am happy to read the codes for you ; I have INPA which has been very handy on my car.
The M3 had a wondering gauge but I do not know whether the thermostat is at fault. The stock thermostat opens alot earlier than other modern thermostats, 80 degrees to be exact compared to the E36's 92 degree item or that was what the replacement opened at.
http://www.pistonheads.com/gassing/topic.asp?t=148...
For the record my E36 323i on a genuine BMW thermostat used to get the following:
29MPG around town
33-35MPG on a run.
E46 M3:
18-22MPG around town depending on my foot
30-33MPG on a run below 80ish.
If you have a BMW connector to OBD conversion and are near Warwick I am happy to read the codes for you ; I have INPA which has been very handy on my car.
The M3 had a wondering gauge but I do not know whether the thermostat is at fault. The stock thermostat opens alot earlier than other modern thermostats, 80 degrees to be exact compared to the E36's 92 degree item or that was what the replacement opened at.
Edited by SebringMan on Tuesday 3rd January 11:02
Thanks for all the input.
I drove the car yesterday with the MAF disconnected...it drove 'better' in that it seemed to have more power ( but then again it should do I suppose ) The throttle response was smoother for the first inch or so of the pedal...not sure if that is related or not. It has always seemed a bit 'sticky' for the first 1/2 inch of travel....(I suspect that the throttle body aperture may need a clean where the butterfly closes ?)
The temperature gauge reads about 1/3 of the way across, and is steady, so as you say probably points to the thermostat being OK.
I shall book it in with my local Alfa/BMW indy ( I live in Co Durham ) to get the codes read.
Its a bit too cold up here to be under the bonnet in the wilds of Co Durham !!
Croft Circuit a couple of years ago in much warmer weather !!
I drove the car yesterday with the MAF disconnected...it drove 'better' in that it seemed to have more power ( but then again it should do I suppose ) The throttle response was smoother for the first inch or so of the pedal...not sure if that is related or not. It has always seemed a bit 'sticky' for the first 1/2 inch of travel....(I suspect that the throttle body aperture may need a clean where the butterfly closes ?)
The temperature gauge reads about 1/3 of the way across, and is steady, so as you say probably points to the thermostat being OK.
I shall book it in with my local Alfa/BMW indy ( I live in Co Durham ) to get the codes read.
Its a bit too cold up here to be under the bonnet in the wilds of Co Durham !!
Croft Circuit a couple of years ago in much warmer weather !!
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