My M30 uses 20.5L/100km (11.5 miles a gallon)

[F4Phantom]

Is this normal. I think it may be a bit thristy. If it turns out thirsty what are the basics to check. Eg, injectors, air filter, fuel filter?? In my diesel 4x4 the air filter has massive impact on economy so I checked mine and it's good. The engine has done 270,000km/ around 170,000 miles so it aint new any more. I suspect a high km engine just tends to use a bit more. Thanks.

[ericcamaro]

thats excessive, Start with air filter, then fuel filter, then do your Oxygen sensor, then check the ignition system (cap, rotor, plugs, wires..etc). if none of that pans out check out your injectors make sure you dont have one stuck open, but it should be apparent when you pull the plugs if a cylinder is running rich. If an injector is stuck open the spark plug usually looks really clean, as if it was sprayed with a solution over and over to flush out all the carbon. let us know what it turns out to be, i got my money on the o2 sensor.

[Gayle]

I want to hear the answers to this because I consider my gas mileage pathetic--18mpg with majority highway miles but I am a spirited driver.

(Lately I have really been enjoying leaving tail gating trucks in the dust on freeway exchanges where my car really holds the road on the curve and they don't. Then polish it off with a pedel to the metal monent when I hit the new freeway.)

Mine has under 100k miles and is a chipped 535. Those premium gas prices are painful. Have been thinking it is time to pull out the prior owners maintence records and see if the oxygen sensor has been changed.

[angrypancake]

18 pathetic? i'm lucky to get 14....

[Gayle]

18 pathetic? i'm lucky to get 14....

on the razor scooter???

[F4Phantom]

thats excessive, Start with air filter, then fuel filter, then do your Oxygen sensor, then check the ignition system (cap, rotor, plugs, wires..etc). if none of that pans out check out your injectors make sure you dont have one stuck open, but it should be apparent when you pull the plugs if a cylinder is running rich. If an injector is stuck open the spark plug usually looks really clean, as if it was sprayed with a solution over and over to flush out all the carbon. let us know what it turns out to be, i got my money on the o2 sensor.


I think I will check my O2 sensor - thats the thing plugged into the exhaust right? I will also change my fuel filter and see where that leads me. One potential problem is that these figures are off the OBC. Could this be wrong? I have done some mental arithmetic and it does not seem to be out by much but I do remember a post where someone was talking about changing a figure used by the OBC to run in it's calculations.

[Alexlind123]

The OBC shouldnt be off by more than a few percent...

[BillionPa]

any of you single fuel filter people thought about modding to a dual parallel filter system like the V8s use?

oh and yeah, i'd check the O2 sensors, because it wouldnt be the air filter, but it could be the air sensor giving a faulty base reading, and the O2 sensor too messed up to compensate.

after you replace the O2 sensor(s), do an ecu reset.

and if you want to experiment, adding 3oz of acetone per 10 gallons of gas changes the surface tension of the gas without altering the octane rating, allowing the gas to vaporize better, and therefore less of it needed to produce the same amount of power.

and yes i have actually tested it myself, my gas mileage went up 16%

[Paul in NZ]

i am averaging about 20 mpg but that to an imperial gallon,most of it petty easy driving too,not much stop start

[pundit]

My 535i auto gets around 14.5litres/100km (about 20 mpg) driving between Emerald in the Dandenongs and Burwood commuting to work in 50/50 semi cruise/peak hour traffic.
I can get bewteen 9.5 and 10.5 litres (30-27mpg) at 100kmh and 115kmh respectivley when highway cruising.

[bill g]

I know this is basic but make sure you are not driving around with handbrake partly on or brakes binding, or with big load on board eg. several bags of cement in boot, mother-in-law (sorry, old gag).
Also that fuel consumption would not be bad if all your driving is in ridiculously busy stop start traffic where you spend a lot of time idling.

Bill G Melbourne Aus

[F4Phantom]

Just did a crash course in O2 lamda sensors and I had no idea of the large range of effects it has on the car. I kind of thought it was a bit like early carbon emissions canisters - dont do much, but was a good idea at the time. I will call BMW monday to ask about prices and compare with the online bmw place.

[F4Phantom]

I know this is basic but make sure you are not driving around with handbrake partly on or brakes binding, or with big load on board eg. several bags of cement in boot, mother-in-law (sorry, old gag).
Also that fuel consumption would not be bad if all your driving is in ridiculously busy stop start traffic where you spend a lot of time idling.

Bill G Melbourne Aus

Nah I am really careful with the basics like that. The car gets driven very easy and although does have a couple of kids in the back I am not sure this would account for nearly half the economy of others here.

BTW does this engine had 2x sensors, one before the C-Converter and one after? or is it just the simple procedure of replacing this

Oxygen Sensor
C5010-33552
In Stock Bosch (OEM) $189.00 $113.13

Thanks again.

[sKilled]

I am also a bit of a technical noob, but would cleaning the MAF help? Also, the lambda sensor would cause major havoc as I have heard this on many occasions in regards to other vehicles. Another consideration would be to check the octane rating of your fuel - use 95 or greater, 98 being optimal as any less would greatly increase you consumption. Do you tank an ethanol mix? They are also not as efficient apparently. Also worth considering/investigating.

[BigKriss]

I regulary get 17+ litres per 100kms for city driving. Its not that bad. Maybe consider a wideband 02 sensor.

[Dave M]

and if you want to experiment, adding 3oz of acetone per 10 gallons of gas changes the surface tension of the gas without altering the octane rating, allowing the gas to vaporize better, and therefore less of it needed to produce the same amount of power.

and yes i have actually tested it myself, my gas mileage went up 16%

Could you please enlighten us further on the hows and whats. Potential drawbacks?

Dave M

[Dave M]

OK, found some info on acetone (http://www.pureenergysystems.com/news/2005/03/17/6900069_Acetone/). Mythbusters?

An excerpt for Winfred if he's considering it for the Dodge.

A tiny bit of acetone in diesel fuel can stop the black smoke when the rack is all the way at full throttle. You will notice that the exhaust soot will be greatly reduced and your truck or car runs smoother.

Guess you can't have your cake and eat it too ;)

Dave M

[Bellicose Right Winger]

Mine was off by 8%. I use a 920 correction factor in the OBC.

Paul Shovestul



The OBC shouldnt be off by more than a few percent...

[Derek A.]

I get 17 city 21 highway ( 80+mph). Gotta remember these is an older engine design. Its like a tractor engine with fuel injection !

[Gayle]

I regulary get 17+ litres per 100kms for city driving. Its not that bad. Maybe consider a wideband 02 sensor.



What is a wideband 02 sensor?

And what are you doing posting during your meet? You are supposed to be buzy drinking beer, eating barbeque, and swapping stories.

[joshua43214]

Check in the following order for poor fuel economy,

Air filter
Ignition parts
O2 sensor
AFM

The fuel filter should never cause high fuel consumption, since it will lower fuel delivery when it clogs up.

Make sure you have no vacuum leaks.

The O2 sensor is a very common cause of excessive fuel usage.

[BigKriss]

What is a wideband 02 sensor? And what are you doing posting during your meet? You are supposed to be buzy drinking beer, eating barbeque, and swapping stories.I'll reply about the wbo2 when I can speak one with one word tied behind my foot in front of my mouth... but atm we've drunk a shitload o beer and chewed down a truckload of kangaroo steaks... the possums came and took away the rest and the bush turkeys are roosting in the trees now trying to **** on our cars... and there are 4 computers in the house but we're hardly in a fit state to use them... plus this fukem5 guy is pissin us off real bad... Kristian :)

[Traian]

This thread is making me feel better about my consumption hehe. According to the OBC I get 14.0 L/100k which is like over 50/50 hwy/city; according to my own measurements it´s probably a little less, maybe 13.8 or so overall. I thought that was pretty bad, because BMW lists the new E60 550i´s consumption around 13.0 or so and it´s got another 800cc. And on top of that I tend to drive pretty relaxed most of the time.

Did you check fuel lines? Maybe you have a leak. That might explain why the car runs good otherwise.

[fukem5]

Check in the following order for poor fuel economy,

Air filter
Ignition parts
O2 sensor
AFM

The fuel filter should never cause high fuel consumption, since it will lower fuel delivery when it clogs up.

Make sure you have no vacuum leaks.

The O2 sensor is a very common cause of excessive fuel usage.One thing about this forum in particular, u really mustn't listen to too many of the contributirs, the first thing to check is the valves cos they let the fuel mixture into the cylinders & on an M30 they are too damn big: Jezt change em out for small ones next time u chg your plugs, but I tell u what I'll raise the matter w my cousins at BMW shortly and ask them to help.

In the meanwhile I've heard you can run freon in the EFI (works in a BMW like Nitrous works in a Rotary) and even remove the AC like Jon K, but he is not as smart as he thinks he is... He and Regal632's Tin soldiers will probably tell you this will fix everything but I doubt it, which is why I'll talk to my cousins ok bro? NO worries bro, its kool too I'll accept payment when u save ur hard earned petrol money from pimpin' drugs and ****...

[mattyb]

mate your full of it. you wouldnt know a slimy maggot from a local person in your village. I doubt u have ever seen a car let alone driven one. shut the fk up if dont have a clue what ur talkin about!!!!

[fukem5]

mate your full of it. you wouldnt know a slimy maggot from a local person in your village. I doubt u have ever seen a car let alone driven one. shut the fk up if dont have a clue what ur talkin about!!!!I don't see anyone rollig out a red carpet into Bavaria for you ratty****; it takes a lot of service station experince (ie more than pumping gas) to be acknowledged by a major manufacturer as having inoovation skills that would be helpful in developing the next 1200rwhp quad turbo, 3-cylinder hybrid M5.

My cousins are laughing at your best efforts w ur 540 bro, maybe u should resign from the board in shame now rather than abuse fully verified by paypal Prima Donas like me that have spent so long contributing to the Bimmer community.

[mattyb]

i dont care what u think. just wait till jeff gets to stick it up u!!!

[Dave M]

I don't see anyone rollig out a red carpet into Bavaria for you ratty****; it takes a lot of service station experince (ie more than pumping gas) to be acknowledged by a major manufacturer as having inoovation skills that would be helpful in developing the next 1200rwhp quad turbo, 3-cylinder hybrid M5.

My cousins are laughing at your best efforts w ur 540 bro, maybe u should resign from the board in shame now rather than abuse fully verified by paypal Prima Donas like me that have spent so long contributing to the Bimmer community.


Finally, someone who knows what there talkin abouts.

My cousins are always laughing and $hit at stupid people and I like to do it too cuz it makes me feel reaalyy good inside. Thats funny, we have so much in common.

You're right about Jeff and Regal, they couldn't design a good turbo hybrid like guys like us. Mostly, they just blow hot air (light jons silly little contraptions). Geez, I hope they don't read this.

Keepin it real,

Dave M

[Gayle]

Finally, someone who knows what there talkin abouts.

My cousins are always laughing and $hit at stupid people and I like to do it too cuz it makes me feel reaalyy good inside. Thats funny, we have so much in common.

You're right about Jeff and Regal, they couldn't design a good turbo hybrid like guys like us. Mostly, they just blow hot air (light jons silly little contraptions). Geez, I hope they don't read this.

Keepin it real,

Dave M

Dave

This post doesn't sound like you. Is it tongue and cheek? Or leave your computer unguarded and is someone else posting under your name?

[Adnan]

BTW does this engine had 2x sensors, one before the C-Converter and one after? or is it just the simple procedure of replacing this

Oxygen Sensor
C5010-33552
In Stock Bosch (OEM) $189.00 $113.13

Thanks again.

The M30 has just one O2 sensor. It can be a bear to remove, however.

My '91 M30 gives me 20 mpg with a 50/50 mix of highway and city. Have you considered that you may be driving the ol' E34 as fast as an F4 ;) ? On mine, the fuel consumption goes up significantly at 70 MPH versus 50 MPH.

Regards,
Adnan

[F4Phantom]

The M30 has just one O2 sensor. It can be a bear to remove, however.

My '91 M30 gives me 20 mpg with a 50/50 mix of highway and city. Have you considered that you may be driving the ol' E34 as fast as an F4 ;) ? On mine, the fuel consumption goes up significantly at 50 MPH versus 70 MPH.

Regards,
Adnan

Yeah I dont think so, I like to give it a good rpm range occasionally but it is mostly my wife driving local trips. She drives very easy. Also the previous owner kept huge logs and always averaged 12.5L. The only main change I have made is a new tranny but I cant imagine a new/rebuilt tranny could add fuel like this - or perhaps the new tranny needs to be worn in? and loosen up a bit, cause if it does then the 'driving with handbrake' idea could be actually happening through the tranny. Either way my 02 sensor (lamda) is getting replaced.

Some of these replys I am having a very hard time understanding, and its even harder to just accept them as jokes because they are not funny. I recon if your trying to be funny, because there are no facial expressions to detect you need to be extra funny or poeple like me become confused on so many levels!

[Qube]

That's absolutely horrid. With A/C on I get at worst 16L/100KM

[califblue]

The Big 6 as the M30 is so aptly called likes to Drink Petroleum products...16-18 MPH here with city/fwy driving and best is 23.8 MPG@ 80mph w/ cruse control

I always drive with A/C on:D

And compared to my Hot Rodded 1835cc VW THING w/ dual 44 Webbers this is an Ecno Box!:p

[mamilapon]

I think I will check my O2 sensor - thats the thing plugged into the exhaust right? I will also change my fuel filter and see where that leads me. One potential problem is that these figures are off the OBC. Could this be wrong? I have done some mental arithmetic and it does not seem to be out by much but I do remember a post where someone was talking about changing a figure used by the OBC to run in it's calculations.
I would't trust my OBC, each time I press consump, I crap my pants!!

[McWatters]

If anyone watches Myth busters you will know that infact, using ur AC and driving uses less gas then driving with ur windows down..

cheers

J.McWatters

[BillionPa]

but is that true on an E34 with a very efficient aerodynamic profile?

[ILoveMPower]

My average is 19.1mpg, with basically like ALL spirited highway miles :)


If anyone watches Myth busters you will know that infact, using ur AC and driving uses less gas then driving with ur windows down..

cheers

J.McWatters

I didn't know that, but I definitely prefer windows down over A/C.

[Nick.Hay]

Mine is quite high too...

about 19L/100km

[Ausmpower]

No one has mentioned the temp sensor used for the DME, if it's faulty you'll constantly run rich (DME thinks the engine is cold and runs open loop).

I'd try O2 first then temp sensor-try one from a wrecker.

I get 13.6 L/100km to work and back stop-start no freeway and 9.8 l/100 constant 110kph highway (M30 535 manual).

[genphreak]

No one has mentioned the temp sensor used for the DME, if it's faulty you'll constantly run rich (DME thinks the engine is cold and runs open loop).

I'd try O2 first then temp sensor-try one from a wrecker.

I get 13.6 L/100km to work and back stop-start no freeway and 9.8 l/100 constant 110kph highway (M30 535 manual).Yes, the book for an M30 auto e34 is like 16.9L/100km on the city cycle and 10.5L/100km at 120km highway cycle. Getting better is a matter of careful driving. My M30 used 20mpg before I changed the rotor cap and plugged the hole in the booster non-return valve (changed it actually but the 2mm hole only needed plugging). Maybe there was a leak in the intake too. Who knows. But I agree with what Joshua has said on this.

The biggest problem with factory M30 consumption is the city cycle. Big valved engine- great when you open her up but idling around she'll always use more than a vanos engine with smarter electronics like knock-sensing ECU and WBO2 sensors as Kristian said.

Good luck F4, let us know how you go w the O2 sensor. :) Nick

[Ausmpower]

Hey Nick how are ya??

Just went and double checked cons2 on my obc 13.9 l/100km, I reset it 2 weeks ago so it's been chugging away. Mines a manual though and I certainly don't baby it!
My last top up was 35 litres 258 km ago that works out to 13.57 L/100.

Vacuum leaks after the afm will make it run lean if severe enough, not rich.

A sticking AFM will make you rich though.

my money is on the O2 probe or airfilter.

[genphreak]

Hey Nick how are ya??

Just went and double checked cons2 on my obc 13.9 l/100km, I reset it 2 weeks ago so it's been chugging away. Mines a manual though and I certainly don't baby it!
My last top up was 35 litres 258 km ago that works out to 13.57 L/100.

Vacuum leaks after the afm will make it run lean if severe enough, not rich.

A sticking AFM will make you rich though.

my money is on the O2 probe or airfilter. Hey dude! The manual is more frugal than the auto by .5L or so.

If F4s car is running lean it would be using more fuel too. The ECU will be trying weird things all the time, power would be reduced so his foot would be down more.

However as these cars are geared long they use a lot more fuel off the mark, in favour of less (and a nicer feel) at 'Bahnspeed. Given we have 110kmh speed limits I always wanted to get a shallower diff ratio for mine. It would help economy enormously, and give me better off the mark pickup, not that many beat me from the lights at present.

A mad postie tried to kill me last night, he was pulling 90kph in a 60 zone, weaving traffic wildly- in the rain! Was driving in an empty diesel 3T transit van unladen, I reckon he damn near collided twice best I could see aheadwhen it happened. I was going cool, but took himj at every light not even thinking about it. Caught up to him here and there cos he couldn't beat the lights for some time. He was very slow off the mark so he was behind me even tho I wasn't racing at all in the really bad conditions. But his van ironed out hard- I was wondering where he was when all of a sudden some dingbat in an e46 decided to stop in the middle of the road. I swapped lanes but had to step on it as he'd hyperspaced up behind me. A little way after that he slung it sideways through 3 lanes of traffic doing 70kph juz cos he wanted to pass some tool dawdling in the right lane. All the dumb beaurocrats buy automatics, so that van would be hard on the gas too.. I wonder how much extra diesel he used doing all his bravado.

Probably a whole lot less than our M30s- not fair... :) Nick

[Gene in NC]

F4Phantom, did I miss what the plugs tell you about operating: rich, lean, clean running. Has it become unfashionable to read the plugs? Pull the plugs and compare them to a plug condition chart. Are you running the BMW recommended plugs?

These comments are not really directed at you but all the posters on this thread. Don't see much reference to plug reading. Those who have not lived with two stroke off road motorcycles for enduros and motorcross, or drag racing, etc. etc. may need to start from square one on plug reading but the rewards are worth the effort.

[genphreak]

F4Phantom, did I miss what the plugs tell you about operating: rich, lean, clean running. Has it become unfashionable to read the plugs? Pull the plugs and compare them to a plug condition chart. Are you running the BMW recommended plugs?

These comments are not really directed at you but all the posters on this thread. Don't see much reference to plug reading. Those who have not lived with two stroke off road motorcycles for enduros and motorcross, or drag racing, etc. etc. may need to start from square one on plug reading but the rewards are worth the effort.Yes that's a very good point :),we have gone past the first check. I expect also that with Motronic it can run easily lean out in traffic, go rich under power or at different temperatures or so on, so reading the plugs might not be as perfect a test as it should be... and vaccum leaks, etc. are damn common. Probably the other bases need to be checked too but this is a very good point Gene!

[genphreak]

Yes, the book for an M30 auto e34 is like 16.9L/100km on the city cycle and 10.5L/100km at 120km highway cycle. Getting better is a matter of careful driving. My M30 used 20mpg before I changed the rotor cap and plugged the hole in the booster non-return valve (changed it actually but the 2mm hole only needed plugging). Maybe there was a leak in the intake too. Who knows. But I agree with what Joshua has said on this.

The biggest problem with factory M30 consumption is the city cycle. Big valved engine- great when you open her up but idling around she'll always use more than a vanos engine with smarter electronics like knock-sensing ECU and WBO2 sensors as Kristian said.

Good luck F4, let us know how you go w the O2 sensor. :) NickHere's a pic of the non-return valve (elbow) for F4Phantom.
Rubber bung is almost visible inside the bend of the elbow.
:) Cheers Cary!
http://members.roadfly.org/Maclover94/Dirtym302.JPG
It's right there, just under the throttle and Cruise control cables. :) Nick

[Nick.Hay]

NEW HIGHS!!

Mine now uses 23L/100km!! Probably doesn't help that I continue to drive it on 5 cylinders :(

Other car will be fixed soon, then the 535i can go in the shed, and begin to be rejuvenated!!