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z4 35i fuel consumption

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
HillWalker
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z4 35i fuel consumption

Post by HillWalker » Fri Jan 12, 2018 11:05 pm

In my younger days it was known as having a decoke, a couple of hours whip the head off clean it up put it back together job done, if we wanted to get really racy we'd take it for a Crypton tune up then you were really flying, the good old days, and petrol 5 Bob a gallon. :wink:

flybobbie
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z4 35i fuel consumption

Post by flybobbie » Fri Jan 12, 2018 11:39 pm

I had carbon build on a aero engine.
The valve got jammed open, struck by piston, punctured the piston and very rough engine. Put the plane down in a field.
Very exciting for me and my trial flight passengers.

Busterboo
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z4 35i fuel consumption

Post by Busterboo » Sat Jan 13, 2018 2:56 am

sachak wrote: Thu Jan 11, 2018 11:12 amSo the car is at the carbon doctor ... they are also going to run a bunch of diagnosis on the car and see if they can pick anything else up that might relate to the high fuel consumption ...
What did they say?
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sachak
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z4 35i fuel consumption

Post by sachak » Sat Jan 13, 2018 8:46 am

Busterboo wrote: Sat Jan 13, 2018 2:56 am
sachak wrote: Thu Jan 11, 2018 11:12 amSo the car is at the carbon doctor ... they are also going to run a bunch of diagnosis on the car and see if they can pick anything else up that might relate to the high fuel consumption ...
What did they say?
We ran diagnostics and nothing came up :( we ran real time logs while taking the car for a drive and couldn't pick anything up either.
However I do keep getting the error:

2CB8 - DME: Oxygen sensor after catalytic converter: Signal fixed at Rich.
2CB9 - DME: Oxygen sensor 2 after catalytic converter: Signal fixed at Rich.

My car has downpipes so I'm not sure if that's what is causing this? So in essence the car seems to be maybe running rich which could be causing this high fuel consumption?

Busterboo
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z4 35i fuel consumption

Post by Busterboo » Sat Jan 13, 2018 12:16 pm

Presumably, your first next step will be to see how much your fuel consumption has improved after the de-carbonisation.
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sachak
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z4 35i fuel consumption

Post by sachak » Sat Jan 13, 2018 2:25 pm

so I spoke to a few people and found that because my car has no catalytic converters the o2 sensors after the cats which now sit on catless down pipes may be setting the mixture to rich which is causing the terrible fuel consumption.

So I just had catalytic converter foolers(mini cats) fitted to the car and hopefully this sorts the problem out. so far I haven't had the error come back. but the error is intermittent and usually only happens when I drive for a little while like on the motorway or something.

Will let you guys know what happens.

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z4 35i fuel consumption

Post by dhobbs » Sat Jan 13, 2018 2:35 pm

From what I've read, the coke build up is a result of oil seaping down from the valve stems and not the air intake. Seems to react with the metals of the engine.
This is only what I've read so please don't shoot me if you believe this is wrong.
As mentioned, fuel cleaner won't help and walnut blasting is the only option for now. But fuel cleaner may help with cleaning injectors and the exhaust sensors.

What's the milage required to do a walnut blast? Seems a service item now.
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sachak
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z4 35i fuel consumption

Post by sachak » Sat Jan 13, 2018 7:58 pm

dhobbs wrote: Sat Jan 13, 2018 2:35 pmFrom what I've read, the coke build up is a result of oil seaping down from the valve stems and not the air intake. Seems to react with the metals of the engine.
This is only what I've read so please don't shoot me if you believe this is wrong.
As mentioned, fuel cleaner won't help and walnut blasting is the only option for now. But fuel cleaner may help with cleaning injectors and the exhaust sensors.

What's the milage required to do a walnut blast? Seems a service item now.
Na that's definitely not the reason for the build up at all.

Here is a better explanation for you to read up on the reasons and all the details regarding carbon build up on direct injection engines.

https://www.bmwfanatics.co.za/showthread.php?tid=38980

with regards to how often. they say every 40k km. but for me I will be doing it every year at least.

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Nanu
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z4 35i fuel consumption

Post by Nanu » Sat Jan 13, 2018 9:24 pm

Smartbear wrote: Wed Jan 03, 2018 2:14 am
sachak wrote: Wed Jan 03, 2018 12:57 amok so it sounds like something is definitely wrong with the car.

Could this be due to a bad carbon build up around the valves? would a wall nut blasting remedy this problem?

What other things on these cars would typically cause this kind of bad consumption?
Hi, the biggest influence on mpg is driving style-I only have the 20i but you can see what’s possible with the right technique...
AC20460B-DCD4-48F8-90DE-B69296F5D8F8.jpeg
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Right technique??? I would be seriously worried about my driving technique if I was getting anywhere near the "average" MPG :evil:
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dhobbs
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z4 35i fuel consumption

Post by dhobbs » Sat Jan 13, 2018 9:25 pm

sachak wrote: Sat Jan 13, 2018 7:58 pm
dhobbs wrote: Sat Jan 13, 2018 2:35 pmFrom what I've read, the coke build up is a result of oil seaping down from the valve stems and not the air intake. Seems to react with the metals of the engine.
This is only what I've read so please don't shoot me if you believe this is wrong.
As mentioned, fuel cleaner won't help and walnut blasting is the only option for now. But fuel cleaner may help with cleaning injectors and the exhaust sensors.

What's the milage required to do a walnut blast? Seems a service item now.
Na that's definitely not the reason for the build up at all.

Here is a better explanation for you to read up on the reasons and all the details regarding carbon build up on direct injection engines.

https://www.bmwfanatics.co.za/showthread.php?tid=38980

with regards to how often. they say every 40k km. but for me I will be doing it every year at least.
http://www.oilem.com/turbo-fuel-stratif ... p-problem/

Here's where I read about it. I'll read your link now. Thankfully my car is not affected by this, but useful to know for my next car.
3.0si roadster. Requisite stubby. Sound gen mod. LED numberplate lights. LED boot strip. Interior lights LED too. ZHP gearknob. Daily drive :driving:
Motor in boot. Bilstein B8 dampers. New radio, much better sounds :thumbsup:

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z4 35i fuel consumption

Post by Busterboo » Sat Jan 13, 2018 9:36 pm

The OP seems no closer to finding why his fuel consumption's so poor.
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z4 35i fuel consumption

Post by step_change » Sun Jan 14, 2018 12:03 pm

From my E89 35is that I picked up last week I am getting about 27mpg. I think that is pretty darn good for a 3.0L twin turbo that is being driven "enthusiastically" :wink:
OP, there is something wrong, definitely.
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sachak
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z4 35i fuel consumption

Post by sachak » Sun Jan 14, 2018 1:28 pm

Guys and gals please don't tell me what your mpg is.
I can fool my car into giving me a ridiculously good MPG reading very easily. These things are stupid to read from which is why I originally said please don't tell me what your MPG/Liters per km readings are I am not too fussed about that. I want to know how many km or miles your getting to a full tank of fuel as that is real world data to me.

Thanks :)

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z4 35i fuel consumption

Post by step_change » Sun Jan 14, 2018 5:00 pm

The mpg average that people are telling you is real world data dude. 55 litre tank. The mpg is the determining factor as to what you get from a tank. THAT is the primary data point to work from, data we have shared with you. Do some multiplication or create a spread sheet and work it out.
Gone :( : 2013 35is, Melbourne Red, DCT, Nav, Comfort pack
Gone: 2007 2.5is, Montego Blue, Auto, Nav

sachak
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z4 35i fuel consumption

Post by sachak » Sun Jan 14, 2018 6:51 pm

All I am interested in is how many Km you get to a tank. I can reset my km/L setting while im on the highway and get a reading that is as good as a ford fiesta eco boost if I want its really easy.

I don't want to argue or come off the wrong way but seriously all I want is how many km/miles you got from when you filled the tank to when the reserve light switches on. EVERYTHING else is irrelevant to me at this stage.

Just to give you an example my car is reading 11.3 L/100km which is actually damn good for town driving and that equates to 31.92035 miles per gallon (Imperial) .....Trust me its a lie that I care very little about because what that thing says and what I get to a tank of fuel are two very different things. I have been able to fool every single BMW I have ever owned by resetting the trip meter while on the highway going down a hill and then letting it take the rest of the week to slowly creep up but never really getting to what the car is actually using. can prove this by using the app fuelly <-- that s**t is accurate. not the rubbish in our cars.

sorry to come off like that but honestly I asked for tank mileage for a reason so I can try get to the bottom of what these cars should actually average compared to what I am getting and I have tried many different styles of driving and tried different maps on the car with different setups.

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