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Location: Sydney
Registered: October 2003
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AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 03:18
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Hey all
got a bigport in the AE86 - installed it with an external vl turbo pump and standard lines (smaller one for return line) ect
it seems to be running hell rich- response and power is good so its not bogging down but fuel consumption is rediculous (before you ask i dont thrash it on the rev limiter every gear so its not my driving style)
im finding i average about 260-280 k's to a tank of ultimate- it uses more fuel than my 2L turbo 180sx
i always keep it over 1/4 tank as i dont have an intank setup/baffles ect but it goes through fuel like its going out of style
Can anyone compare this with similar setups
Also if it makes a difference im running a jap spec ecu- but dobut that would account for much
any advice is mucho apreciated
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Registered: May 2002
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Location: Sydney NSW
Registered: July 2004
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 04:17

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My Bigport (MAP sensor) gets pretty average economy, but not that bad. I will use about 35 litres over 300k's. Mind you, i havnt had a good look at the setup on mine yet. It seems to be a "chipped" JDM ECU, but i suspect its running in safety mode most of the time. Runs hella rich when its cold too.
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Location: Sydney
Registered: October 2003
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 06:00

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yeah man 40 litres gets 300k's = wtf
I was expecting to get 5-600k's easy on a tank- my car is standard cept for a k&N panel filter in the jdm airbox and its costing me a lot to keep it on the road-
this is my daily so want it to be econmical- turns out my worked 180sx has double the economy which is totally whack
any ideas fellas?
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Registered: May 2002
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 06:10

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Use the diagnostic port and see if it spits out an error code, that will be the simplest way to find the problem. A quick search of this forum will find you instructions on how to use the diagnostic port and what the error codes mean.
Sounds like your ECU is over fuelling and it is most likely due to a dead sensor or poor connection to the sensor or........a fuel leak
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Location: Brisbane
Registered: February 2003
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 06:39

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Maybe you arent really running it down to a 1/4tank, because the fuel level sender is not functioning correctly?
How are you working out the fuel consumption?
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Location: Sydney
Registered: October 2003
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 06:44

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fuel level sender MAY be buggy though i am putting in a good 20-30 litres and getting only 200 odd k's out of it- dont really want to risk driving with the meter on empty
Will run a diagnostics check tonight- will search for which pinouts to bridge on the port
def not a fuel leak- and taken a bit of weight from the car--ripped out all air conditioning crap ect
which would be a crucial sensor that would overfuel like that- if i can pinpoint it i will take it apart and clean it
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Location: Sydney NSW
Registered: July 2004
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 07:03

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Best way to figure fuel consumption is to always fill it to the same level (full to first "click"), and zero your trip meter at the same time. Then every fill up after that you just look at the trip meter and the fuel reading on the bowser and voila.
Never trust a fuel guage, they would be more accurate if you used them as a compass.
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Location: Adelaide
Registered: August 2003
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 07:21

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That fuel economy isnt right at all.
I get about 350km for 30litre. Thats on a bigport which is ported with lumpier cams. Pretty hard driving too..
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Location: NSW, East Coast
Registered: July 2003
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 07:51

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I have jdm bigport, pod, full exhaust, no speed sensor. 50/50 highway/city driving, moderate driving style i guess, usually 550kms before i fil up
ultimate all the way.
CHeers
Steve
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Location: Castle Hill
Registered: August 2003
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Re: AE86 4age- bigport fuel consumption
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Mon, 11 July 2005 12:36

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I am having the exact same problem with my Sprinter...
AE82 bigport, RWD intake, K&N Pod filter, Extractors and JDM ECU.
I get 180-200kms to a tank, and it doesn't seem to change much wether all my gear changes are at 3k or 7k!!
Is yours chewing oil and coolant aswell?
Even when I run my AUS ECU this doesn't change one bit!
Please keep this thread updated if you find out any solutions and please post the results of your diagnostics test!
If I ever fix mine I will chuck up the solution in here too!
Cheers.
-Whitchy-
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Location: Melbourne
Registered: May 2002
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Re: AE86 4age- bigport fuel consumption
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Tue, 12 July 2005 00:54

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they're map sensored right?
is the map sensor hooked up and working properly?
this might sound stupid, but if it's using a different map sensor, and the plugs have been adapted, (i.e. a new map sensor connecting to the older style plug of the ae86) maybe someone crossed the feed and signal wire? that could explain it!.. would run fine on open thorttle but go through a lot of fuel during normal driving 
sounds like some kind of map sensor leak or something like that..
maybe it's getting the wrong signal for how much air is in the manifold (map) maybe there's a bad connection in a wire along there.. dunno..
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Location: Adelaide
Registered: July 2002
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Re: AE86 4age- bigport fuel consumption
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Tue, 12 July 2005 01:44

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exhaust 02 sensor
i had this fail on my smallport and the economy went to shit ie less than 300kms out of 30 litres
put in an o2 sensor from a camry, all i culd find, and backup and running with 7L/100km economy for daily city drivin 
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I supported Toymods
Location: melbourne
Registered: June 2002
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Re: AE86 4age- bigport fuel consumption
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Tue, 12 July 2005 02:43

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my fuel economy isnt great, getting roughly 13 litres per 100 city driving.
i dont have a air temperature sensor, and my oxy sensor isnt hooked up,
i'd check all your sensors, if you have them all.
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Location: Sydney NSW
Registered: July 2004
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Re: AE86 4age- bigport fuel consumption
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Tue, 12 July 2005 03:28

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Yeah, i forgot to say, mine doesnt have an oxy sensor
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Location: Sydney
Registered: October 2003
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Re: AE86 4age- bigport fuel consumption
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Tue, 12 July 2005 05:45

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kk bit more info
this is not some ae82 engine converted to rwd
This came from japan from an early ae86 trueno
All the looms were uncut so just plug and play -no messing around
i fit the 02 sensor and it didnt seem too bad though if that could be it ill deff change it
other than that where can i find the map sensor?
With fuel prices nearing $1.30 a litre- i want to fix this bastard-under 300 a tank is a bitch- and as whitchy says doesnt matter if i shift at 3 grand or redline every gear- fuel consumption is the same
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Location: Sydney NSW
Registered: July 2004
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Re: AE86 4age- bigport fuel consumption
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Tue, 12 July 2005 06:11
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The Map sensor is on the firewall (or it should be) above the intake side rocker cover. It is a square black thing, with an electrical lead with a round plug (probably yellow if its JDM, but someone will correct me if i'm wrong) and a small vacuum hose connecting it to the intake plenum (i think approx 1/3 of the way back, on the engine side of the plenum)
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