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Causes of high fuel consumption. Updated 26Jan2007

Civic model year 1980 - 2000
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garilee
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Postby garilee » Sun May 02, 2010 9:27 am

Emperorcivic wrote:sohc got thermostat?
D-series and b-series thermostat are the same and compatible. sohc/d16 definitely will have thermostat
Version RR => Recon TypeR :butthead:

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graviti
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Postby graviti » Sat Nov 06, 2010 1:27 am

hi all,

i just gotten my EG6 last week and im wondering if my car is heavy on petrol..

i went on to the fuel station to pump a full tank of 95ron with a total of 33L+ which cost me ard 50++ bucks when my fuel meter hit the 'empty' mark but the refuel indicator haven light up(but i donno if it works anyway).. and i travel about 320km on the previous full tank which was pumped last saturday till to date..

my car is stock.. and im driving normally as in i didn't step very hard on the gas pedal.. jus wondering if its considered high fuel consumption?

pls advice..
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Postby YEN96 » Wed Nov 10, 2010 11:54 am

graviti wrote:hi all,

i just gotten my EG6 last week and im wondering if my car is heavy on petrol..

i went on to the fuel station to pump a full tank of 95ron with a total of 33L+ which cost me ard 50++ bucks when my fuel meter hit the 'empty' mark but the refuel indicator haven light up(but i donno if it works anyway).. and i travel about 320km on the previous full tank which was pumped last saturday till to date..

my car is stock.. and im driving normally as in i didn't step very hard on the gas pedal.. jus wondering if its considered high fuel consumption?

pls advice..


320km / 33L = about 10km/L ( maybe u drive short distance with a lot of stop ? )
Its about normal. however u should aim for 12km/L if your car is stock and light driving. 12km/L is very good fuel consumption

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Postby graviti » Thu Nov 11, 2010 12:20 am

thanks for the reply..

i think i do stop a lot for the traffic cos frm my hm to work place is short dist bout 4.9 km only but traffic light also a lot esp morning rush hour..

u did mention bout aiming 12km/l.. any idea how do i work through it?

sorry on the noob question..
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Postby takumi84 » Mon Nov 15, 2010 1:09 am

1) use better petrol
2) mayb it the way u drive
3) try to lighten ur car weight
4) type of tire and tire pressure
5) mayb air filter dirty?
and etc

i can clock 12+km/l with V power
but 10+km/l for 98...

So there are really alot of variation factors...

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Postby Will_SG » Fri Nov 19, 2010 7:13 pm

takumi84 wrote:1) use better petrol
2) mayb it the way u drive
3) try to lighten ur car weight
4) type of tire and tire pressure
5) mayb air filter dirty?
and etc

i can clock 12+km/l with V power
but 10+km/l for 98...

So there are really alot of variation factors...


I got the best milage from Caltex techron 12.5 KM/L. V-Power and shell 98 gives me the worst milage is about 11.5 KM/L.

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Postby optimusprime_10 » Fri Nov 26, 2010 10:33 am

graviti wrote:thanks for the reply..

i think i do stop a lot for the traffic cos frm my hm to work place is short dist bout 4.9 km only but traffic light also a lot esp morning rush hour..

u did mention bout aiming 12km/l.. any idea how do i work through it?

sorry on the noob question..


u driving M or A/T?

i think it depends on expressways/ roads with traffic lights..

i can hit 12km/L if 85% on expressways.. less stops..

n traffic jams can waste fuel too..

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Re: Causes of high fuel consumption. Updated 26Jan2007

Postby jansonfinn » Thu Dec 06, 2012 6:41 pm

garilee wrote:Juz help share some tips for every1 to identify and solve your high fuel consumption problems:

A) Faulty O2 sensor (common problem)
This is connect to yr exhaust manifold and detects the engine air/fuel ratio. It will feedback to yr ecu to adjust yr fuel map.. so if it detects lean a/f, ecu add more fuel. If it detects rich a/f, ecu deduct fuel to yr engine. So this sensor is VERY IMPORTANT for good fuel consumption! This sensor got wear & tear also and expected life is abt 50,000km to 100,000km. when the sensor starts to die, it usually signal low voltage to the ecu and ecu automatically keeps adding fuel to yr engine. 2nd sensors can be bought at scrap yards for $50-70 but u take the risk if the sensors are faulty. New ones costs more than $200. ESI and DOHC sensors are compatible but the DOHC sensors design seems more durable.
An easy way to identify this prob is to reset yr ecu by removing the 15A fuse from the fuse box under yr bonnet. This will erase the ecu memory and reset back to factory settings. If its confirm O2 sensor prob, yr car will run better and slowly worsen as the O2 sensor starts feedback to the ecu.

B) Faulty coolant temperature sensor (usually common in wet weather)
This is connect to yr engine header to detects the engine temperature. It will feedback to yr ecu to adjust yr fuel map.. if it detects temperature below 80degrees, ecu add more fuel. i havent heard much people change this sensor coz in most times, we are worried more on overheating prob than colder temp. But it can be a prob with fuel consumption when the weather is cold. Mine went haywire recently and i detected it thru a digital meter.. bought a new piece at less than $30 fr Tanly.
Unless u have a digital water temp gauge connected to this sensor, it is quite difficult to detect this prob

C) Faulty fan switch/ fan main relay / fan switch set to direct(usually common in wet weather)
The fan switch is connect just beside the thermostat housing to detect the coolant temperature. if it detects temperature above the fan switch temp (different fan switch have diff operating temp, like mugen ones which activate at abt 80+ degees versus stock ones at 90+ degrees), the radiator fan activates to cool the radiator. faulty fan/ main relay/ fan set to direct on have the same effect as (B) above. It can cause the coolant temp sensor to detect low temp, resulting in ecu adding fuel to the engine. By the way, for those with relay failure, i found a shop at King georges that sell the relay for only $7 per piece compare to abt $20 at stockists.
The easiest way to find out if it is relay prob is to use a multi meter to test the socket of the fan switch with ignition on. For the fan switch itself, have to remove and soak the sensor part in hot water and use multi meter test the points. another obvious sign is the fan turns on immediately when u turn on yr ignition

D) Leaking exhaust extractor
Have came across cases where the connecting point of the exhaust extractor can crack, there is gasket leak and those bros that weld 2 bolts to the extractor to reuse stock cover broke with a hole in the piping (common to 4-2-1 or 4-1 aftermarket extractors). This can coz the engine to lose compression and poor fuel combustion.. u end up with much higher fuel consumption.
check for signs of cracks or holes in the extractor. With the engine running, u may hear slight hissing sound or air pressure from the leaking area. welding works to mend holes & cracks usually not much

E) Foul spark plugs
Spark plugs can foul (or drown) when the plugs are too cold for yr engine set-up. The most common prob is ur engine a/f ratio is too rich and usually happen if u mod or touch anything on yr fuel system like fuel regulator pressure too high, injectors too big etc. See (F).
juz remove all yr plugs and check. If its covered with black carbon, u have to change new spark plugs and retify the problem in ur fuel system

F) Fuel system
Injectors can spoil or get dirty, injectors too big, fuel pressure regulator set too high, fuel pump too big for yr set-up.. these can cause rich a/f ratio if yr engine is not properly tuned.

G) Running without a thermostat
Same as (B) and (C)

H) Engine tuned by tuner with faulty/inaccurate lambda sensor
This 1 beri obvious rite? Poor tuning due to rich a/f ratio by tuner definitely high fuel consumption lor.

I) Faulty main fuel relay (COMMON PROBLEM)
This main relay controls the power to yr fuel pump, injectors, ecu, distributor and wear & tear of the relay can coz inconsistent power supplied to any of the components, the most common being difficulty in starting car.
it doesnt hurt to change a new relay to be safe coz it only costs abt $35 considering the significant control this relay has on the key components of yr car

J) Faulty distributor
The distributor is the main component in firing up yr plugs. the common wear & tear occurs at the coil, rotor and igniter. weak coil=weak voltage to power up the spark plugs to ignite. faulty igniter can coz wrong firing of the spark plugs and worn rotor=improper distribution of the voltage to the 4 spark plug wires. The common signs are significant poor fuel consumption and occasional engine jerking especially when engine under load.
there is standard wear & tear in these parts and it is not easy to diagnose the actual problem. it is advisable to change all 3 components together

K) unhealthy engine-internal
Engine with worn valve seals and/or worn piston rings causes low engine compression (similiar to (D)). U usually get lots of blackish smoke when u go WOT or high engine revs. also makes yr car lose engine oil
Can do engine compression test and leakdown test to confirm

L) leaking engine head gasket
Leaking head gasket cause the same problem of low engine compression (see (D)). On top of that, coolant could leak into the combustion chamber and create low engine temp (similiar to (B)). In addition, unburnt coolant would escape through the exhasut extractor and over time, it could contaminate your O2 sensor (see (A)) and kill it.
usually visible oil leaks at the edge of the engine head and brownish/murky color deposits in the radiator. for slight leaks, u will notice bubbles in the coolant with the radiator cap off & engine running

M) Faulty air intake temperature sensor
This is connect at the side of yr intake manifold to detects air temp flowing into the engine. It will feedback to yr ecu to adjust yr fuel map.. if it detects cold temperature, ecu add more fuel. seldom hear this sensor will spoil but it can be a prob with fuel consumption if it starts reading low voltage even when intake air is warm.. creating rich a/f ratio
Unless u have a digital air temp gauge connected to this sensor, it is quite difficult to detect this prob

N) Faulty ECU (quite common these days)
This 1 also obvious answer coz its the brain of the whole car. Furthermore, most of the civics already more than 10 years old.. can imagine how old the ecu is?? Its electronics and electronics got lifespan. only a matter of time before it dies.. juz like a motherboard of a computer.
My ultimate recommendation.. save $ and get a standalone if u intend to keep the car long. If not, juz wait for the dreadful day to come..

O) Tyres:low pressure, performance tyres and bigger tyres
Low yr tyre pressure, performance tyres and biiger tyres all give u more grip on the road surface creating friction=more energy required to move the car=higher fuel consumption.
make sure yr tyre are properly inflated, dun use high grade tyres if u dun have the applications for it and stick to 15" rims

P) Weight
Heavy car=more load=more energy to push=more fuel required. Simple rite? thats why u see fast cars using carbon fibre and fibre bonnets etc.
dump anything that u dun need in the car. THIS IS THE NO.1 WAY TO MOD A CAR.. PERIOD!! and its free.. unless u try to be innovative using plastic windows

Q) jammed brake caliper
brake calipers also need servicing.. if too much dirt and debris get stuck to the brake pistons, it can get jam.. thats when ur engine have to work hard to push the extra load created by the braking
jack car up and roll wheels to check lor

R) worn injector seals
injector seals are made of rubber and over time, with the heat of the engine compartment, it might wear off.
yellow stains on the intake manifold where the injectors are installed and smell of fresh fuel

S) distributor adjusted too retarded
distributors can be shifted to adjust the engine's ignition timing=timing of firing of the spark plugs. This is a VERY IMPORTANT area becoz it affects ignition and engine relies on proper a/f ratio and ignition timing to run properly. if distributor adjusted too retard, there wont be enough ignition to burn fuel properly=richer a/f ratio. If distributer adjusted too advance, u risk engine knocking=engine damage.
best to let wkshop or experienced ppl to check for u. Coz u dun want to adjust wrongly and cause serious engine damage

T) insufficient engine grounding
based on my own experience while tuning my car, i realised slight electrical surges and fluctuations that affects the a/f ratio and rpm readings. i suspected poor grounding and after i added some grounding wires to the distributor and intake manifold area.. it actually solves the prob. Interesting fact to justify adding grounding wires to the engine bay. Up to u to believe me though..
try to ground components where there are electrical flows like distributor, alternator, intake manifold etc. anyway, if no $, can also use cheap wires to ground.. it serves the same effect anyway

U) faulty MAP sensor (COMMON PROBLEM)
MAP sensor is mounted just above the throttle body (older design throttle bodies like d15b have it mounted separately on the engine bay firewall). Faulty map sensor creates inconsistent signals to engine ecu and results in inconsistent a/f ratio..
the only way to detect is when yr car starts having inconsistent performce like running rich 1day and going lean the next day.. i found out thru inconsistent readings fr my lambda sensor.. after changing the map sensor.. a/f ratio returns back consistent

ANY1 ELSE WANT TO ADD ON MORE INFO?? PLS DO SO..

I suspect my EG6 is facing both problems A & C. Having FC for abt 8-9Km/l

(A) is because after letting go of my acceralator, the car voltage will drop till 10 or 11v. But once u apply the acceralator, the voltage went back to 14v.

(C) is because my fan is always on the moment I switch on my ignition. All the socket is connected, so not a direct connect case. Should be a faulty relay.

Question is which part of king George to get the relay? Anyone got the full address or at least the shop name so that I can go there & find?


Thanks

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Will_SG
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Re: Causes of high fuel consumption. Updated 26Jan2007

Postby Will_SG » Sat Dec 08, 2012 11:18 am

jansonfinn wrote:I suspect my EG6 is facing both problems A & C. Having FC for abt 8-9Km/l

(A) is because after letting go of my acceralator, the car voltage will drop till 10 or 11v. But once u apply the acceralator, the voltage went back to 14v.

(C) is because my fan is always on the moment I switch on my ignition. All the socket is connected, so not a direct connect case. Should be a faulty relay.

Question is which part of king George to get the relay? Anyone got the full address or at least the shop name so that I can go there & find?


Thanks


one of the shop at king George's building. They display the relay outside.


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