300Km To A Tank... What The Hell? R33 Gts-T

[tripsteady]

Hey Guys

I own a 1997 R33 GTST S2. Recently had a oppurtunity to fill up the tank and reset the km's

Tank is now empty and Ive done 300km! That is terrible economy. I know its a skyline and i didnt buy it for its thriftiness of fuel but 300km?

Ive heard people doing 450-500 on a tank , this seems to thirsty for me

- Done the 100k service

- Replaced fuel filter

- Replaced o2 sensor

- Havnt been flogging it

What else could cause my economy to be this bad even after I have done the above?

[blind_elk]

The only way you can determine fuel economy is to refill the fuel tank and note the litres used. Just saying "the tank is empty" means nothing.

City driving and short trips will adversely affect fuel economy. A dead temp sensor won't help either.

[tripsteady]

litres used --> 65L

Kmsdone 300

Stock ecu

only engine mods are pod filter , stock boost , and 3inch exhaust straight through with gtr cat and 3inch hks front pipe

stock boost is around 5spi before 3500 and 7psi after.

Tank is 65Ltrs and it cost me $75 to fill up @ $1.51 for 98 octane

[blind_elk]

$75 @ $1.51 is only 49.7 litres. Over 300km, that equates to 16.5l/100km (approx 6km/l). On 65 litres tank capacity, you should get a bee's dick over 400km on a tank.

[mad082]

$75 @ $1.51 is only 49.7 litres. Over 300km, that equates to 16.5l/100km (approx 6km/l). On 65 litres tank capacity, you should get a bee's dick over 400km on a tank.

this is exactly why people using "a tank" as a unit of measurement shouldn't be allowed to start fuel economy threads. every second idiot who starts one pays no attention to how much fuel they are putting in, only how many kms they are doing before they fill up, so they have no idea what sort of economy they are actually getting.

in this case, what do you call "not flogging it"? are you regularly hitting boost even if not completely flooring it? if yes, then lay off the throttle a bit. how long does the car take to come up to temp? the temp needle should get to the middle of the gauge after a matter of minutes of driving. if it takes longer, or never gets to the middle of the gauge, you need a new thermostat. and if you are one of those people who let the car idle for a few mins to warm up before you drive it anywhere, well that won't be helping your fuel economy. maybe also check your tyre pressures.

if you want better economy, go easy on the throttle. fuel economy isn't about how low in the rev range you change gears, but how light you are on the throttle. try driving around and stay off boost as much as possible. it's not hard to do. you should easily be able to drive around without hitting positive boost. also, if you are coming up to a set of lights that are red, lift off and coast from a long way back. basically, if you have to use your brakes approaching an intersection, you're wasting fuel, if you get what i'm saying. also, if there are a few sets of lights one after another, not too far apart and only the first one turns green, there is no need to rush up to 60kmh only to have to get hard on the brakes again. you will use much less fuel if you drive like a truckie. coast up to intersections with the aim of not coming to a complete stop. coming to a complete stop means you have to use extra fuel to get the car moving again.

[tripsteady]

this is exactly why people using "a tank" as a unit of measurement shouldn't be allowed to start fuel economy threads. every second idiot who starts one pays no attention to how much fuel they are putting in, only how many kms they are doing before they fill up, so they have no idea what sort of economy they are actually getting.

in this case, what do you call "not flogging it"? are you regularly hitting boost even if not completely flooring it? if yes, then lay off the throttle a bit. how long does the car take to come up to temp? the temp needle should get to the middle of the gauge after a matter of minutes of driving. if it takes longer, or never gets to the middle of the gauge, you need a new thermostat. and if you are one of those people who let the car idle for a few mins to warm up before you drive it anywhere, well that won't be helping your fuel economy. maybe also check your tyre pressures.

if you want better economy, go easy on the throttle. fuel economy isn't about how low in the rev range you change gears, but how light you are on the throttle. try driving around and stay off boost as much as possible. it's not hard to do. you should easily be able to drive around without hitting positive boost. also, if you are coming up to a set of lights that are red, lift off and coast from a long way back. basically, if you have to use your brakes approaching an intersection, you're wasting fuel, if you get what i'm saying. also, if there are a few sets of lights one after another, not too far apart and only the first one turns green, there is no need to rush up to 60kmh only to have to get hard on the brakes again. you will use much less fuel if you drive like a truckie. coast up to intersections with the aim of not coming to a complete stop. coming to a complete stop means you have to use extra fuel to get the car moving again.

thanks for all the tips although certainly did nnot appreciate being called an idiot or the air of superiority in which it was said.

I was under the impression that the skyline had a 65L tank , yes I know the maths doest make sense but i filled up until I couldnt hold the pump down anymore as it was flicking back up and according to the fuel guage it was all the way to the top(a few mm above full)

assumed this was what the skyline could hold.

I dont see the point in driving a skyline and having to coast everywhere and avoid boost however I have been keeping my eye on the boost guage to make sure I dont go above positive boost.

Filled another $30 at 1.61 a litre , did another 120km and the tank is empty once again

car takes about 15min on idle and about 3min while driving to come up to temp , only let it idle for about 2min before I drive though.others have suggested resetting my ecu and getting it tuned.

WIll also note that my car is jerking at WOT because of the coilpacks , this couldnt be raising my fuel consumption as well could it?

In any case I am planning on tuning it after I install the intercooler.

[blind_elk]

I was under the impression that the skyline had a 65L tank , yes I know the maths doest make sense but i filled up until I couldnt hold the pump down anymore as it was flicking back up and according to the fuel guage it was all the way to the top(a few mm above full)

assumed this was what the skyline could hold.

Yes it's 65L capacity, but that doesn't mean every time you fill it you have added 65L! The fuel gauge is indicative only, means absolutely diddly squat as a measuring device. Get the "litres added" from the petrol pump display.

Filled another $30 at 1.61 a litre , did another 120km and the tank is empty once again

= 18.6 litres @ 15.5l/100km. Actually what you are saying is not clear. You have to do the distance BEFORE you add the fuel. Then you can accurately calculate fuel economy. As above, do not rely on the fuel gauge to tell you exactly how much fuel has been used or how much remains in the tank. Only the petrol pump can tell you how much fuel goes into the tank AFTER you have done some kms. The only accurate part of the gauge appears to be the "low fuel" warning lamp, which will come on at around 10-15 litres remaining (exact turn on point appears to differ car to car).

car takes about 15min on idle and about 3min while driving to come up to temp , only let it idle for about 2min before I drive though.others have suggested resetting my ecu and getting it tuned.

30 seconds is all the idle from startup that is required. That's basically long enough to put on your seat belt and select a gear. You can save 25 of those by buckling up before you even start the engine. Extended idling from cold start wastes fuel and increases damage to the engine. Just be sensible about driving a cold engine - limit revs to 3k, maybe 4k, STAY OFF BOOST.

WIll also note that my car is jerking at WOT because of the coilpacks , this couldnt be raising my fuel consumption as well could it?

Of course it's raising fuel consumption. The jerking is because the fuel is not being burned properly, and you are spitting raw fuel out the exhaust. (and last time I considered it, WOT amounted to "flogging it")

In any case I am planning on tuning it after I install the intercooler.

Unless you have an aftermarket ECU, you can't tune R33 ECUs.

[Cowboy1600]

Your coilpacks won't be helping.

Do this.

Fill tank to the first click of the pump nozzle

Reset trip meter

Drive till "empty" - as in you hit the bottom of the fuel gauge not until the car actually stops

Go to servo

Fill tank to full (one click again)

Take note of how many litres you added

Divide litres by distance travelled in kilometers and multiply by 100 - ie, (49 litres / 387 kilometers) *100 = 12.66l per 100ks.

If you get anything south of 15 with an RB, you're doing OK, however new coilpacks will improve it.

I also found that resetting my ECU improved things in my R33. To do this, disconnect your battery then hold your foot on the brake for 30 seconds. This will discharge all of the residual power out of your car. Reconnect the battery and drive the car around for 30 minutes being very gentle. R33 ECUs (like most cars) have a tiny amount of self-adjustablility and will actually "learn" what kind of driving you do and adjust accordingly. So if you drive like a pussy, it'll learn to be frugal. Note, the range over which it can "self-adjust" is very small.

[tripsteady]

Yes it's 65L capacity, but that doesn't mean every time you fill it you have added 65L! The fuel gauge is indicative only, means absolutely diddly squat as a measuring device. Get the "litres added" from the petrol pump display.

= 18.6 litres @ 15.5l/100km. Actually what you are saying is not clear. You have to do the distance BEFORE you add the fuel. Then you can accurately calculate fuel economy. As above, do not rely on the fuel gauge to tell you exactly how much fuel has been used or how much remains in the tank. Only the petrol pump can tell you how much fuel goes into the tank AFTER you have done some kms. The only accurate part of the gauge appears to be the "low fuel" warning lamp, which will come on at around 10-15 litres remaining (exact turn on point appears to differ car to car).

30 seconds is all the idle from startup that is required. That's basically long enough to put on your seat belt and select a gear. You can save 25 of those by buckling up before you even start the engine. Extended idling from cold start wastes fuel and increases damage to the engine. Just be sensible about driving a cold engine - limit revs to 3k, maybe 4k, STAY OFF BOOST.

Of course it's raising fuel consumption. The jerking is because the fuel is not being burned properly, and you are spitting raw fuel out the exhaust. (and last time I considered it, WOT amounted to "flogging it")

Unless you have an aftermarket ECU, you can't tune R33 ECUs.

Your coilpacks won't be helping.

Do this.

Fill tank to the first click of the pump nozzle

Reset trip meter

Drive till "empty" - as in you hit the bottom of the fuel gauge not until the car actually stops

Go to servo

Fill tank to full (one click again)

Take note of how many litres you added

Divide litres by distance travelled in kilometers and multiply by 100 - ie, (49 litres / 387 kilometers) *100 = 12.66l per 100ks.

If you get anything south of 15 with an RB, you're doing OK, however new coilpacks will improve it.

I also found that resetting my ECU improved things in my R33. To do this, disconnect your battery then hold your foot on the brake for 30 seconds. This will discharge all of the residual power out of your car. Reconnect the battery and drive the car around for 30 minutes being very gentle. R33 ECUs (like most cars) have a tiny amount of self-adjustablility and will actually "learn" what kind of driving you do and adjust accordingly. So if you drive like a pussy, it'll learn to be frugal. Note, the range over which it can "self-adjust" is very small.

excellent advice guys , excuse my extreme ignorance. Will follow above advice and post results.

[mad082]

thanks for all the tips although certainly did nnot appreciate being called an idiot or the air of superiority in which it was said.

I was under the impression that the skyline had a 65L tank , yes I know the maths doest make sense but i filled up until I couldnt hold the pump down anymore as it was flicking back up and according to the fuel guage it was all the way to the top(a few mm above full)

assumed this was what the skyline could hold.

I dont see the point in driving a skyline and having to coast everywhere and avoid boost however I have been keeping my eye on the boost guage to make sure I dont go above positive boost.

Filled another $30 at 1.61 a litre , did another 120km and the tank is empty once again

car takes about 15min on idle and about 3min while driving to come up to temp , only let it idle for about 2min before I drive though.others have suggested resetting my ecu and getting it tuned.

WIll also note that my car is jerking at WOT because of the coilpacks , this couldnt be raising my fuel consumption as well could it?

In any case I am planning on tuning it after I install the intercooler.

wasn't neccessarily calling you specifically an idiot, more just saying the people who don't pay attention to how much fuel they put in when trying to calculate fuel economy are very much missing the point of the excercise. and given that there have been hundreds of fuel economy threads over the years, and the majority have people using "a tank" as the unit of measure, it does get quite annoying.

and yes, the skyline tank is 65L. that is 65L when bone dry, in other words, once the car has stalled and won't restart. even then it probably has a small amount of fuel in the bottom of the tank which the pump hasn't picked up. this just makes up for the amount of fuel that the filler neck holds.

but if you are worried about fuel economy, a skyline is not for you. they are not economical at the best of times.

Yes it's 65L capacity, but that doesn't mean every time you fill it you have added 65L! The fuel gauge is indicative only, means absolutely diddly squat as a measuring device. Get the "litres added" from the petrol pump display.

= 18.6 litres @ 15.5l/100km. Actually what you are saying is not clear. You have to do the distance BEFORE you add the fuel. Then you can accurately calculate fuel economy. As above, do not rely on the fuel gauge to tell you exactly how much fuel has been used or how much remains in the tank. Only the petrol pump can tell you how much fuel goes into the tank AFTER you have done some kms. The only accurate part of the gauge appears to be the "low fuel" warning lamp, which will come on at around 10-15 litres remaining (exact turn on point appears to differ car to car).

30 seconds is all the idle from startup that is required. That's basically long enough to put on your seat belt and select a gear. You can save 25 of those by buckling up before you even start the engine. Extended idling from cold start wastes fuel and increases damage to the engine. Just be sensible about driving a cold engine - limit revs to 3k, maybe 4k, STAY OFF BOOST.

Of course it's raising fuel consumption. The jerking is because the fuel is not being burned properly, and you are spitting raw fuel out the exhaust. (and last time I considered it, WOT amounted to "flogging it")

Unless you have an aftermarket ECU, you can't tune R33 ECUs.

yep, extra idle time just wastes fuel and increases engine wear.

yes, fuel light generally means 10 to 15L of fuel left.

and yeah, generally speaking, WOT is considered flogging it.

Your coilpacks won't be helping.

Do this.

Fill tank to the first click of the pump nozzle

Reset trip meter

Drive till "empty" - as in you hit the bottom of the fuel gauge not until the car actually stops

Go to servo

Fill tank to full (one click again)

Take note of how many litres you added

Divide litres by distance travelled in kilometers and multiply by 100 - ie, (49 litres / 387 kilometers) *100 = 12.66l per 100ks.

If you get anything south of 15 with an RB, you're doing OK, however new coilpacks will improve it.

I also found that resetting my ECU improved things in my R33. To do this, disconnect your battery then hold your foot on the brake for 30 seconds. This will discharge all of the residual power out of your car. Reconnect the battery and drive the car around for 30 minutes being very gentle. R33 ECUs (like most cars) have a tiny amount of self-adjustablility and will actually "learn" what kind of driving you do and adjust accordingly. So if you drive like a pussy, it'll learn to be frugal. Note, the range over which it can "self-adjust" is very small.

you don't have to drive until empty. just drive a few hundred kms and then fill up.

the other thing to note is that it is best to fill up at the same servo, using the same pump is possible. and only fill up until the first click, or if you go an extra click or 2, do that again the next time you fill up. this way you are getting an even sample. i know that between 2 servos that i regularly get fuel from, they vary by a few litres from when they click off. i know this because from one servo i get 1.5 trips to and from work to the first 1/4 of a tank, but from the other i get 2 trips to and from work (it's a 125km round trip to work and back). and this is reflected in the fuel economy when i change between the 2 servos for the first fill up. one gives better than average, the other gives worse.

[tripsteady]

Ok so filled $30 , noted it said 19.62 ltrs filled. Drove around and didnt hit positive boost at all(basically drove like a granny)

Ive done 180km and the light has come on.

to reiterate, mst of it was stop start driving with the occasional highway.

i didnt fill it all the way up as i know the fuel gauge is deceiving(in any case needle rose to under the halfway mark with $30(19.62 litrs in from empty) , so i took note of the litres used and didnt really worry about the fuel tank until the light came on (verified that it can do 15km more once light is one until completely out).

so in other words the most important info here is 19.62Ltrs = 180km of driving while driving in stop start traffic without hitting positive boost.

Should I be worried that something is up?

reset my ecu today , will fill up again and see how it goes.

Edited November 11, 2012 by tripsteady

[blind_elk]

19.62 litres is not "half a tank". (when I went to school, half of 65 was 32.5, not 19.6). You have been previously told that the gauge is useless for indicating an exact amount of fuel in the tank. I've actually had my low fuel light on when the gauge said full, or half, or two thirds, because the gauge is worn and what it indicates varies enormously. Although it never seems to indicate less fuel than is available.

YOU HAVE TO FILL THE TANK! That is the only point at which you know the exact fuel level. Add some fuel then drive around until the low fuel light comes on doesn't mean anything. What the fuel gauge says isn't worth much of a cracker in this exercise.

And you need to zero/reset the trip meter.

So, you FILL THE TANK and reset the trip meter, drive around for a while, then FILL THE TANK. Note the litres required to FILL THE TANK, and divide that number into (kms on the trip meter x 100). Reset the trip meter again.

[260tech]

19.62 litres is not "half a tank". (when I went to school, half of 65 was 32.5, not 19.6). You have been previously told that the gauge is useless for indicating an exact amount of fuel in the tank. I've actually had my low fuel light on when the gauge said full, or half, or two thirds, because the gauge is worn and what it indicates varies enormously. Although it never seems to indicate less fuel than is available.

YOU HAVE TO FILL THE TANK! That is the only point at which you know the exact fuel level. Add some fuel then drive around until the low fuel light comes on doesn't mean anything. What the fuel gauge says isn't worth much of a cracker in this exercise.

And you need to zero/reset the trip meter.

So, you FILL THE TANK and reset the trip meter, drive around for a while, then FILL THE TANK. Note the litres required to FILL THE TANK, and divide that number into (kms on the trip meter x 100). Reset the trip meter again.

There it is.

[tripsteady]

okay ...understood , wasnt really looking at the fuel guage as an indicator since i wanted to see how many km's i would get per a certain Ltr of petrol and was told that while the fuel guage was useless , it did at least accurately display about 15km worth of normal driving when the low fuel light came on.

I dont really care about the fuel level and all i wanted to see was how many km's my 19.62 LTRS of fuel gave me, I therefore thought x Ltrs = x KM would give me an approx of how many km's i am able to get per litre...that is all

waiting for prices to go down before I fill all the way up(as we all know the prices vary differently dependant on the day of the week)

[mad082]

facepalm......

you cannot just put some random amount of fuel in, drive around and then put some other random amount of fuel in and then work out your economy from that. you might as well have just had a 4 year old kid also do the calculations for you in their head. the number they would give you would be about as accurate as your numbers.

the whole point of filling the tank to the top before starting off is so that you can fill it up to the exact amount of fuel you have used. that is why i also said in a previous post about trying to use the same servo, and ultimately the same pump at that servo and then only filling until the first click both times you fill up. this way you can garantee that there will be a minimal difference between before and after volumes.

had your figures been accurate in anyway, your fuel economy would've been around 11L/100kms, which is retty good.

[zoomzoom]

I really didnt want to chip in because reading "X kms to a tank" really shits me to tears, and usually results in an estimate of 20+ litres of fuel per 100km...Anyhow, either do the instructions that cowboy1600 lists and then bring us the numbers, or don't bother at all. No other estimates are going to be of use.

I would however add a few things. Once the pump clicks out the first time I usually wait 10 seconds then add more slowly until the second click just in case it cut out early. Ive had it happen.

Secondly, Ive had better results not avoiding boost. I have a auto stagea, which is also heavier than skylines. I had consistently worse fuel economy by disabling 4th/overdrive and avoiding boost. Try using less revs and more boost, thats the whole point of a turbocharger. Why buy a turbo car and not use it? YMMV.

[mad082]

I really didnt want to chip in because reading "X kms to a tank" really shits me to tears, and usually results in an estimate of 20+ litres of fuel per 100km...Anyhow, either do the instructions that cowboy1600 lists and then bring us the numbers, or don't bother at all. No other estimates are going to be of use.

I would however add a few things. Once the pump clicks out the first time I usually wait 10 seconds then add more slowly until the second click just in case it cut out early. Ive had it happen.

Secondly, Ive had better results not avoiding boost. I have a auto stagea, which is also heavier than skylines. I had consistently worse fuel economy by disabling 4th/overdrive and avoiding boost. Try using less revs and more boost, thats the whole point of a turbocharger. Why buy a turbo car and not use it? YMMV.

less revs sort of, more boost no. the more air/boost that goes in, the more fuel that also goes into the engine. the key to fuel economy isn't about rpm, it's about throttle position. the less throttle you use, the less fuel you will use. you can rev it out to 4000rpm at light throttle and use less fuel than someone flooring it and only reving to 3000rpm. using light throttle will keep the ecu on closed loop (using the o2 sensor to keep the AFR between 14:1 and 15:1). when you put your foot down a bit further the ecu goes to the standard mapping, so at the same rpm your AFR will drop down to below 12:1, plus the fact that there will be more air going in as well, which means more fuel as well.

[zoomzoom]

The question I have is whether the ECU is changing the A/F based upon the TPS reading or, RPM & airflow readings, or all of them. Probably due to the combination of the boost controller I use, and the weight of the car, even with light throttle I am usually seeing positive pressure on the boost gauge on acceleration. On the long uphill sections I travel on I am sitting on 5psi for minutes at a time. When accelerating I usually accelerate fairly quickly to a cruising speed and get the torque converter to lock up. Ive been experimenting with driving behaviours and fuel econ on this vehicle for years now and its the best fuel economy Ive ever attained (around 12.5-13L /100km round town). Like I said, YMMV.

[tripsteady]

will stop doing my stupid $hit , fill up as stated before and post actual figures to give a true indication of fuel economy. cheers guys

[joe2548]

WOW!!!!!!!

What a bunch of PLICS! LoL ... can't believe this guy thanked you. run till eeeemmmmpppptyyyy lol

You can> check trip meter> add 20L>check trip meter again to calculate fuel economy.(going off the guage line...) if the float tank in the changes every time then how can you guys know if your tanks empty? the needle drops below empty anyway... you are just saying hes not using the guage as a reference point and you are!? or everyone here is coughing and spluttering into the servo LoL...

just run till dry. (sarcasm.)

the bigger your tank is or the more fuel you put in the better your calculated avg fuel consumption will be. duh.

your stock gtst shouldnt be using more than 12L per 100km, first get new spark plugs(std gap is fine don't be picky). do the coilpacks(silicon fix works a treat) and run seperate power cable to ignition module-little black box), check afm. throttle position sensor, 02(yours is new) etc... hows exhaust smoke colour? excessive smoke? idle smooth?

you need some spanners and a multimeter... or a friend with some..

after that check(swap) ecu, injectors.... or just get it plugged into a dyno and have the stuff read for you...

BTW can someone please tell me how to check my fuel economy? tripsteady seems to understand how to calculate fuel economy, but I dont yet, please someone tell me...