Fuel Consumption - help

[firefox]

I have a r33 1994 model with a garett gt30 turbo and microtech mtx12 ecu and 4inch exhaust .

I am only getting 220 -250km on a full tank of petrol and this was the case before the turbo and computer upgrade.

It uses the same amount of fuel if I drive slow with barely any boost or trash it for the whole tank.

My mechanic say 'this is the best fuel economy you can get'.

Im pi##ed off with these figures and my mechanic so have 'finaly' decided to replace my O2 sensor (which i asked my mechanic about).

What I want to know is will the way he has tunned my ECU effect the way the new O2 sensor will work??

And all you other guys who say your lines get 400km + a tank, what kind of mods do you have?

Just help me please, give me so feedback please!

[Waldo]

i have high flowed turbo, hks front mount 14psi, 3.5 exhaust, tunned computer to run more fuel, boshc 040 fuel pump and i get aroun 450 - 490k's to my tank of premium

[r33_racer]

yeh im curious to get this too...i got 33 with avcr, powerfc, zorst, fmic std turbo running 13psi and a walbro pump and reg...and its running pretty bloudy rich and im getting about 250 if i thrash it...and about 300-350 if i granny shift it around...its putting out about 170rwkw...which aint much for the fuel economy im getting...ive heard of people with double my power and getting same economy.

[dangerous_daveo]

What size injectors? Because deadset that is horible. If your wasting that much fuel the car cant be tuned right, Id guess you would be infact loosing power, that or you have a MASSIVE ding in your tank, or your gauge is stuffed. Best way to work it out is fill the tank, then next time you fill it how many Ls you put in, to how many kms. That way its a bit more accurate.

[firefox]

What size injectors?  Because deadset that is horible.  If your wasting that much fuel the car cant be tuned right, Id guess you would be infact loosing power, that or you have a MASSIVE ding in your tank, or your gauge is stuffed.  Best way to work it out is fill the tank, then next time you fill it how many Ls you put in, to how many kms.  That way its a bit more accurate.

Yea ive measured fuel consumption that way, still about the same, and guage should be working ok, the fuel economy is just ****

using "standard" injectors

Should get a new O2 sensor fitted tomorrow, hope no PRAYING that fixes the problem.

[paulr33]

the dead 02 sensor will throw your fuel economy out the window. if its the stock o2 sensor, chance are it is a they never get changed then this is your likely culprit. if its still shithouse then find out if the ecu is closed or open loop, if its open then it might not care what the 02 sensor says and just run rich and waste fuel all the time

[RB30-POWER]

If you replace the O2 sensor just make sure the Microtech has closed loop turned on, or else it won't work obviously.

[hanyou]

where can u get these o2 sensors from and around how much? i only get liek 300kms from my tank too and im pretty stock

[R31Nismoid]

What size injectors?  .

What would injectors have to do with fuel economy?

[bangahh]

where can u get these o2 sensors from and around how much? i only get liek 300kms from my tank too and im pretty stock

oem nissan ones will set you back 150-200

somewhere on the forum ( use the search tool ) ford ef/ea not sure o2 sensor will fit however you have to modify the connector.

about 70-90

[dangerous_daveo]

What would injectors have to do with fuel economy?

One of my friends had problems with his being far far too big (previous owner of the car) and he had to run them at a way too high pressure so they sprayed the fuel correctly at lower RPM. Hence appaling fuel economy.

[Cubes]

microtech mtx12 ecu

'finaly' decided to replace my O2 sensor (which i asked my mechanic about).

Looks like you were taken for a ride.

The Microtech MTX12 does not use the O2 sensor. It is not Closed loop capable.

What will affect your fuel economy is light load ignition timing your afr's through light load. Theoretically you should be able to tune a non-o2 sensor car as good as an o2 sensor equiped.

Simply light load up to ~30rwkw and set afr's to 15-16:1.

If the tuner doesn't know what he is doing here you will get shiet fuel economy.

I still don't understand how to find the optimal light load ign. timing.

I'm unsure if you can do it via an EGT guage, possibly advance until the EGT drops to its lowest value then pull it back a degree, you then have the optimum advance for that rpm/load??? Possibly returning the best fuel economy as it 'should' be returning the best torque for that rom/load.

Advance too much and the motor will be working against its self resulting in less torque, too little and the flame front in the cylinder will be chasing the piston down the bore not actually pushing it the best it could if it were ignited slightly earlier.

I've got an RB20DET PowerFC on my R32 RB30DET, fiddling with light load picked me up from 430km's to 470-480 to a tank of petrol. ~50litres of fuel.

Its now returning fuel economy very similiar to the rb20det but with much more poke at low rpm.

[R31Nismoid]

One of my friends had problems with his being far far too big (previous owner of the car) and he had to run them at a way too high pressure so they sprayed the fuel correctly at lower RPM.  Hence appaling fuel economy.

If the injectors are properly installed with a decent ECU it shouldnt really matter at all.

Im using 740cc Nismo injectors and i get around 350km to a tank with the occasional squirt, and i think my tank is smaller than an R33 one

[firefox]

Thank for the help so far

I have changed my O2 sensor and so far i have gotten roughly about 200km from half the tank, but i think the last half of the tank runs out quicker.

However, most of the driving was 'freeway type' driving not really pushing the car a lot.

I'll see how the rest of the tank goes, but if its true what CUBES said that the microtech ltx12 doesn't support the O2 sensor then did i waste my money (cost $180 fitted by the way), and how come i seem to have better fuel economy?

Anyway i'll keep you guys posted.

thanks

[Cubes]

Thats impossible the O2 sensor has made any difference.

The Microtech ECU's DO NOT USE THEM, 100%, my old tuner Tim Possingham was the bloke who was in bed with Microtech and setup and tested the very first R32/R33 'Plugin' Microtech's.

They are NOT 02 closed loop capable, 100% of that.

The tuner 'may' have leaned the car out a little or done a little more dyno work + the freeway driving which does make a nice difference to fuel consumption.

[firefox]

Thats impossible the O2 sensor has made any difference.

 

The Microtech ECU's DO NOT USE THEM, 100%, my old tuner Tim Possingham was the bloke who was in bed with Microtech and setup and tested the very first R32/R33 'Plugin' Microtech's.

 

They are NOT 02 closed loop capable, 100% of that.

 

The tuner 'may' have leaned the car out a little or done a little more dyno work + the freeway driving which does make a nice difference to fuel consumption.

F*** i think you are right because my fuel level dropped down to like 1/4 left and i only got about 240km so far so i'm probabally looking at 300kn for the tank max.

What should i do????????????????????????????????????????

Take out the New O2 sensor and sell it, put the old one back in and get the ECU retunned?

Does anyone know how to get better fuel economy out of a Microtech LTX12????

PS. Forgot to say i have forged pistion, does this reduce fuel economy?

Basicly I just can't understand why my fuel economy is so bad and it pi**e* me of to have to pay $50-$60 for every 250 - 300km!!!!!!!!!!!!!!

Help?

[Cubes]

Damn.. I seriously would cry if I hit 3/4 with only 240km's.

I've just used 1/4 of a tank and clocked 117km's.

Fuel economy can be affected by a few things.

Tuning (AFR's and Ign. Timing)

Injectors.. What injectors are you using?

[Spook's_Skyline]

if i flog it, im not getting much more than 250ks to a tank

im still using standard ecu, but have custom plenum and throttlebody (big ones)

was only 350 a tank before the mods though

anyway to test if o2 sensor is a bit had it?

my fuel reading does exactly what yours is doign

hits about 200 half way and then nose dives in the last half of the tank

[firefox]

Damn.. I seriously would cry if I hit 3/4 with only 240km's.

I've just used 1/4 of a tank and clocked 117km's.

 

Fuel economy can be affected by a few things.

 

Tuning (AFR's and Ign. Timing)

Injectors.. What injectors are you using?

Using standard injectors. Running like 16psi, mechanic say "the injectors are close to being maxxed out"

Should i get them cleaned or something?

I think my next step it to try get a retune of my Microtech LTx-12?

ps. i also have a straight through Cat and used to get flames out the exhaust on gear changes under full throttle, now it has been tunned a little and black smoke comes out. And when i look at my car is see all this 'black exhaust dust' over the whole boot.

[r33GTS-t-200kw]

the 'soot' u are referring to is from the gutted cat more than likely, and it also tells you you are running very ruch aswell.. might be time for a better tune...