Fuel Consumpton HELP PLEASE!

[fonzo]

Ok, 2 new oxy sensors, coolant temp sensor. ive replaced the oxy sensors i went for a 100kmh drive with cruise control on over a 15km distance and it used 3 litres of fuel. i went to pick my mrs up from tafe. a 2 mintuire drive start stop. 2 litres of fuel....its not leaking. i got up it and it has some real pull about between 80 and 110kmh. i havent done the oxy sensor earth thing yet, new plugs, new leads, new coils. HELP someone please and please explain in simple terms im handy with my hand buy get easly confused when it comes to wiring . thanks

[Brett_jjj]

Maybe dragging brakes,does it roll along or downhill easily?You can jack it up and spin each wheel to find a dragging brake.

[fonzo]

nah it rolls

[moff_man]

may i ask how are you mesuring the 3L of fuel used?
also how black is your exhaust tip, the blacker the worse it is.

my gauge on my vr was foulty at one stage and i thought i was using way too much fuel, but in the end it was just missleading.....

edit you have a berlina.... whats the inst fuel displaying at 100km/h?

[fonzo]

p.s i live behind a servo. drove around trip computer said it had used 8 litres of fuel..took 8.2 litres of fuel. so its pretty close to spot on

[88GreenVN]

Put the trip computer into diag mode and see how much fuel it's usiing per hour (start the car with reset pressed) You will have 3 modes to scroll through. The first in the middle screen will tell you what fuel is being used in Litres per hour. It should be around 1.5 to 2.0. L/Hour.

[88GreenVN]

Also were the old o2 sensors black/sooty or grey?

[fonzo]

ill run out and check how many litres an hour. the drivers side was caked in black shit left come out grey, exasust is black as hell

[moff_man]

could be anumber of things,

blocked cat, dud injector, dud airflow meter, blocked air cleaner, slipping auto, lots of things can cause high fuel consumption.

8.2L of fuel for a drive around the block is verry high, i drive to work which is 10km and use less than 2L approx

the engine is running smooth, that should be a no brainer for fuel consumption!

[88GreenVN]

ill run out and check how many litres an hour. the drivers side was caked in black shit left come out grey, exasust is black as hell

The right side was not working and will be the problem for sure - re check the earth on that side - clean up the contacts in the connector too.

[fonzo]

okay i dunno where this litre per hour thing is i got a vs2 berlina i got fuel 1 . underload highest was 50.3 crusing it bounces between 5-6 then press mode again and i get fuel 2 now thats between 4.9 and 5.2 but erratic as hell! "fuel one" will stop on a number at 60kmh fuel 2 doesnt stop moving

[88GreenVN]

This may help - the Holden book sheet is in this thread - Post 16.

VS L3 dash speed alert/digital speedo - 4 BUTTONS?

[fonzo]

arhh sorry guys theese are 2 BRAND new oxy sensors the old right hand side one was black and the left was grey. it was bad fuel economy before now its worse wit hthe new sensors ive checked all the plugs its all plugged in. i dunno what the hell is going on!!

[88GreenVN]

The second reading is the voltage from the fuel gauge sender unit.

4.4 = Full tank
6.6 = Half tank
8.5 = Empty

[88GreenVN]

okay i dunno where this litre per hour thing is i got a vs2 berlina i got fuel 1 . underload highest was 50.3 crusing it bounces between 5-6 then press mode again and i get fuel 2 now thats between 4.9 and 5.2 but erratic as hell! "fuel one" will stop on a number at 60kmh fuel 2 doesnt stop moving

At idle the reading should be nice and low - around 1.5 to 2.0.

If higher that that the fuel going into the motor may well be to high - meaning the sensors are reporting back to the ECU the engine is lean.

Re check the earths on the RHS. Also you did the ECU temp sensor - not the gauge sensor?

[fonzo]

okay i started it up. 1.5 for about half a second then right up to 4.0 then down to about 3.4 then 3.0 then moved between 2.8 and 3.2 moving slowly at all times not erracticly.

[fonzo]

yeh its the coolant temp sensor i got that bolts in just under the thermostat.

[88GreenVN]

okay i started it up. 1.5 for about half a second then right up to 4.0 then down to about 3.4 then 3.0 then moved between 2.8 and 3.2 moving slowly at all times not erracticly.

Hmm - the page says it should be between 1 and 5. so your car at idle sounds like it's OK.

I'll test my V8 in the morning and see if it's stable - last time I checked it was at 1.5 - but that was a long time ago. I'll report back tomorrow.

[88GreenVN]

arhh sorry guys theese are 2 BRAND new oxy sensors the old right hand side one was black and the left was grey. it was bad fuel economy before now its worse wit hthe new sensors ive checked all the plugs its all plugged in. i dunno what the hell is going on!!

If the temp sensor is new and working as it should (left o2 sensor says the old one was) then the problem is the right hand side.

Is the connector on the temp sensor making good contact and is the left o2 sensor still grey.

[fonzo]

yeh i dont understand why its got worse after i have new sensors. i took the plenum cover off and cleaned all the carbon and everything out. its really annoying

[fonzo]

oh and sometimes it gets really shaky idle and misses a bit at very low speed like coming off the thottle to turn into a corner then u get back on and its missing a a bit. does it lots with the air con on. and taking off from the lights u can see the computer trys to correct it. it almost stalls sometimes

[88GreenVN]

oh and sometimes it gets really shaky idle and misses a bit at very low speed like coming off the thottle to turn into a corner then u get back on and its missing a a bit. does it lots with the air con on. and taking off from the lights u can see the computer trys to correct it. it almost stalls sometimes

Hmm the bummer is that until what ever is playing up goes and dies the issue hides like a rat.

Could be coils/DFI or CAS on the bad idle. Hard to say. The TPS could be also in need of being re set.

Check all the vacuum lines for splits or cracks - could be sucking in air some place.

[fonzo]

sorry hahaha forgot to add it shit a coil last week. has 3 new genuine coils too LOL

[Paiste402]

try and get hold of a mate with the same car and swap ECU's to see if it still does it. a bum ecu will give out shit performance no matter the signals coming in. Its just a thought since uve done everything else just about and a handy swap between mates saves u money until u actually need another one

[admir87]

mate, the fact that the right oxy was black shows something...most likely earth problem, u mite have to cut the pink wire, or, fix it the proper way

also pull ur plugs out on the right side, as if the oxy was black, they'll be black too