25.5L/100km What The F*#!

[w8stedYouth]

I am have problems with my vt running at 25L/100km. I have recently installed a CIA from mace and Got some Aus made headers Installed.
I have not had an engine light come, But have been informed that if its the o2 sensors it might not register as a fault always.
I have cleaned my MAF sensor in the last 3 months twice infact. have changed spark plugs also 2-3months ago yet they always seem to be black and sooty(sorry about spelling).

Also the o2 sensors are they located @ the rear or the eng. w/ 2 wires going into the extractors I had installed???

Any help would be appreciated
CHEERS

[88GreenVN]

Yes the 02 sensors will be in the headers or extractors. Good bet they are buggered or the wires are not making good contact. Check the ECU temp sensor also - if the ECU thinks the engine is cold it pumps in heaps more fuel - like running on choke all the time.

[wana s' charge stock vt]

Yes the 02 sensors will be in the headers or extractors. Good bet they are buggered or the wires are not making good contact. Check the ECU temp sensor also - if the ECU thinks the engine is cold it pumps in heaps more fuel - like running on choke all the time.

would/could a similar thing happen with a cooler thermostat? run a bit cooler so use a little more fuel and run a bit richer causing black soot on rear bar? or would just a 10deg drop not cause the ecu it to adjust anything.

[88GreenVN]

The thermostat when not working correctly will get the engine overheating or if stuck open too cold - but the temp gauge should show this.

If the temp gauge is showing normal but the car is running rich it is most likely 2 things - o2 sensor or the ecu temp sensor. If over about 70,000kms the o2 sensors should be replaced if the car has a drinking problem.

[ahmedomnnea]

I have the exact same problem with my VX, 25L/100Km.
tried every thing possible, spark plugs, leads, oil filter, air filter, fuel filter, fuel pump, cleaned MAF, cleaned TB, checked O2 sensors (the voltage reading seems right), checked for vacum leaks (NONE), cleaned the injectors but no luck.
the weird thing though is when I disconnect the O2 sensors it doesn't come up with the "check engine" light and it runs the same even when disconnecting both O2 sensors, but though it comes up with the check engine light when disconnecting the MAF or MAP.
one more thing, should the numbers appearing in the dash (about the engine temp. and fuel consumption ... etc) be the same data provided to the ECU by the sensors? for example: when the dash reading is "engine temp. = 87C" that should mean that the ECU knows the engine temp. is 87C right? and when the ECU shows that the fuel consumption is 11L/h, should that be true? because my cars says "fuel consumption is 10.5 L/h" but actually it is 25L/100Km !!!

[88GreenVN]

I have the exact same problem with my VX, 25L/100Km.
tried every thing possible, spark plugs, leads, oil filter, air filter, fuel filter, fuel pump, cleaned MAF, cleaned TB, checked O2 sensors (the voltage reading seems right), checked for vacum leaks (NONE), cleaned the injectors but no luck.
the weird thing though is when I disconnect the O2 sensors it doesn't come up with the "check engine" light and it runs the same even when disconnecting both O2 sensors, but though it comes up with the check engine light when disconnecting the MAF or MAP.
one more thing, should the numbers appearing in the dash (about the engine temp. and fuel consumption ... etc) be the same data provided to the ECU by the sensors? for example: when the dash reading is "engine temp. = 87C" that should mean that the ECU knows the engine temp. is 87C right? and when the ECU shows that the fuel consumption is 11L/h, should that be true? because my cars says "fuel consumption is 10.5 L/h" but actually it is 25L/100Km !!!

Hi, The Temp gauge and ECU have different sensors so the gauge can report all is OK to the dash gauge and the ECU thinks the engine is stone cold. If the O2 sensors working correctly they should be a nice grey colour - if they are black they may not be working as they should be or the wires are not making good contact.

[w8stedYouth]

I have the exact same problem with my VX, 25L/100Km.
tried every thing possible, spark plugs, leads, oil filter, air filter, fuel filter, fuel pump, cleaned MAF, cleaned TB, checked O2 sensors (the voltage reading seems right), checked for vacum leaks (NONE), cleaned the injectors but no luck.
the weird thing though is when I disconnect the O2 sensors it doesn't come up with the "check engine" light and it runs the same even when disconnecting both O2 sensors, but though it comes up with the check engine light when disconnecting the MAF or MAP.
one more thing, should the numbers appearing in the dash (about the engine temp. and fuel consumption ... etc) be the same data provided to the ECU by the sensors? for example: when the dash reading is "engine temp. = 87C" that should mean that the ECU knows the engine temp. is 87C right? and when the ECU shows that the fuel consumption is 11L/h, should that be true? because my cars says "fuel consumption is 10.5 L/h" but actually it is 25L/100Km !!!

your dash shows 10.5L then I take it thats what its running at. If u have just started your car and its at 80c then it might run @ about 15.5-16L/100km but when shes at running temp cruising at 90km I would think she would be running at 11-14L/100km.
So I dont think our problem in that respect but if ur dash gets upto 25L/100 then yes we are alike but I dont like the sound of ur car idle/running the same with the o2 sensors disconnected, I will have to check mine now

[wana s' charge stock vt]

The thermostat when not working correctly will get the engine overheating or if stuck open too cold - but the temp gauge should show this.

If the temp gauge is showing normal but the car is running rich it is most likely 2 things - o2 sensor or the ecu temp sensor. If over about 70,000kms the o2 sensors should be replaced if the car has a drinking problem.

the thermostat works fine its just 10deg cooler. 82 instead of 92deg (its a l67). when moving it sits on 82/just above quarter but in traffic its basicly the same as the standard 92 deg thermo/just under half..
o2 sensor i reckon would be 120,000k mayb.. so might be the proplem after all..
cheers

[ahmedomnnea]

the dash shows an average of 10.5L/100Km, but in real life I fill up 60L and I only drove the car for 240 Kms, reset the trip when filling up and drive another 240Km and again 60L, been happening for me since I got the Jan 2009.

[pablo]

Some prick isn't milking your tank are they?...also, with the new exhaust fitted, your not giving it heaps all the time, just to see how good it's going. That'll chew the juice.

[88GreenVN]

the thermostat works fine its just 10deg cooler. 82 instead of 92deg (its a l67). when moving it sits on 82/just above quarter but in traffic its basicly the same as the standard 92 deg thermo/just under half..
o2 sensor i reckon would be 120,000k mayb.. so might be the proplem after all..
cheers

It could still be the ECU temp sensor tho - if this reports to the ECU that the car is stone cold it will run rich. The guage sensor and cooling system are all A1 you will not know anything is wrong from with in the car - bar the fuel bill. I guess at some point the car will need new sensors all over the place. The ECU temp sensor is a very important part of the fuel economy system.

[88GreenVN]

the dash shows an average of 10.5L/100Km, but in real life I fill up 60L and I only drove the car for 240 Kms, reset the trip when filling up and drive another 240Km and again 60L, been happening for me since I got the Jan 2009.

The cheapest thing to replace first is the ECU temp sensor. Over here they are $20 or so. The O2 sensors are around $70 each. if they are old - maybe time anyway. If your only getting 240kms - I'd get the sensors looked at.

If that fails you may have an manifold leak leaning out the exhaust gas before the o2 sensor and making the ECU go rich.

[graham7773]

I can't believe the specifications found on some sites for VT fuel consumption. I just Googled some specs for my car, a VT Acclaim wagon and in good condition I am supposed to be getting 7.2 litres per kilometre on the highway ! Does anyone get that sort of economy?

[drift-it]

the best i have gotten was on a 500km trip 8.2L/km which i thought was awesome as around town its 18-20!

[wamboin23]

vt onwards only have a single temp sensor that goes to the ecu, and then is communicated to the instrument cluster via the serial bus.

[Sean0]

I can't believe the specifications found on some sites for VT fuel consumption. I just Googled some specs for my car, a VT Acclaim wagon and in good condition I am supposed to be getting 7.2 litres per kilometre on the highway ! Does anyone get that sort of economy?

my 99 vt acclaim wagon with 65,500 ks on the clock just got 720 easy with motorway and into city and home , i thought this is good , tho i dont boot it , i just cruise

[w8stedYouth]

I drove the vt I made this post about from brisbane and drove it to darwin getting 800-850km out of the tank. cost me 780 in fuel and food

[88GreenVN]

vt onwards only have a single temp sensor that goes to the ecu, and then is communicated to the instrument cluster via the serial bus.

Opps - forgot about that - I was thinging the old ecotec

[mattyk]

has anyone considered a hole in the fuel tank or a line? maybe your loosing fuel whilst driving, if your routine is the same that would explain the consistent loss at one theory... but its just an idea that hasnt come up yet?

[Cúl-Báire]

has anyone considered a hole in the fuel tank or a line? maybe your loosing fuel whilst driving, if your routine is the same that would explain the consistent loss at one theory... but its just an idea that hasnt come up yet?

Could be on to something there Mattyk, fuel lines are high pressure so it would only take a tiny leak for it to piss everywhere, at driving speed you'd never know (as it's doubtful you'd smell it).