VS 1995 using alot of petrol..

[-Guy-]

Hey,
I ran my tank dry and put 15 litres of Unleaded 91 from a BP.
Reset my odo..and I mananged 90km.

Does anyone know why its using so much? The car is stock..and I dont drive it hard or speed up to the speed limit fast.
Any help please?

[The1]

check for error codes first

Checking error codes VR/VS (Revised)

Most likely your oxygen sensors will be a culprit, only way to know if there working properly is to look at them while driving with a scantool or laptop. New Sensors do sell on ebay though for about $50 each there are two in the vs one either side of the engine in the exhaust pipes.

[-Guy-]

okay..
Thanks for ya help!

[hako]

You cannot really gauge your fuel consumption on 15 litres of fuel - you need to check it over at least a tankful and even then you must be 100% sure that you used the amount of fuel otherwise it really is just a wild guess.
However, my VS gets about 12L/100km in town driving but if it's heavy traffic and reversing etc it can go up to 17L/100km.(about 15L for 90km)
I replaced my factory oxygen sensors at 220,000km and only noticed a very slight improvement around town....a bit better on long trips although some people find a greater improvement.

[moff_man]

ive never replaced my o2 sensors in any of the cars ive owned and i still get what i call good economy 8.9L/100km on the high way and 12-13L/100km around town (no hills tho)

[The1]

ive never replaced my o2 sensors in any of the cars ive owned and i still get what i call good economy 8.9L/100km on the high way and 12-13L/100km around town (no hills tho)

Highway driving mostly doesn't use oxygen sensors as it goes into lean cruise mode over 70km/h, around town though id not be surprised if it dropped below 12 with new sensors, i sit at 10-11 for pure city driving.

[moff_man]

most of the time it sites on 10 but combine that with stop start etc i thought 12 13 was pretty good for the old donk, i also have a wagon with climate control etc so i have a bit of weight.

[The1]

yeh fair enough you got an extra 60kg's odd over a sedan. Mines a berlina sedan

[RX25SE]

Highway driving mostly doesn't use oxygen sensors as it goes into lean cruise mode over 70km/h, around town though id not be surprised if it dropped below 12 with new sensors, i sit at 10-11 for pure city driving.

I cant get near 12 around town. Im doing aroud 13. Higway is 8.9. Same as moffs VR.

Question:
Do VS go closed loop at idle?

I thought they did but mine wont according to the scan tool.

[The1]

Should be in closed loop, i have seen this problem on my brother in laws vs ute, he had the 4 wire oxygen sensors with heaters, once we grounded the heaters the problem went away, the ground loop issue would throw out the oxygen sensor "ready" signal thus throwing between open and closed loop all the time. It used to even do it while driving, id watch it on the laptop and when it wasn't in BLM mode it would throw it back out to open loop.

[Brett_jjj]

Should be in closed loop, i have seen this problem on my brother in laws vs ute, he had the 4 wire oxygen sensors with heaters, once we grounded the heaters the problem went away, the ground loop issue would throw out the oxygen sensor "ready" signal thus throwing between open and closed loop all the time. It used to even do it while driving, id watch it on the laptop and when it wasn't in BLM mode it would throw it back out to open loop.

Ive heard a bit about this problem before.My VS has the 4 wire heated oxygen sensors,but Ive never seen it do what you explained above,it just goes from open to closed loop once its been running for a few minutes.Does it only effect some VS's? Or all the VS 4 wire 02 sensors, would it be worthwhile earthing the 02 sensor heaters differently,just to be sure they are working properly?

[RX25SE]

I have fixed the earths and get a much better signal (LH was the offending side).
The sensors are genuine and only 9 months old. If I remember they were coming up as ready but still not showing closed loop??

[The1]

not sure what the issue is then sorry are you running stock memcal? as this can be changed via a flag. Otherwise i havn't see it before other than that one time, it's random with the earthing issue some cars don't have the issue and some do, alot i think were fixed by holden in the early stages of life when they went back for a service at the dealerships as it was a known issue to holden, though my brother inlaws Series 3 ute had the issue but the logs books indicate it never went back to holden after the first few services.

[Brett_jjj]

I dont have any trouble with them going to open or closed loop modes,but lately Ive had a few big differences in the readings when compared side to side,and they were genuine 02 sensors new from holden about 2 years ago.I thought it might be one of the sensors was starting to play up a bit,but now im not so sure.I might have to try this earthing thing and see what happens with the readings,I will post up what I find out.

[The1]

Ive heard a bit about this problem before.My VS has the 4 wire heated oxygen sensors,but Ive never seen it do what you explained above,it just goes from open to closed loop once its been running for a few minutes.Does it only effect some VS's? Or all the VS 4 wire 02 sensors, would it be worthwhile earthing the 02 sensor heaters differently,just to be sure they are working properly?

as long as your getting a good amount of crosscounts while BLM mode is ON that is when it's using the O2's otherwise it's not using them to update the learn tables and the Ready for each o2 sensor should stay on once lit after warmup.

[RX25SE]

not sure what the issue is then sorry are you running stock memcal? as this can be changed via a flag. Otherwise i havn't see it before other than that one time, it's random with the earthing issue some cars don't have the issue and some do, alot i think were fixed by holden in the early stages of life when they went back for a service at the dealerships as it was a known issue to holden, though my brother inlaws Series 3 ute had the issue but the logs books indicate it never went back to holden after the first few services.

As far as I know its stock memcal.

I was a Holden fleet car when new so I would assume it was serviced by Holden in its early life.

What do you mean by changing the memcal via a flag? I have not heard of this.

[The1]

flag simply means on off as a figure of speech.

[Brett_jjj]

My LTFT is showing up on the Tech 1 at 42% ,and the STFT is at 65%, and I got an error code 76 show up a while back on the tech 1,which said that the STFT short term fuel trim delta was high.I wonder could this be what caused it.It hasnt logged the error again,so I havent really given it any more thought until now.

[The1]

doesn't sound to good, it means it's compensating a hell of a lot from the o2 sensors, the sensors are saying that there isn't enough fuel so the LTFT adds 42% more fuel consistently. Usually the STFT will swing back and forth till it hits 0 which means it's reached 14.7:1 AFR which is the target ratio, my LTFT is usually around -13% for left and right banks.

[Brett_jjj]

Id say its the earthing thing.Or the sensors are stuffed.I will try the earth thing first.The car is still getting excellent fuel economy though,jeez it will be good if that is the case then,once fixed,it should be even better.Ive also noticed at idle, the air /fuel ratio is at 14.2 instead of 14.7..It always used to be at 14.7 unless the engine was cold.

[The1]

The tech1 has an o2 sensor test you can run that, make sure the engine is warmed up first and o2 sensors are "ready"

Is it 14.2 AFR at idle in closed or open loop, if it's open loop it will be just using the predetermined memcal values in the open loop table.

I never had the earthing issue with my car as mines a series 1 APR first off the factory line which has 2 wire o2's

[Brett_jjj]

14.2 in closed loop at idle.Ive seen this tech 1 test before and didnt even think of it.I will run it in the morning,I will let you know the result.

[RX25SE]

I had code 76 pop up a few times. Thats why I rewired the earths.

I have only checked it once since fixing the earths and no code.

I'll check it again now it has some more miles on it.

[The1]

14.2 in closed loop at idle.Ive seen this tech 1 test before and didnt even think of it.I will run it in the morning,I will let you know the result.

yeh 14.2 is correct at idle in closed loop