Poor fuel economy - 6L manual

[exanVZ]

One other possible factor I can't remember if I mentioned already or not, but while car was at the smash repairer it had a whole new exhaust fitted under insurance, new headers, cats, cat back etc. full system. I vaguely remember reading something about coatings in a new exhaust or new headers can cause problems with o2 sensors, but not sure if that was just BS or if it's a real issue. Just thinking of reasons why it could be having these issues after having a rear ender repaired.

When used with an app like Torque it should be able to read the data to help with a diagnosis.

I would be checking short and long term fuel trims first. These will show if the ECU thinks its running lean and adding more fuel.

It should also be able to look at O2 sensor voltage to see if the ECU is seeing the correct info from them.

Thanks for the tips, I have that app so I'll look into it and see what I can find.

 

[Ginger Beer]

If they dropped or handled the O2 sensors like a monkey they may be the issue

If they are old, swap them out, there a cheap option when using a shotgun to search for faults

 

[07GTS]

the 02's if all is operating as they should are a self cleaning item, if they get dirty on the outside from poor fueling if it is corrected it will burn clean and thus it cleans the 02 sensor, same as your plugs a good plug is clean/tanish color for closed loop operation, the 02's should be a same clean color

 

[exanVZ]

Thanks for the input so far everyone. Will see if I can log some info through the torque app and have a look at that, not sure what I'm looking for exactly but a good opportunity to learn a bit more.

 

[07GTS]

if u startup cold the 02 data in mv will be high and slowly lower down and when it gets to about 45-55c coolant temp they should be hot enough to work accurately and then will enter closed loop, when in closed loop the mv reading will go from say 200mv to 800mv cycling up and down every second or so, if they are not cycling then may be getting lazy, if u can see the fuel trims LTFT and STFT if its positive number its adding fuel, if its negative number it removing fuel, just some general info

 

[hademall]

Just thinking of reasons why it could be having these issues after having a rear ender repaired.

Probably too left field, but could there be a possible leak from the fuel tank or a hose? Especially as it was a rear-end accident. Or was the tank replaced? I'm not sure you would always smell petrol from a vapour leak. I don't know, just saying.

 

[exanVZ]

Have had a look at what data I can pull out of torque, looks like I can get quite a bit. Not sure exactly how to read this but I can map fuel trim and rpm over time and looks like it's adding in a lot of fuel, but I'm not sure if this is normal or excessive. I can also log cat temps, afr, o2 voltages etc. which I have but hard to lay it all out on 1 graph.

 

[exanVZ]

Probably too left field, but could there be a possible leak from the fuel tank or a hose? Especially as it was a rear-end accident. Or was the tank replaced? I'm not sure you would always smell petrol from a vapour leak. I don't know, just saying.

fuel tank on the ute is basically right behind the seats so wasn't touched in the repair, don't think there's any leaks or anything but something i'll have to look into if I can't work out the issue.

 

[07GTS]

Have had a look at what data I can pull out of torque, looks like I can get quite a bit. Not sure exactly how to read this but I can map fuel trim and rpm over time and looks like it's adding in a lot of fuel, but I'm not sure if this is normal or excessive. I can also log cat temps, afr, o2 voltages etc. which I have but hard to lay it all out on 1 graph.

50% adding in at times ? looks like its overly compensating for something maby bad 02 sensors, if u can look at the 02's millivolts see what those are doing, but mostly a stock tune would be within 5-15% error pos/neg and a tuner should have it within 5% so if ur 50% have to find out whats causing it

 

[exanVZ]

I'm not great with excel but I managed to chart both fuel trim and o2 sensor voltage against the trip time to show what's going on with that, I have no idea how to interpret the output or if it even makes sense but maybe it will make sense to someone more knowledgeable. Thanks again for everyone's input on this so far.