These cars have only 1 temp sensor, in the back of the head. If it is not working correctly it will show up on the temp guage- if its been running for 10 min & it says cold I would smell a rat! On the scan tool you should be able to read the O2 sensor, what readings are you getting? , should be between 0.1 to0.8v just remember this info is coming from the ecu so if its wrong 1 or more sensors are sending wrong info. Check your stf trims they should be around 0 (+or_ 5%) If your 02 reading is wrong (ie reading lean) the ecu will add fuel (positive fuel trim) to try & fix the 'problem" While looking at the fuel trims add another earth to the engine (1 jumper lead from batt (-)  to a engine earth) & see if the stft changes (it shouldn't)

Hi 4321

Much appreciated!  The O2 sensor generally reads 0.92ish at idle (regardless of temp etc).

Theorhetically, how long should it take for the car to reach op temp? I feel it seems a little long but it does get there and generally sits about 1/3 on the gauge.

Cheers

All else fails.

Trade the ute. $2500

Personal loan  $ 6000 ( $80 p/w)

                    _______

Buy Ba XR6T   $8500

ute or sedan.

 

Result.

-----------

$80 per week for loan

$80 per week for fuel.

Endless fun per week...

weeeeeeee   

44 minutes ago, Box stock T. said:

Buy Ba XR6T   $8500

ute or sedan.

 

Take 2 to 4 k from that and you've got a deal. 

You might need to take $2k off that trade price for a farked n/a too!

+1 for checking short term and long term fuel trims with a scan tool

0.9 at idle is rich, it should oscillate between 0.2 (lean ) & 0.8v. Like I said you have to work out if it's running rich or if the sensor is wrong. You've changed  it 3 times so I'd say that's not the problem. This is why reading your fuel trims is a usefull bit of info. 0% is the base program and it's +or - is how much the ecu is having to change the program to oscillate around 0.45v (which is stoichiometric 'perfect' mixture) it should go either side of this value trying to keep as close as it can to this reading at idle & cruise (it will go rich on acceleration, 0.8-0.9v) Next is to get your fuel pressure checked. stft are whats happening now & ltft are what it's modifying the program based on what it's seen over time

Thanks 4321, I'll check it out over the weekend! 

Why would running an earth from battery to engine change anything? Is there a known farthing issue with these cats?

Cheers again for the help!

Theorectly  it should make no difference but if there is a problem with earthing  (remember we are dealing with less than 1 volt) it can't hurt 

Any update to this, I've got a MKII 04 XR6T and have been dealing with the same issue, and similarly replaced alot of the same parts with no success. Just purchased Forscan OBD and from what I could see no significant faults that would cause this issue. Just purchased another o2 sensor in the hopes that the previous one I installed might have been d.o.a any help would be great! T.I.a.

Edited August 24, 20215 yr by stancez

Yes, I too would like to know what the solution, Can someone please let us know if Ascendancy254 solved the problem !