So i took my 96 xj6 to the jag dealer and paid a wopping $382 to get an engine setup done to orientate all 4 o2 sensors and the new tps i installed. When i went to pick the car up they informed me that the o2 sensor in bank D was not working and that the engine set up could not be completed as a result. However after i picked the car up the gas mileage significantly improved. My question is if this would erase from the computer when i disconnect the battery? I recently took down the speedometer to change the back lighting to blue and had to disconnect the battery in the process and now it seems that i am getting very poor gas mileage again. Does the setup need to be done again? should i replace the o2 sensor myself and then take it back and demand they do the setup again for free? (I wish!lol)

 

Many folks are like I used to be -and that is in denial about the need or value if the tps calibration or the O2 orientation. I just could not believe any manufacturer would design a car with that complication. As you have learned, that combinatio of procedures can do something to dramatically improve gas mileage.

As to your question, I am certain that the orientation and TPS calibration survive power down. So, the only caveat is do not mess with the TPS to throttle mechanical alignment, and get your O2 sensors connected to the same plugs and you shiould not need another orientastion.

Good luck.

 

Would you mind explaining what tps stands for?

EZDriver

 

Thanks Spark! Always a great help! and EZ, TPS stands for Throttle Position Sensor. IT is located under the throttle body and tells the computer the position of the throttle blade as it relates to the gas pedal and the mechanical throttle blade positioning screw as well. Others will chime in im sure.

 

The closed throttle adaption, idle speed control valve (ISCV) reference position, exhaust gas recirculation EGR valve reference position and long term fuel trims (LTFTs) are all stored in non-volatile RAM inside the engine ECU and so are maintined even if the battery is diconnected.

Having said that, I have once experienced an apparent loss of closed throttle adaption following a winter lay up of several months with the battery disconnected. The throttle was not disturbed in any way during this lay up so I can't offer any other explanation for the loss of closed loop idle speed control. 5mins spent with an Autologic service diagnostic tool soon had the closed throttle adaption reset, and the engine would enter closed loop fuelling as normal.