Trying to understand my Xcal2 data log - not sure what the ideal values should be on the fuel trims. I'm having an on-going issue with my O2's not working properly on Ban2 (mostly upstream sensor). Has been switching slowly, tending toward rich. Lately threw a code P2198 = Ban2S1, stuck on rich. Datalogged showed the O2 as almost non-responsive (I've replaced originals, same thing with new sensors, put old ones back in, same thing. Loaded my stock program, same thing) I conclude its not the O2 but something else.

I checked all over the engine with a propane wand, not apparent leaks with intake. Back pressured the exhaust, no leaks there either. So something is making it run rich on the driver's side.

So what am I looking for in the fuel trim values, and are there any other PID's that I can record that would help me narrow down why just one side is running rich - injector codes for example?

 

To answer you're question, the ideal fuel trim for short term is 0 to set a code normally the long term trims have to be greater than 12% this will set a code. the first ting that I would do while logging front O2 voltage is unplug each O2 sensor and see what effect there is on the data log, if there is no change in voltage when disconnected I would be looking at the wiring harness closely for a place where it has been damaged, using a digital voltage gauge you can test the voltage at the sensor itself to see if it agrees with what the computer is seeing, one side will be a red wire with a blue tracer and the other is Gray with Lt blue, depending on application these connect to the computer at terminal 87 and terminal 60 check the voltages there also. There is a connector at the passenger side on the firewall near the valve cover, same color wires. If the voltages are what you are reading then I would look at and compare injector pulse-withs, could be a bad injector an internal engine problem or an actual computer problem, You will have to test a lot more information at this point. If you like send me you're data log and I will see if I can detect anything.

 

Here is some additional information that may help you. http://www.motorcraftservice.com/vdi...tsid=diagsheet

 

I have a recent datalog that has fuel trims, spark, O2 voltage and a few other PIDs. Can you PM me your email address so I can send an excel spreadsheet?