Yesterday at idle, -1 to -3 short term fuel trims, today -21.3 on both banks?

[CactusG8]

The car is now idling rich. You can smell it out the tail pipe. What could of gone wrong from one day to another to throw the car into a very rich condition at idle?

[ttz06vette]

Evap purge.

[CactusG8]

I have larger problems now. I got a dtc. but now hp tuners cannot find my vcm whether in scanning or editing mode. I tried a different usb cable. the cable is fine.

[CactusG8]

all very strange. after 5 minutes of driving I tried the scanner in a parking lot. it worked and brought up some U codes.
TCM disconnected from something. At any rate I was able to then use the editor to reflash and the codes are gone and the negative fuel trims are back at around -3. All too weird. While I was having the problems and I would start the car it almost sounded like the starter going out once or twice.

[CactusG8]

Sorry,, spoke too soon. I guess that was a separate problem which I seem to have fixed. I do not know how I fixed it. But for now that is fixed.

Now I am back to the minus 21.3s. I do smell a little fresh gasoline from the car. Why am I not throwing a code for this? I guess I will have to bring her in to see where the leak is.

[topher455]

You have to be careful calibrating the maf off of fuel trims after flashing the car with an e38 pcm. For whatever reason on various cars I have seen the ltft's act crazy after a flash. I usually do an update then drive the car for a while to let everything settle then reset ltft then calibrate the maf.

[ingsteve]

Did you reset ltft every time you flash? Try and calibrate always with ltft+stft at the beginning

[SultanHassanMasTuning]

are you o2 switching?

[realcanuk]

You have to be careful calibrating the maf off of fuel trims after flashing the car with an e38 pcm. For whatever reason on various cars I have seen the ltft's act crazy after a flash. I usually do an update then drive the car for a while to let everything settle then reset ltft then calibrate the maf.

This...

It seems every time I flash my tune, the trims are way off. After a few minutes I restart the logging and they are all good.