I did the plenum fix, keg. mod., water pump, timing chain, new sensors, magnaflow cat, and new 02 sensor. With just these things, will the pcm have a learning curve?

 

not really. assuming you had the battery disconnected for more than a couple of hours, then the pcm dropped its adaptive memory (big word) and reset itself to the default values.

so it should run fine right out of the gate, and it will fine tune itself over the next couple of hundred miles. i wouldn't expect any drastic changes, just maybe a little smoother idle, or a smidgen better mpg.

 

I had the negative battery disconnected for a solid week. I will keep up with the mileage and see what happens. Hopefully, I get better. I took a recent 6 hour trip, with interstate most all the way. Cruising around 65 to 70, I got 14 mpg. In fact, this is what I got taking two trips. With no stopping and running at that speed, I should be getting a little better. According to fuelmileage.gov, I should be getting around 16 to 17 hwy.

 

Government ratings are..... funny....... and do not take into account the MANY variables that influence fuel economy numbers.