Okay, so I have been running this Heep for about a month now. I have had all sorts of codes being thrown, all air-related. Usually the same ones. I have replaced:
both upstream O2 sensors
both downstream O2 sensors
ruined, oily AIRAID CAI (with completely stock system)
plugs (coil pack was okay, plugs were in horrible shape)
I get the P0171 and P0174 codes most of the time. I clear them off and they come right back. But the CEL occasionally goes off on its own for a few days. In such a case I check and clear the codes. After a day or two more the CEL comes back on with the same first code and frequently the same second code. Both indicate a lean condition, forcing the motor to run rich.
BUT I GET 17 TO 19 MPG ON THE HIGHWAY AND INTERSTATE!!!
So if I am running rich due to the computer I *should* be getting bad mpg numbers, but they are better than when I bought the thing.
I decided to check to see whether the dealership installed Bosch sensors as I have been told that these could confuse the computer.
I get to the dealership yesterday to pick up some parts I am installing this week. I inquire as the the brand of the four sensors they installed.
A lot of chit chat happens at the parts desk. Service Advisor (whom I trust a lot after none years of working with her) says that OEM would have been (most likely) NTK but that since these are no longer produced and DC seems to love Bosch right now that the replacements are most likely Bosch. They have had no complaints about them, but they do not replace all four on a 2003 jeep all that often, so I think the "no complaints" is just a lack of examples for this specific fix - maybe.
She said the parts guy told her that all of them come in Mopar-branded and that there is no way for them to tell who actually made the part. But he also suspected they were probably Bosch based on looking at them.
With a normal 17 mpg highway over five tanks of gas, could this simply be the computer and the sensor not liking one another, that my jeep is actually running just fine? Power and acceleration are fine (for 3.73s with 33x12.5s) and mileage is great (for a jeep).
I am assuming that the downstream ones really do not matter, brand-wise. I am also assuming that I need to purchase actual NTK-branded sensors online somewhere and install them myself, writing off the expense of the first ones as an "Idiot Fee" for paying someone to do easy work like this when I could have done it myself.
Sound about right?