I highly recommend the Flagship 1 PCM for 2002-2004 3.7L Liberty KJs.
I have a 2003 3.7L Liberty Sport. The engine is a Chrysler workhorse found in several different Jeep and Chrysler vehicles (look it up on Wikipedia) over many years, IOW millions of vehicles, so it is mechanically reliable in and of itself otherwise it wouldn't have lasted in the marketplace. In order to get this engine to perform properly there is a combination of PCM, TCM ((powertrain and transmission control modules, aka "computers"), sensors (like the TPS, up/downstream O2s, etc), controllers (like the IACV, PCV, injectors, coils, etc), and fuses (in 2 different fuse boxes). IOW, there's a LOT of tightly interdependent electronic controls and electronic sensors integrated, and required to be functioning correctly, to make this engine work correctly. All of these things are electronic and operate using really tiny pulses of data at very high speed, meaning that your Liberty is 100% computer controlled. Also, all of the wiring for all of this needs to be well-insulated and properly grounded.
When I replaced the engine, I decided to replace the PCM at the same time. I called Flagship 1, gave them my VIN, received/installed a new (not refurbished) PCM.
I literally inspected, tested, replaced, every possible electronic component that affects the engine performance of a 2003 3.7L Jeep Liberty Sport. Everything. Cost me $1000s beyond the price of the Tristar block purchased from AutoZone (which works quite well as a reman replacement), and 100s of hours of troubleshooting and crawling around salvage yards. This protracted effort produced, for all intents and purposes, a mechanically brand new 2003 Jeep Liberty 3.7L Sport with zero miles on the engine.
During the renovation, there were many times that I hit a mental wall because the transmission suddenly started acting weird, or misfires started happening for no apparent reason, or WOT sounded like the Liberty was trying to eat itself at 100 MPH... and all I could think was, "It's gotta be the PCM". It never was. I even called FS1 a couple of times, even got an RMA code to replace it, but I would try "one more thing" before pulling the PCM and it always turned out to be an odd side-effect of some other electronic or mechanical component. The Flagship 1 was perfectly fine throughout and in retrospect, it was the one thing that I could always rule out as being a problem.
I have a 2003 3.7L Liberty Sport. The engine is a Chrysler workhorse found in several different Jeep and Chrysler vehicles (look it up on Wikipedia) over many years, IOW millions of vehicles, so it is mechanically reliable in and of itself otherwise it wouldn't have lasted in the marketplace. In order to get this engine to perform properly there is a combination of PCM, TCM ((powertrain and transmission control modules, aka "computers"), sensors (like the TPS, up/downstream O2s, etc), controllers (like the IACV, PCV, injectors, coils, etc), and fuses (in 2 different fuse boxes). IOW, there's a LOT of tightly interdependent electronic controls and electronic sensors integrated, and required to be functioning correctly, to make this engine work correctly. All of these things are electronic and operate using really tiny pulses of data at very high speed, meaning that your Liberty is 100% computer controlled. Also, all of the wiring for all of this needs to be well-insulated and properly grounded.
When I replaced the engine, I decided to replace the PCM at the same time. I called Flagship 1, gave them my VIN, received/installed a new (not refurbished) PCM.
I literally inspected, tested, replaced, every possible electronic component that affects the engine performance of a 2003 3.7L Jeep Liberty Sport. Everything. Cost me $1000s beyond the price of the Tristar block purchased from AutoZone (which works quite well as a reman replacement), and 100s of hours of troubleshooting and crawling around salvage yards. This protracted effort produced, for all intents and purposes, a mechanically brand new 2003 Jeep Liberty 3.7L Sport with zero miles on the engine.
During the renovation, there were many times that I hit a mental wall because the transmission suddenly started acting weird, or misfires started happening for no apparent reason, or WOT sounded like the Liberty was trying to eat itself at 100 MPH... and all I could think was, "It's gotta be the PCM". It never was. I even called FS1 a couple of times, even got an RMA code to replace it, but I would try "one more thing" before pulling the PCM and it always turned out to be an odd side-effect of some other electronic or mechanical component. The Flagship 1 was perfectly fine throughout and in retrospect, it was the one thing that I could always rule out as being a problem.
