2003 Liberty 3.7L sport, Reman engine from Tri-Star, p0304 code

[dtennes]

What battery are you running? A

 

[dtennes]

Its a 2023 Autozone $99 "Economy" piece of junk that the original gargage put in, after my brand new top-of-the-line $250 Goodyear mysteriously disappeared while in their possession... 625 cranking amps. Why do you ask?

 

[Johnny O]

Its a 2023 Autozone $99 "Economy" piece of junk that the original gargage put in, after my brand new top-of-the-line $250 Goodyear mysteriously disappeared while in their possession... 625 cranking amps. Why do you ask?

Libertys hate dirty power. Notorious for gremlins.

 

[dtennes]

Went out to Autozone and had the battery checked. Their scanner only came back with "OK"s... no metered readings, which is about as useless as it gets for troubleshooting.

 

[dtennes]

@Johnny O ...What year is your Liberty? If it's a 2003, do you have a capacitor spliced into the 14awg common for the coils?

 

[Johnny O]

@Johnny O ...What year is your Liberty? If it's a 2003, do you have a capacitor spliced into the 14awg common for the coils?

Mine was an 07 transition model. so half 06 and half 08. Dirty Power issues well known and documented all over the forums here across all the KJs and KKs.
As others have mentioned in addition to voltage, the numerous ground straps contribute to the sensitivity issues in the brain box.

In the case of the OP concerning the engine swap gremlins, it will make troubleshooting easier once a known good battery is installed and all ground straps are verified.
Next step is to examine all wire harness and connectors related to the code.

Only way to defeat gremlins is to take away the routes they travel.

 

[dtennes]

SUCCESS

A lot of false leads, but I finally got all of the installation issues resolved. I have posted a simple engine replacement checklist here:

https://www.jeepkj.com/threads/engine-replacement-checklist-kj-2002-2003-and-maybe-2004.80359/