johnnyrocket5150

Hello all!

This is my first thread and I'm hoping to get some feedback from anybody who might have a clue before I throw $300 at a new ECU.

The rundown:
1991 Cherokee, 4WD, 4.0L, Manual, A/C, 17k mi on the following....
New Parts: Motor (crate long block), distributor, coil, cap, rotor, wires, MAP/Crank/TPS sensors, clean fuel filter, rebuilt/cleaned injectors.... Alternator is good @ 14.58V.

Symptoms:
Check engine light comes on sometimes when it's cold outside and the engine runs like crap! Sputters/misses; "bucks" if I try to drive it (just like when the TPS goes bad); and pulls a DTC #41 (charging system malfunction) when I use the ignition self-diagnose method. Usually goes away when the motor warms up.

Questions:
Could this be the ECU going bad? (it was submerged in water at some point by yours truly)
If it is my ECU, can I check it with a multi-meter?
Could this be the result of a bad spark plug wire?

I will end up buying a new part as any junkyard part will likely have the same problems soon due to being the same age as the bad one in my Jeep. So any advice on good / bad name brands (and where to find them) to look for would be great! I am in Sacramento, CA and this is a daily driver... mostly stock.
Thanks in advance for any/all help!

93XJLI

the coolant temperature sensor causes a mess of problems with renix 4.0s, i'd replace that and go from there.

johnnyrocket5150

Okay, I didn't replace that. But the temp seems to be fine and consistent. Would the coolant temp sensor really throw up a DTC regarding the charging system? And make it run like crap? hmmmm well it's right near the back of the engine near the valve cover right? Maybe I'll replace it and report back if anything changes. Oh, and I meant that the thing acts up when the temp outside is cold.. not the motor.. my bad.

93XJLI

i honestly have no idea except that the sensor messes up the renix real bad when it goes.