Originally Posted by Rubi4MyMrs
This sums up the latest of various discussions there have been on this thread. It seems like an idea that has no answer. If you can find someone to try it, let us know. We are all looking for solutions.
Originally Posted by badtux
My guess is you'll need to replace sensors too, to put in sensors that are compatible with the earlier ECM. Check one of the online MOPAR dealers and see whether the part number has changed between the 04 sensor and the 05 sensor for each sensor. I presume it's doable, with the caveat that you may need to do some soldering to change the ECM connector from the old to the new, and better be quite confident in your ability to read old and new wiring diagram for the engine harness
. That said, you're talking about big bucks there -- have you priced ECM's recently? It's a heckuva lot cheaper to just Fogmod your OPDA and keep an eye on it.
My Jeep had the OPDA problem before the original thread (Chrysler replacing cam...) was made. That is, I had to deal with this problem before it was well known. In fact my Jeep was even covered under a powertrain waranty but it was deemed electrical and not internal to the engine. Now I know better, but now it is also too late. I do have the recipet from the Jeep dealer (where I bought it used and the waranty was from) diagnosing the issue with the date/mileage.
This was around ~68k IIRC. I noticed the weep hole in the bottom and figured since I recently went wheelin it must have gotten wet/muddy inside. Again, I didn't know better. It was squeeling for about a week on and off, I'd hit the gas and it'd go away.
I bought a new one myself and installed it, this was when they were first around $120. I threw the old one out before I knew it could even be torn down and inspected. The shaft was binded pretty darn well and it took a lot of effort to turn.
When the FOGMOD came about, I then pulled my replacement OPDA which now had ~20k on it and did the mod. This is when they went up to ~$350. Now they are back down to $120 so I bought another, brand new one to keep as a spare. My cam gear is worn past the hardened stage, but so far all is well. Jeep has 96k on it now.
As for the electronics change. Thinking more into it, I don't think the distrubutor system is a good idea for a few reasons, I prefer coil pack anyway and the exhausts changed over. I'd like to find out if '01/'02 ECM/electronics differ from '03/'04.
I'm thinking that may be the best way. Yes, ECMs are expensive new - but that's why you go used from a wrecked Jeep. I don't care about changing sensors, wiring harness or splicing my own wiring. It is semi-common in the 80s BMW world to run an older engine on newer electronics for various improvements. It shouldn't be a whole lot different with the Jeep going backwards. Being a manual transmission and having minimal integrated with a body computer means it should be nice too.
I understand '05/'06 run JTEC, anyone have insight as to what '01-'04 runs? and are they the same or different as '03 was the TJ update, among things that changed - the oil pressure gauge went from "mostly real" to "idiot light", and in both cases, it was ran by the ECM.
If I could get the Jeep to run '04 electronics, including new early OPDA and change out my cam - then this stupid problem would be totally behind me.
At this point, even changing the entire wiring harness wouldn't be that big of a deal if it was required for the ECM. I don't think the 4.0 itself has many differences, but I do remember reading about the crankshaft position sensors being in different spots, flywheel vs crankshaft hub (front vs back of engine).
I have the '05 TJ FSM on CD, but the disc drive in my laptop (only computer) quit working. It'd be interesting to compare it to '03/'04.