Ok, folks, long time Mopar enthusiast, (first car was a '67 GTX, back when they were not collectable) first time on this forum.

Have a 2004 Sebring Sedan, 2.7 V-6, auto trans, which I drove into my shop. Had a light bearing rap, but no driveability problems, so I bought a used engine from a reputable local recycler, also out of an '04 Sebring with 49,000 miles. The door jamb sticker on my car has a production date of "1-03" but it is an '04.
Upon getting the engine home, saw that it appears to be the "new engine controller" version from later in the production year, so I swapped the following items from the original engine onto my replacement engine:
cam sensor, throttle body with original TPS and IAC, all four oxygen sensors, flywheel, oil pressure sensor and used the original engine's wiring harness and engine controller. Made a jumper to mate the new engine's knock sensor to the original wiring harness, thereby not chopping the original harness or the pigtail of the new knock sensor. Also bought a new crank sensor and put that in the transaxle housing. The replacement motor still has the newer coils, injectors, fuel rail and intake manifold. I did put new spark plugs into it before installing the motor.
I am a fanatic when doing repair work and have put every clip, wiring harness, harness route, position assurance tab, etc, back in place. Everything is installed properly from a physical standpoint, and I checked the wiring and the pins on the connectors again. Nothing out of sorts.

Upon installing the motor, I find the engine will not start. I verified spark at one cylinder, and also checked that cylinder's compression, which was 179 psi.

Upon reading another thread on the forum, I see that pulling the plug on the cam sensor may get it to fire, so I tried that. The engine did fire after 2-3 seconds of cranking, and it smells like it might be running rich. It does now throw a cam sensor code when the sensor is unplugged. I plugged the sensor back in, and it will not start.

Anyone have any thoughts on what to try next? Am I destined to have to open the motor up and replace the cam gear that the sensor picks its signal up from, or is there something else to try?
Thanks for reading my post.

 

Yeah...But you aint gonna like it......

The difference between the two, is the "FLYWHEEL".....

Theres no way around it, the motor is coming back out....

 

Thanks for the reply. I do have the original flywheel installed on the replacement motor. This is the flywheel from the "First Gen" set up. Do you know if the cam gear is different between the fisrt and second gen controllers? The cam sensors are physically different, although the harness plug is identical on both. In my case, it seems like the issue is related to the cam sensor. If it is plugged in and talking to the ECM, the engine won't start. If I unlpug it, the engine starts and runs.(I assume the ECM susbstitutes a baseline value in the absence of a signal from the sensor.) If I plug the harness connector back on the cam sensor, the engine reverts to the "no start" condition.

 

cam tone wheel is wrong remove the front cover and look at the slots on the old engines cam and one U have in there

 

Yes, I figured I was heading in that direction. Do you hear the theme from Mission: Impossible in the background? I'm going to see if I can slip the cam gear off to swap out the rings without taking off anything more than the valve cover on that side of the head, but as I recall I don't think there is enough clearnace to do that with respect to the outer casting on the head. I know, fat chance, I'll be pulling off everything and doing a whole timing chain re-do.
I'll open up the valve cover today and match up the tone rings between motors, and post my findings later. Thanks for your insight Chrysler Tech.

 

Eureka!! Took intake and front valve cover off, then sized up what I had in front of me. The replacement (next gen) cam tone ring was riveted on, while the old motor had its ring secured by two small bolts. Had to stuff rags everywhere, and cover the entire engine up. Locked down both cams with vise grips, as well as both sides of the cam gear/timing chain. Put paint marks on everything, then ground the rivets off the tone ring. Took the two main bolts off, holding my breath that the motor didn't move. Slipped the next gen tone ring off, put the old motor tone ring on and bolted all four bolts (two main, two small).
Put everything back together, praying for a pre-Easter miracle. Turned the key...and it fired right up, with the cam sensor plugged in, of course. Shut it off, cleared the codes, started it back up and it did not throw any codes! Wow. Its finally running.

 

78....

My sincere apologies..... For some unknown reason, I had 3.5 stuck in the brain....

Obviously I was wrong, but then again, you figured that out on your own..

Glad it worked out.

 

So just to sum up the differences for closing this thread, here's what I had to do to use a "next gen" engine, VIN code "R" replacing a "first gen" VIN code "R" engine in a 2004 Sebring:

Physically, engines are the same (as far as bolting everything back together, at least), except for the securing of the knock sensor.They are different.
I had to change (meaning swapping first gen parts onto the replacement next gen engine):
>engine wiring harness
>flywheel with tone ring
>cam sensor and cam tone ring
>map sensor on intake manifold
>oxygen sensors (all four)
>throttle body with IAC and TPS from old motor onto new intake
>had to make a jumper to connect the old wiring harness to the newer knock sensor
>had to drill out one molded shut vacuum line in front portion of intake manifold
>engine controller
I kept the following parts from the next gen engine in place:
>fuel rail and injectors
>ignition coils
>exhaust manifolds (as above, I did have to swap injectors)

Hope that helps future installers. If I have missed any sensors or anything else is not clear in my summary, please reply. You will have to open the motor up to change the cam tone rings. You have to look VERY closely to see they are different.

 

Whoops, I see I said "injectors" when I meant oxygen sensors in my summary where I talk about keeping the new exhaust maifolds in place. Sorry.

 

Good work, and good report.