I think you may have the death flash, but I'm not too sure. If you do using a tuner will get rid of it

 

That sure looks like the death flash to me...... Timing is being absolutely stupid there...... probably at least partially responsible for the perceived lack of power. Bear in mind, your electronics are also new enough to incorporate 'torque management'..... which also tended to dial back power at high engine loads, to increase transmission life. (in a 6000 pound truck.... PCM doesn't know it is now in a 3000 pound Jeep.)

 

Generally you want as much advance timing as you can stand, without destructive detonation. I think the other guys are right, have a tuner provide their services.

 

Yeah, I'm gonna check a few other things, then pretty much go "in for a penny, in for a pound." If I'm gonna get a tuner anyway, might as well get a cam, intake, and throttle body at the same time and just tune it once.

I have to look a little more for something else though. I just can't believe that anyone at Chrysler would think that the driveability of this programming is acceptable. (If it is indeed JUST programming). 10mpg with no low end power on an engine that advertises 350 ft-lbs of torque... it can't even do a brake stand in gravel. Just sits there and bogs with your foot on the floor. If it didn't do that to me in low range when I'm wheeling, I'd probably just live with it, but I can't deal with my big loud V8 bogging out in low range when 2.5 liter 4 cylinders don't. Makes me feel like I wasted the whole winter doing the swap.

I'm gonna do the vacuum gauge test from the TSB to make sure I don't have a small plenum leak, gonna pull the valve covers and make sure all the rockers are lifting, and gonna do some of the same scan tool logging with my 5.2L Grand Cherokee and compare the curves and some of the other sensor numbers. Try to narrow this thing down a little and confirm if it really is just a programming issue.

 

Yeah, I agree, something is just not right there. You should be able to smoke the rear tires as long as you care to, and in that light vehicle, you should be able to do a LOT better than 10 mpg.

Have you tried driving it with the O2 sensors unplugged? (sets codes, but, forces the engine to run in open loop.)

 

I haven't tried that. I did a little digging with a friend today and we found I have the incorrect downstream o2 sensor. I can't imagine that that's the cause of all my troubles, but I ordered the correct one today.

As part of this swap, I had to get a few grand Cherokee parts to make it fit in my engine bay. (i.e. power steering pump) and while I was on RockAuto, I realized "hey, I need O2 sensors too!" And I ordered 1997 5.2L Jeep O2 sensors like a dub. I realized this about a month ago, but the parts store only had the upstream, so I changed that and it didn't change the driving characteristics, so I just forgot about the rear. The only obvious result on the scan tool was that it was not responding at idle, it was holding steady between 0.08 and 0.10v while the upstream was bouncing around as normal. While driving, the downstream O2 graph appears normal.

I like the idea of disconnecting the sensors and seeing how it runs.

 

That won't affect it at least it shouldn't. I drove thousands of miles on a bad downstream O2 sensor

 

I mean, it's possible I guess. Getting erroneous readings (that the PCM thinks are accurate) can be worse than no readings at all. Least I hope so.

 

Rear O2 just monitors the cat, and has very minimal affect on fueling.

 

I had an 04 Ram that somehow wouldn't accept the 02 sensor input, keep flagging it with an error code. I spent about $40 on a used one from eBay and fixed the problem. The first one they sent wouldn't run the truck, so they said keep it and we'll send you another. You could consider just swapping in another one and see what goes on. Could be that one of the inputs(bad or missing) is causing the reaction with the timing. I like to change one thing at a time, so I can monitor my progress and if the change is a negative result, I know what did it. Tossing in all the changes at once will complicate solving the problem.