I can't answer your first question but maybe I can provide some insight to your second based on what I've learned and experienced. I'm fairly new to this tuning game so keep that in mind and maybe someone could correct me where I'm off-base. I'm an old school carburator based engine mechanic. You used to do all this stuff with a screw driver, a few instruments, and a good ear.
Most common answer I hear for those high LTFT readings is "Air Leaks". I would argue that this is only one of other possibilities. High LTFT results from the PCM thinking your air/fuel ratios are too lean: too much air or not enough fuel. The PCM relies on a number of sensor inputs in a "closed loop" system to make this decision. Therefore, if the PCM is getting bad data from those sensors, it's not going to make the correct adjustments to the trims. Additionally, any problem with the fuel delivery system or the ignition process could contribute to these PCM adjustments if all the sensors are working correctly.
Too much air is one possibility. Adding the CAI will certainly allow more air to enter the system. The MAF sensor tells the PCM how much air is entering. My LTFTs were pegged at +25 when I ran my first log. I tightened everything I read about and they were still high. Cleaned the MAF and they came down to about +20. Even though the sensor checked within limits, I replaced my MAF (stock) anyway and they dropped to about +11.
The system also uses the MAP sensor to monitor the manifold pressure. A bad sensor will give the PCM bad data. Vaacum leaks in the system would cause the sensor to tell the PCM that the MAF is lying and additional air is getting in so it adds more fuel to compensate. I plugged a vaacum gauge into my manifold and everything checked okay but I re-torqued the intake manifold anyway. I checked all other areas by spraying starter fluid in every possible area that leaks could occur. I didn't notice any increase in idle speed when I did this so that looked good. I've got new intake gaskets so I may replace them soon just for good measure.
The IAT sensor and TP sensor are also involved in this closed loop system. IAT tells the PCM how dense the air is. I might get this backwards but here I go: higher intake air temps will make the PCM think "less dense" so I need less fuel. When the engine is cold, the IAT should be close to the ambient air temp. After warm-up, the IAT will be higher than ambient temp. I have a temp guage in my rear view mirror and using the Predator was able to check this reading. The TPS tells the PCM whether it is at idle, part throttle, or WOT and the PCM adjusts accordingly. A bad TPS will fool the PCM as well.
Your O2 sensors (sensor 1 on both banks) tell the PCM how efficient the combustion was and whether or not the air/fuel ratios are where they need to be. Too much O2 after ignition is complete = not enough fuel so the PCM wants to add more. Air leaks near this sensor would lead the sensor to believe the combustion was inefficient and send bad information about the efficiency of the ignition. In the end, the O2 sensor has the final say with things. If they're bad, then they're lying to the PCM about the true situation. Mine were all brand new when I started so that wasn't a concern but I did tighten them up. I had also replaced my exhaust so I had new exhaust gaskets but I checked they were installed correctly and retightend the exhaust at the manifold.
Besides bad sensors or air leaks, a problem in the fuel delivery system could potentially lead to incorrect PCM adjustments. The fuel pump, fuel pressure relief valve, injectors, and fuel leaks are other possibilities. Low fuel pressure can cause inadequate fuel delivery. I checked the pressure and relief valve and they checked out to be within limits and functioned properly. If injectors are plugged or not functioning properly, they won't be delivering the right amount that's commanded by the PCM leading to the O2 sensor telling it to add more fuel. I checked the injector balance and that also checked out within limits.
Looking at your LTFTs for both banks, you might have something going on with bank 1. This one is significantly higher than the other. I'd say air leaks, injectors, or bank 1/sensor 1 on that side need a look. Also, the difference could be incomplete combustion on bank 2 leading to a lower LTFT on that side so check the spark plugs, coils, and wires there. My bank 2 tends to be slightly higher than the other (+.78 to +1.56) so I think that's close enough to get my LTFTs dialed in at -2 to 0 with the Predator. In your case, there's too much of a difference to get dialed into this range.
I have yet to do any adjustments other than shift related adjustments until I get my problems resolved. It looks like the MAF, even though it checked out, was my problem. Or, at least one of them if there's others. I'm still looking and putting on the miles to let things settle in before running another log. I'm lucky to have all the toys to do this work myself. If you don't have a scanner with bi-directional controls to check the systems I've discussed, you'll need a mechanic to check things out. Doing all this gives me a reason to hang out in the shop. My wife thinks differently.
Thanks for reading
and I hope this helps. Anyone out there that wants to shoot holes in all these theories, have at it. I look forward to being set straight.
Bob
