2007 Jeep GC WK 5.7L High Total Fuel Trim at Idle/Rough Idle/Stalling/No Codes

2007 Jeep GC WK 5.7L Hemi
Sx: Irregular Idle, occasional stalls at red lights, No codes.
Data:
1. Fuel Trims at idle: ST: +/- 2 LT: +12-14% As idle increases the total fuel trim drops to 8-9. Suggests a lean condition due to vacuum leak or fuel delivery problem.
2. Vacuum at idle: 22 in hg.
3. Brake booster holds vacuum, Brake booster check valve holds vacuum.
4. Plugging evaporative purge port on intake manifold has no effect on vacuum or fuel trims.
5. Smoke Test shows no leaks. Propane test shows no leaks,
6. O2 sensors responding normally.
7. Adding propane to intake instantly drops fuel trim.
8. Fuel Pressure at the rail: 60 psi; Injector pulse times on all 8 injectors are about equal on scan tool. All injectors effect the idle when shut off.
9. EGR error=0 Gradually increasing EGR opening with scan tool eventually stalls the engine. If the EGR was leaking, it should produce a rich condition on a MAP engine, not a lean one.
10. No misfires
11. COP induction waveforms are all looking the same, as are the injector wave forms.
12. PCV valve is clean. Hose was hard but not leaking.
Work done:
1. As I found no source of vacuum leak I focused on the fuel delivery. Pressure at the rail being 60 psi I went for the injectors. I performed a fuel injection service at fuel rail with 32 oz (16oz x 2) of Berryman B12 chemtool at 30 psi using OTC 7649A.
2. Replaced PCV hose.
Results:
1. Idle is smooth.
2. No stalling at red lights.
3. LT fuel trim at cruising speeds (60-70mph) is 0; STFT at cruising speeds +/-3.
4. LTFT at idle is still 12-14, STFT +/-2
The vehicle is driving better. It is much quicker at acceleration. It idles much better. Any suggestions on the elevated LTFT at idle?
Best regards,
Jake

I would disconnect/reconnect battery to reset LTFT so you can check if it definitely still has a lean condition.

I did that. I forgot to list it.

This morning I sat with the Jeep for about 45 minutes waiting for my wife. I had the live data going on my fuel trims. I used my Autel MS906BT and then took pictures with Blue Driver on my phone. Initially everything looked normal. The upstream sensors were fluctuating normally between 0.1 and 0.9. Then I noticed that if I would rev the engine to 3000 rpm and let it go back to idle both front O2 sensors got slow and wide. The idle faltered and recovered.

www.pbase.com/scottbergerphoto/jeep_gc_wk_57l_o2_sensors

I would appreciate some feedback. They are both dropping out at the same time that the idle falters.

Had a look at your O2 capture. That kind of slow response after an engine rev or sudden load change isn't unusual, IMO. The fuel trims always end up chasing the O2's around for a bit, which makes the O2's look slow.

The idle faltering can be caused by a dirty throttle body. Maybe you've inspected for this already? Definitely give it a good cleaning if not.

I happened to do a radiator in an '05 WK with a 5.7L last week, and got some known good captures off it. This one's long term trims were always negative, around -5%.

www.scanshare.io/share/1GuiGrXoAEerngYWf...14,17,19,50,51,52,53

www.scanshare.io/share/Xr4ICCnUWkCKxICFCpqdWg

I think it'd be useful to compare MAP voltage and throttle position, with a hot idle and no loads.

The last capture titled "O2 sensors at idle" logged at 16:43, the engine was just idling on it's own. No revs before. I took the TB off the engine and cleaned it about two months ago.