rlcole321

who did the injector replacement?, if you, did you look at the back of the intake valve (or all of them) for cyl# 3 to see if it had excessive carbon build up on it?, how many eng revolutions to get up to 190 psi on compression test?, try pulling at least 3 plugs (I would do all of them) and doing a compression test on all 3 cylinders and see how many piston cycles it takes to get to full compression, if it takes a lot more to get cyl. #3 to come up then you could have a minor valve issue. I'm guessing you tried swapping coil and plug wires from another cyl. to see if that made a difference?

Yes!, Tuning is the BIG key to all this, it must be done right!, I did the same with my 18 'Rado, but I learned the tuning my self, and it runs great, good low end torque and pulls good to rev limiter 6500. So find a good tuner!

If you didn't know about the oil pump alignment tool, then DO NOT use the original oil pump, use a new GM oil pump, it comes with alignment installation assistance. Check youtube.

If you are sure the sound is not there when you disable the rear drive train, which sound like you do, then that really rules out the trans/TC, so it points to the Transfer Case, have you check the fluid in it for Debree?

Usually when the TC starts to fail you notice when driving at a steady cruise speed and the TC is in lock up, you will notice the RPM's fluxuates 50 to 200 RPMs, are you seeing that?

I did long tubes and built a full 3" single exhaust (along with a DOD delete cam kit) on my 18 'Rado and use my factory two cats and all 4 O2's, using an open flowmaster muffler and resonator, it sounds great and great power and low end torque. But you'll need to learn how to use a HPTuner system.

did you have good oil psi right after oil pump change?, if so, then could be variable oil pressure solenoid, (I think the 14's had them), or could be a problem with VLOM for the lifter control for the AFM system, that's at the end of the oiling system, I ran into that when I modified my VLOM after a DOD delete and VLOM modification, I forgot to plug the oiling port just below the oil pressure switch.

invest it a HPTuner and start trouble shooting, is there no fuel or no spark?

'No Pennies!", disconnect the battery overnight.

I have a 18 'Rado short bed 2WD, I've done a lot of mod's to it by choice , AFM delete, BTR Cam, Long Tubes, it's a great truck, but history does show some issues like you know, does it have the 6 sp or 8 sp trans?, my suggestion is invest in a HPTuner system and learn to use it (plenty of on-line teachings), it will be well worth it for dia and trouble shooting and even reprogramming

Wow, I didn't see O2B1S1, but if it is as high as O2B1S2 then you have a very rich condition (O2B2S1, S2 should be high, there downstream), and with the high negitive fuel trims, then there is something wrong, how long have you had the truck?, could the tank have been filled with E85?, what is the fuel rail PSI (high pressure)?

there has to be some sort of connection to the 12v battery, this might help some GM 5.3 Liter V8 L8B EcoTec3 Engine With eAssist Mild Hybrid System | GM Authority seems braking is what charges the 12v battery, conldn't find any schematics

Mikey, you should just bit the bullet and get a HPTuner set up, then you won't need to have any "Dongle" plugged in to the OBD port and you'll have SO MUCH more capabilities with the tuner!!, look into it!

these trucks have locker diff., so (usually) no additives are required, if it is only making the nosie on turns, then could be a locker issue. I have a 18 'Rado (with some performance work), and sometimes when I get on it, the locker sometimes "Get's Stuck", and I have to back up to release it. Try jacking up one of the rear wheels and in drive "Slowly" release the brake and see if will lock, or make that noise, just be carful.

first, are you sure it uses R134A and not R1234?, second, if the low side is reading 0 psi, then the compressor shouldn't be coming on, low side pressure switch should keep comp. off. Possibly your gauges low side connector is not pressing open the Shrader valve. Now with only 30 to maybe 40 degrees difference in incoming and outcoming air from the evaporator, at 115 degrees outside, you may be only getting 85 degree air coming thru the vents. with the AC on, is the low side line coming out of the evaporator feel cold or cool?, if so then there is some low side pressure.

how long have you had the veh.?

A lot to deal with, I think you'll just going to have to have you buddy with the HPTuner ride along with you and look at live data to try to find it, could be fuel or timing related, could be the knock sensor system going haywire, or the traction control going bonkers. Usually when get into that much mod's on your vehicle, you should get your own HPTuner system and learn how to use it, I did.

time to go back to "Old School", use a DVM to check power at the power wire going to the fuel pump, use DC first to see if it is a solid 12 vdc, then check on AC (unless you have a dwell setting on your DVM) , if PWM then it should read an AC voltage, if no PWM then it will read 0 v. Then you can go from there, may have a short to power on the FP wire.

first, "Why lower a 4WD truck??, Anyway, I have a 18 'Rado, lowered 4/7" and I did Long tubes and a custom built 2 into 1 3" exhaust w/fact cat's all the to the rear, still plenty of room over the axle.

may have an issue with the VLOM (valley lifter oil manifold), that's where the oil goes to control the AFM, also does this L83 have a vane type oil pump or gear type? (gear type requires alignment). Anyway, I did a AFM/DOD delete on my L83 and modified the VLOM by removing the oil solenoids and forgot to (actually didn't realize) plug the oil galley going to the oil solenoids which'd caused low oil pressure at temp., but after I plugged the port then oil press. was good. So check that for leaks or oil drainage.

What I notice as strange, is both downstream O2's are the same down to the 8th decimal point!!, got to be something going on there.

Yeah, I saw that too, about the Toe issue, I know when you install new parts like springs, they will "settle" in and drop a little bit and any change in camber (or caster) will effect the toe angle. I'm also old school for frt alignments, because of road crowns and right lane driving, you need 1/2 to 3/4 of a degree more caster on the right side (to keep from pulling right, if it pulls right, add caster to the right, if it pulls left, add caster to the left), also the more caster you have the better the vehicle will track straight. When you mod the suspension then you'll need to "Mod" the alignment spec's too!

If you monitor O2, B2S1, (upstream) and it's cross counting good and your long and short term fuel trim are reasonably in the center, and the B2S2 (downstream) O2 is stuck at .950 or higher, then the data doesn't fit, but if both O2's are high and LTFT and STFT for bank 2 stay in the "high negative" range, then possibly fuel delivery problem (rich). An exhaust leak could cause some of these issues, but you normally see it in the fuel trim data.

Try turning off the traction control and if it still does it, then check the exhaust, cat's, Flapper valve (behind the muffler, it's for controlling AFM/DOD "drone" and adds back pressure to exhaust). Since it's direct injected (injectors fire into the cylinder, not the intake), could be a fuel starvation problem (borderline Hi pressure fuel pump), as long as the air filter is good. Just a couple of ideas!

As for the "Tow" use, since you haven't own it from new, someone could have "Retuned" the ECM/TCM and changed things and now it is disabled. It's very easy to do that with HPTuner.