2005 5.3 lm7 Major issues!

[Flyterpilot77]

I have a 2005 Tahoe z71 with a new/reman 5.3 lm7 that had zero miles on it 2 years ago and is out of warranty. So to start I would place my mechanic skill level at 7 out 10, 10 being a master mechanic, Basing that on how good i am at installing parts not diagnosing and I am very good at reading instructions. Which being in construction my entire life, i know instructions are just a guide.

The truck drives nearly perfect when cold/not at WOT As soon as it warms up here we go!
It wont shift into over drive SOMETIMES
its sluggish SOMETIMES
fuel trims are just fine
it shifts hard SOMETIMES
idle lightly fluctuates when at WOT (maybe 50rpm)
brake peddle sinks at red lights
about 10-15 fuse have lower than the rest resistance when multi meter is set to OHMS and black on black battery and red on the top of fuse with key off
fuel pressure at 50-52 while running and holds for a good hour or more after shut down.
when at WOT i can SOMETIMES hear a loud hiss only when i stomp it after already going at least 45 mostly obvious on highway trying to pass someone
I have a very bad sense of smell and taste but i can smell what seems to be benzene

What i have done and this is all with the cheap parts...
new fuel pump
injectors but could possibly be the wrong size, I seem to find a new size every time i look so i am totally freakin confused.
new plugs, wires and coils
checked all grounds and regrounded where needed.
new brake master C and new hydroboost
new water pump
new power steering pump
new alternator
new brake calipers, rotors and pads
now, something that might have an affect is i did attempt to put a new radio in, It was my first time since my very first truck which was an 87 chevy and so i just went in and cut wires without thinking of a harness and the new radio works but i have it wired direct to the ignition wire in the steering column because i couldnt get it to stay on , it would turn off as soon as i put it in gear wired- wire for wire.

As far as I know the odb2 most ODB2 readings are normal except
all injector circuits are faulted,
the cylinder balance rates are -500 except 2 or sometimes 4 will be -200 to -300 i do not understand how to exactly interpret that.
random codes once every 6 months mostly seeming to be from unplugging stuff while its running to check things.
it shuts off if i unplug the MAP sensor
shudders but regains when i unplug the MAF sensor
failed emissions test as well
acts like it has an intake leak but multiple smoke test and spray test i cannot locate it. It seems there more but thats all I can think of for now, anyone here that can possibly help please? Thank you!

It has what i call " short starting" also where you turn the key and it fires right up hard real fast only when at WOT also

 

[strutaeng]

Woah! That's a lot of information and stuff going on...

You need to focus on fixing things one at a time. My general rule when working on these older vehicles is: there could be more than one issue going on.

I almost NEVER unplug sensors because of what you are describing. Now you have more codes and don't know what's legit and what is a false code. Delete those codes and stop unplugging sensors. Injector circuit faulted: focus on that...

I'm sure someone will chime in and try to help

 

[Sam Harris]

Holy parts cannon Batman! As was stated, take this one at a time. And when replacing parts, I highly recommend OEM in nearly 100% of situations. Replacement of the fuel pump with a “cheap part” is going to cause problems and aggravation either shortly or immediately.

 

[Flyterpilot77]

Woah! That's a lot of information and stuff going on...

You need to focus on fixing things one at a time. My general rule when working on these older vehicles is: there could be more than one issue going on.

I almost NEVER unplug sensors because of what you are describing. Now you have more codes and don't know what's legit and what is a false code. Delete those codes and stop unplugging sensors. Injector circuit faulted: focus on that...

I'm sure someone will chime in and try to help

I truly believe its a ground issue I found, last night i have 17 fuses only reading about half the resistance of the others of the same voltage, I have removed the grounds and sanded the metal on the grounds behind the front left bumper, under the drivers seat chassis and the 2 in the back of the engine, one thing I did notice was the ground to front left of the block did not exist at all, there is a bolt hole as if it should be there and everything I read says it should be there. in the under hood box all in a row and all correspond to the issues. I literally LOL when I read your reply... Believe me I want to " Stop" lol! I just feel im on the brink every time so much my wife is sick of hearing "Ok this time, seriously, I got it" lol

 

[Flyterpilot77]

Holy parts cannon Batman! As was stated, take this one at a time. And when replacing parts, I highly recommend OEM in nearly 100% of situations. Replacement of the fuel pump with a “cheap part” is going to cause problems and aggravation either shortly or immediately.

I must be rich huh? lol! I am the point I will never sell this thing its teaching me so much except what I need to know lol!!

 

[GMfan72]

I must be rich huh? lol! I am the point I will never sell this thing its teaching me so much except what I need to know lol!!

I agree with you that it is probably a ground issue. I also agree with Sam H. to use OEM parts that are made to specs. Even though you cleaned up the contacts for the ground wires doesn't mean there isn't corrosion in the wire itself. And after 19+ years ..... plus I am not sure where you live but if they use salt in the winter months you will have corrosion in the wire itself. I would replace your main ground wire(s) with an OEM part. I have a 2004 Yukon XL that was having intermittent issues and after I replaced the main ground wire everything worked again. I also put an after market Radio in but I bought a harness for the radio from Crutchfield so all the control buttons on the steering wheel worked, alarm chimes worked and I added a rear camera. You may want to re-wire your radio using a wiring harness from Crutchfield to remove the Radio - direct wire to the ignition.