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Blancotahoe

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Needing Help!
I have a 2007 Chevy Tahoe LT 5.3L V8
Ive owned it for 2 years after about a month of owning had a Cyl. 7 missfire, new plugs / wires, no fix, went down the entire rabbit hole and found a stuck valve, now i sit here today, absolutely stuck, still having a missfire (cyl 1 & 6), EVAP codes, And throwing a “No Communication” on every Control Module (ECM, TCM, BCM) everything i have done below
——————————————————————
• New Plugs & Wires
• New Injectors
• New Coil Packs
• New Cyl. Heads (Reconditioned)
• New Lifters
• New Lifter Guides
• New Push Rods
• New Throttle Body
• New K&N Intake
• New Catalytic Converter
• New O2 Sensors
• New Terminals
• New Fuses & Relays
• Replaced Entire Engine Wire Harness
• New Cam & Crank sensor
• New MAF Sensor
• New Intake Manifold Gasket
• Cleaned,Replaced,and Added Ground Wires
___________________________________
A few pointers to help that i have found out,
• All mentioned items have been tested
• I own an Matco Scanner, Multi-meter, etc to run tests
• When putting Scanner into OBDII port dash goes wild, and truck drops RPMs and Bogs/ almost dies
• Truck will sometimes retract Check Engine Light when driving
• Not getting power to Fuel Pump Relay, having to jump it to run it
___________________________________
I am STUCK to say the least, bought a glossy turd if anyone can help, or have suggestions please let me know, ive been suggested by a few to replace the ECM, but i dont want to just throw money and pray i want results
Thank You!
 
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Blancotahoe

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Welcome to the forum!

Have you pulled the underhood fusebox top (that holds the fuses) to inspect and clean the harness connections that are underneath the fuse holders?
I have not checked that, will check when i get home from work, another thing i forgot to mention is the erratic gear changing, test driving it i stood on the gas (Was seeing if the CEL would pop on) and it would drop, and up a gear about 3 times before i let off (maybe 5 seconds max?)
 
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Blancotahoe

TYF Newbie
Joined
Mar 16, 2023
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Needing Help!
I have a 2007 Chevy Tahoe LT 5.3L V8
Ive owned it for 2 years after about a month of owning had a Cyl. 7 missfire, new plugs / wires, no fix, went down the entire rabbit hole and found a stuck valve, now i sit here today, absolutely stuck, still having a missfire (cyl 1 & 6), EVAP codes, And throwing a “No Communication” on every Control Module (ECM, TCM, BCM) everything i have done below
——————————————————————
• New Plugs & Wires
• New Injectors
• New Coil Packs
• New Cyl. Heads (Reconditioned)
• New Lifters
• New Lifter Guides
• New Push Rods
• New Throttle Body
• New K&N Intake
• New Catalytic Converter
• New O2 Sensors
• New Terminals
• New Fuses & Relays
• Replaced Entire Engine Wire Harness
• New Cam & Crank sensor
• New MAF Sensor
• New Intake Manifold Gasket
• Cleaned,Replaced,and Added Ground Wires
___________________________________
A few pointers to help that i have found out,
• All mentioned items have been tested
• I own an Matco Scanner, Multi-meter, etc to run tests
• When putting Scanner into OBDII port dash goes wild, and truck drops RPMs and Bogs/ almost dies
• Truck will sometimes retract Check Engine Light when driving
• Not getting power to Fuel Pump Relay, having to jump it to run it
___________________________________
I am STUCK to say the least, bought a glossy turd if anyone can help, or have suggestions please let me know, ive been suggested by a few to replace the ECM, but i dont want to just throw money and pray i want results
Thank You!
Another thing i forgot to mention for i was to irritated working on it, but some more symptoms to help diagnose
___________________________________

• “Hood Open” light occasionally comes on
• “Rear Access Open” Light occasionally comes on
• Doors Lock and Unlock when hitting a bump, or driving
• ABS Light will flash at times, since the new harness has been installed it only comes on when scanner gets plugged in
• Traction control light on
• “Service Stabilitrac” is on the dash
___________________________________
 

swathdiver

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Sounds to me like the BCM or underhood fuse block has gone bad.

Having said that, I would first hook up external power to the truck and then connect your scan tool and run diagnostics. I could be a bad battery after all.
 
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Blancotahoe

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Came out to the truck just now, battery showing 2v, jumped it off and going to run the tests
 
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Blancotahoe

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Update:
• Pulled all fuses, cleaned fuse block and connections
• Battery is completely shot, when another source of power was added the idle was smoother, check engine light took longer to come on (still cyl.1 & 6 had cyl 8 pop up for 2 missfires or so and went back to 0 instantly)
• CEL goes completely away at around 1.5 to 2k rpm, missfire data reads 0 on all cylinders when brought to said RPMs (with added power source)
 

Doubeleive

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my best guess besides the dead battery is you have a bad ground or short somewhere. I would start looking at the engine grounds for starters
 
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Blancotahoe

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What would cause my EVAP code, and my fuel pump relay to not get any power
 

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