Need help!!!

MalcDogg · Mar 8, 2021

Hey guys need some help I’m new to this forum
I have a 2008 Chevy Tahoe 5.3 LT
Got a misfire Cylinder 1 change plugs wires coils and injector still getting code
I noticed it’s not switching from v8 to v4 also traction control and stability message on dash board also MIL indicator code
Can anyone help??????????

OR VietVet · Mar 8, 2021

Welcome to the forum from Oregon.

Members here will chime in with AFM info that could be related to your problem. I would still want to do a compression test on at least #1 and #3 cylinders, if not all 8 cylinders.

MalcDogg · Mar 8, 2021

PNW VietVet said:
Welcome to the forum from Oregon.

Members here will chime in with AFM info that could be related to your problem. I would still want to do a compression test on at least #1 and #3 cylinders, if not all 8 cylinders.

did a compression test as well looks like the valve isn’t moving but not to sure I’m getting spark because it shocked me

Doubeleive · Mar 8, 2021

since when does a 2008 have afm?

OR VietVet · Mar 8, 2021

Doubeleive said:
since when does a 2008 have afm?

I thought the AFM was available starting in 2007?

"Back in 2007, GMC introduced a feature for its motors, called the active fuel management system, or AFM. The company implemented it to increase fuel economy, get better horsepower, and more torque."

wsteele · Mar 8, 2021

I think this is a duplicate thread. It is going to get very confusing very fast unless a mod deletes one.

On the problem at hand, are you getting a #1 misfire code (P0301) on a scan tool?

When you say the valve isn't moving, what do you mean? Did you pull the valve cover and see one of the #1 rockers not going up and down?

1BADI5 · Mar 8, 2021

Doubeleive said:
since when does a 2008 have afm?

My '08 LTZ had it.

1BADI5 · Mar 8, 2021

Well the AFM is on cylinders 1, 7 and 4, 6 - so we're on the right track.

Could be a stuck AFM lifter or the solenoid for cyl #1 on the VLOM is dead.

- Both would account for a PO301.

- Low or lack of oil pressure registering to the cyl #1 solenoid

- An inactive solenoid would also contribute to the AFM not activating as a failsafe.

You're going to need diagnostic tool that can really get into the PCM and test functionality of the AFM

Doubeleive · Mar 8, 2021

PNW VietVet said:
I thought the AFM was available starting in 2007?

"Back in 2007, GMC introduced a feature for its motors, called the active fuel management system, or AFM. The company implemented it to increase fuel economy, get better horsepower, and more torque."

I have seen conflicting info on this, like that some engines had afm but it wasn't turned on, that it didn't start until 09, the hybrids had it first or something etc, etc

wsteele · Mar 8, 2021

Doubeleive said:
I have seen conflicting info on this, like that some engines had afm but it wasn't turned on, that it didn't start until 09, the hybrids had it first or something etc, etc

To my knowledge, all the 5.3L had AFM starting the 2007 model year. Mine is a 5.3L 2007 ands has it.

Need help!!!

MalcDogg

Member

OR VietVet

Multnomah Falls

MalcDogg

Member

Doubeleive

Wes

OR VietVet

Multnomah Falls

wsteele

Full Access Member

1BADI5

1BADI5

Doubeleive

Wes

wsteele

Full Access Member

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