2004 Tahoe 5.3L Help

I’m scratching my head, what’s my next step?
It was parked for a couple years after cam bearing 3 spun and then the fuel went bad.
I rebuilt the engine, new knock sensors and harness, cleaned K&N air filter, cleaned the MAF sensor, fuel filter (I couldn’t blow air through the replaced one it easily).
The two confirmed codes are P0332 and P0327, bank 1 & 2 knock sensors. I had read the oil from a K&N filter can cause a film on the MAF sensor leaning the engine and causing knocks, I assume the filter would have the same effect. I suspect the injectors. I just ran a bottle of HEET and SeaFoam in 5 gallons of gas through it.

Did you replace the knock sensor wiring harnesses, they have know to go bad.

Also need to look at a live data stream to see what the fuel trim is

THE PUNISHER said:

Did you replace the knock sensor wiring harnesses, they have know to go bad.

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And get pinched under the intake when installing.

I have never seen an air filter of any style cause a lean condition setting knock sensor codes. That is not how that system works.

Mike Overlay said:

And get pinched under the intake when installing.

I have never seen an air filter of any style cause a lean condition setting knock sensor codes. That is not how that system works.

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This man is a 5.3 genius. Listen when he talks

THE PUNISHER said:

Did you replace the knock sensor wiring harnesses, they have know to go bad.

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I did, and made sure it wasn’t pinched/grounded by the intake.

Mike Overlay said:

And get pinched under the intake when installing.
Can I see the fuel trim with an Actron the PIM readings?
I have never seen an air filter of any style cause a lean condition setting knock sensor codes. That is not how that system works.

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I pinched the first harness , made sure it didn’t happen a second time.
I saw a warning about an oily film build up on the MAF sensor, especially if the filter’s heavily oiled.

Fuel pressure is 50psi Key On Engine Off and when accelerating. 42psi at idle.
At idle in park


Idle in park


@ 2k rpm in park





Any thoughts?

Does the upstream sensors (before cat) read high the low fast? .800-.100 should be switching fast. Ones behind cats (post) should be switching slower than the fronts.

Have you got the two harnesses plugged to the right sensor. I know zero about the 5.3 but I once had a Fiat eng that came from the factory with the upstream and down stream noxs sensors plugged up backward. Upsteam harness was on down stream sensor and vice versa.

Where did the knock sensor and harness come from?

That sytem is relatively simple. They measure a frequency that ripples thru the block when a knock occurs. The data screen shots you show are really of no help with a knock sensor issue.

The knock sensor are used by the pcm to correct for spark knock, changing the ignition firing timing either by advancing or regarding the timing. You will not get knock sensor codes when lean or rich condition occurs.

The codes p0327 and p0332 are when the knock sensor system has a fault. The fault is going to be either bad sensors, bad harness, damaged sensor harness or a break in the wiring from the harness connector on top of the manifold to the pcm.

The lean condition that you suspect will cause p0171/p0174 codes to set. And since those codes are not present and the screen shots show the data parameters are normal, stop chasing that thought process.