help diagnose

[Smokinhot]

Ever since I did the 6.0 swap I've had p2681 and now I've been getting a code for low voltage on my knock sensors.

The truck runs normal when the codes are off/cleared but when they come on I go rich. Its driving me nuts!! I cleaned the block connection for the ground wire coming from the battery, and the 2 on the backside which one is in the trans harness and the other is in the loom for the passenger side injectors.

any suggestions on what could cause this problem?

another symptom that leads me to a ground issue, my voltage drains down on certain things. just putting up the windows or running the defroster. It'll spike and then come back up.

I don't recall nor have I seen any pinched wires

Click to read more...

 

[HILROD]

I don't remember the codes it had, but my buddies Tahoe had the same trouble with bad knock sensors.

 

[Smokinhot]

ok, so here's another question

How do I remove a knock sensor that wont come out? I tried replacing the back one, but when I broke it loose it just spins but doesn't unscrew. I don't know what they are called but I think there is something like this pressed in the block which the knock sensors screw into and its just spinning but doesn't come out

that's the knock sensor location on my 4.8

 

[HILROD]

Pull the valley cover and see if you can see it better. Sounds like that spinning could be the ground issue.

 

[Eagle]

I'm guessing the spinning is happening with the knock sensor itself, not the block or this possible insert you speak of (although I'm pretty sure its not pressed in). If that's the case, then the sensor is almost certainly bad.

Do what you have to get it out. It's pretty fine threads too... so you'll have to turn for a bit to get it to come out....

How tight was it?

 

[Smokinhot]

tight enough I needed a breaker bar

I can't take the valley cover off till it comes out. I was loosening it up for a bit and it didn't come out.