6.0 bogs at full throttle

Rocky Adams · December 28, 2021

3 minutes ago, CamGTP said:

Knock sensor failures are common. The rear sensor hole fills up with moisture and ruins the sensor and harness most of the time. New OEM sensors and a new harness usually always fixes the problem.

Because they are under the intake manifold doing what pizza man said wouldn't even be something I would consider doing for the amount of work that has to be done.

Ok, so just attempt to replace them and see from there?

Supreme Pizza · December 28, 2021

3 minutes ago, Rocky Adams said:

Ok thank you. Not to familiar with the octane world. Do you mind if I keep in touch with you for some later on questions?

Ya, keep in touch if ya want, but I recommend getting info from others on this site as well. I believe that I am correct, but that doesn't make it so. Others will inevitably have other idea or opinions.

What I can say, is that if you are increasing the performance of your motor, you will need to consider the octane rating of your fuel.

As for knock sensors, they are pretty basic, but also very important. They are basically microphones, listening for a certain sound, and they ****** the timing if your getting per-ignition sounds inside the motor. Pre-ignition will destroy the motor before too long if its not remedied. Its best to read about octane and what it is, read about knock sensors and how they work, etc.

When the knock sensors failed on my 2002, I left them in place and threaded some new ones into the front of the head, and then cut/spliced wires to hook them up to the harness.

Rocky Adams · December 28, 2021

5 minutes ago, Supreme Pizza said:

Ya, keep in touch if ya want, but I recommend getting info from others on this site as well. I believe that I am correct, but that doesn't make it so. Others will inevitably have other idea or opinions.

What I can say, is that if you are increasing the performance of your motor, you will need to consider the octane rating of your fuel.

As for knock sensors, they are pretty basic, but also very important. They are basically microphones, listening for a certain sound, and they ****** the timing if your getting per-ignition sounds inside the motor. Pre-ignition will destroy the motor before too long if its not remedied. Its best to read about octane and what it is, read about knock sensors and how they work, etc.

When the knock sensors failed on my 2002, I left them in place and threaded some new ones into the front of the head, and then cut/spliced wires to hook them up to the harness.

Okay. Thank you.

Supreme Pizza · December 28, 2021

18 minutes ago, CamGTP said:

Knock sensor failures are common. The rear sensor hole fills up with moisture and ruins the sensor and harness most of the time. New OEM sensors and a new harness usually always fixes the problem.

Because they are under the intake manifold doing what pizza man said wouldn't even be something I would consider doing for the amount of work that has to be done.

I don't think he has a knock sensor failure issue. The knock sensor bypass is to verify that detonation is the issue. I agree, don't pull the manifold. I should be more clear, I agree.

OK,

Find the black and green wires at the back of the upper intake manifold.

Cut both wires.

Splice more wire onto those to make them longer (harness side, not sensor side).

Connect the new wires to the new knock sensors.

Ground the new knock sensors to the block using wires.

Run the engine to see if the problem goes away.

Remove the new wires and sensors.

Reconnect old wires to old sensors.

This will tell you if pre-ignition/ping/spark knock is the issue.

If the problem was fixed with the test, then you have pre-ignition/ping/spark knock.

If the problem did not go away, then you do not have a pre-ignition/ping/spark knock problem.

Edited December 28, 2021 by Supreme Pizza

CamGTP · December 28, 2021

GM only has 3 codes for knock sensors on those trucks.

P0325 Knock Sensor 1 Circuit

P0327 Knock Sensor 1 Circuit Low

P0332 Knock Sensor 2 Circuit Low

A higher octane fuel isn't going to fix a circuit code. The only thing higher octane can do is lessen the knock or completely remove knock that was present. These LS engines can ping their brains out on garbage fuel and never set a code.

Supreme Pizza · December 28, 2021

Since he has an ignition timing issue, with engine modifications, I suspect that octane is an issue.

The test that I described would confirm that diagnosis.

Whats causing the timing to ******? My guess would be the knock sensors. Whats causing the knock sensors to trigger the computer to ****** the timing?

Pre-ignition.

If that's the case, then removing pre-ignition as a possible cause (by bypassing / isolating the knock sensors), then we would know for sure if the fuel quality is the problem.

If the timing problem is still there with the knock sensors bypassed, then the knock sensors and fuel quality have NOTHING to do with the timing issue, and then it must be electrical. Defective crank sensor, computer programming, etc.

But I could be wrong.

Supreme Pizza · December 28, 2021

2 minutes ago, CamGTP said:

GM only has 3 codes for knock sensors on those trucks.

P0325 Knock Sensor 1 Circuit

P0327 Knock Sensor 1 Circuit Low

P0332 Knock Sensor 2 Circuit Low

A higher octane fuel isn't going to fix a circuit code. The only thing higher octane can do is lessen the knock or completely remove knock that was present. These LS engines can ping their brains out on garbage fuel and never set a code.

Agreed. But he is not getting any knock sensor codes. He is having timing issues. Which I suspect are caused by the knock sensors doing what they are designed to do - ****** the timing.

CamGTP · December 28, 2021

Perhaps read his first post again. This thread turned into 15 posts too long because of that.

Supreme Pizza · December 28, 2021

You cant use the phrase "r3tard the timing" without it being censored?!?

Ok OK, he is having problems with cylinder firing before the piston has gotten close enough to top dead center .... Is that going to be censored??

Supreme Pizza · December 28, 2021

OK, I will take a look. If Im wrong, Im wrong. Back in a sec.

Rocky Adams · December 28, 2021

17 minutes ago, CamGTP said:

GM only has 3 codes for knock sensors on those trucks.

P0325 Knock Sensor 1 Circuit

P0327 Knock Sensor 1 Circuit Low

P0332 Knock Sensor 2 Circuit Low

A higher octane fuel isn't going to fix a circuit code. The only thing higher octane can do is lessen the knock or completely remove knock that was present. These LS engines can ping their brains out on garbage fuel and never set a code.

So basically what’s happening is my knock sensors are bad. So they are over

sensitive causing it to r3tard the timing?

Supreme Pizza · December 28, 2021

7 minutes ago, CamGTP said:

Perhaps read his first post again. This thread turned into 15 posts too long because of that.

DAMN!

Your right man, I missed that part.

CamGTP is correct. Good work catching the mistake.

Somehow I read it as NOT having any codes...

That changes everything.

In that case, forget everything I said.

I reluctantly add the following advise:

buy the $20 sensors and harness kit online.

Thread the new sensors into the front of the heads (they thread right in, same hole size)

Disconnect the old sensor harness, and plug the new sensor hardness into the vehicle harness.

Plug the new harness into the new sensors.

Leave the old sensors and harness in place, and don't pull the intake manifold.

It takes about 20 minutes total.

I did this on my 2002 Suburban, a few years ago, and it still runs great with no codes.

See pics:

Supreme Pizza · December 28, 2021

16 minutes ago, Rocky Adams said:

So basically what’s happening is my knock sensors are bad. So they are over

sensitive causing it to r3tard the timing?

If you getting knock sensor codes, your sensors are most likely bad. Its very common.

You can barely change the front sensor without pulling the manifold, but the rear cannot be done without pulling the manifold.

The sensors sit in an area were they get wet and then sit in water for says. Bad design.

Now that I think of it, I had to replace both sensors on my 2002, which I installed in the front of the head, and my 2003 had one sensor fail, which I installed in the front of the head. Super common problem.

When the sensor fails, the computer goes into fail safe mode for those sensors. In order to keep the motor from blowing up, it has no choice but to put it into full r3tard. If it did not, the motor could fail pretty fast.

So basically when the sensor stops reporting information, the computer assumes the worst case scenario, and does everything it can to prevent detonation, short of shutting off the motor. So the timing goes to full r3tard.

Edited December 28, 2021 by Supreme Pizza

Rocky Adams · December 28, 2021

10 hours ago, Supreme Pizza said:

If you getting knock sensor codes, your sensors are most likely bad. Its very common.

You can barely change the front sensor without pulling the manifold, but the rear cannot be done without pulling the manifold.

The sensors sit in an area were they get wet and then sit in water for says. Bad design.

Now that I think of it, I had to replace both sensors on my 2002, which I installed in the front of the head, and my 2003 had one sensor fail, which I installed in the front of the head. Super common problem.

When the sensor fails, the computer goes into fail safe mode for those sensors. In order to keep the motor from blowing up, it has no choice but to put it into full r3tard. If it did not, the motor could fail pretty fast.

So basically when the sensor stops reporting information, the computer assumes the worst case scenario, and does everything it can to prevent detonation, short of shutting off the motor. So the timing goes to full r3tard.