2007 Tahoe 5.3l AFM DOD delete thread

[Taheezy_88]

Alright guys after a long process and having to put off the project due to traveling and etc... I finally got it started and running. I do have three things that concern me.

1) Stabilitrak light is still on. Why could this be?

2) p300 engine misfire code. This worries me any reason why I could be getting this misfire? Put new plugs in this morning before start up

3) oil pressure fluctuates. 40 when I rev the engine but drops low when idle. Any opinions? (Posted pics)

 

[kbuskill]

#1... Stabilitrac light could be/probably is on because of the misfires.

#2... Could be dirty injectors, could be a bad coil pack harness, could be a bad coil pack or plug wire, could be a burnt valve although that is unlikely as the machine shop would have probably caught it. I always have them pull a vacuum on the heads/valves to make sure they are sealing well.

#3... Could be bad cam bearings but I would check the seals on the towers under the VLOM/valley cover. Not sure if you replaced/removed the screen under the oil pressure sensor.

I didn't go back and reread the 10 pages to see if any of this was already covered... just the first things that came to mind.

 

[Taheezy_88]

#1... Stabilitrac light could be/probably is on because of the misfires.

#2... Could be dirty injectors, could be a bad coil pack harness, could be a bad coil pack or plug wire, could be a burnt valve although that is unlikely as the machine shop would have probably caught it. I always have them pull a vacuum on the heads/valves to make sure they are sealing well.

#3... Could be bad cam bearings but I would check the seals on the towers under the VLOM/valley cover. Not sure if you replaced/removed the screen under the oil pressure sensor.

I didn't go back and reread the 10 pages to see if any of this was already covered... just the first things that came to mind.

 

[Taheezy_88]

2) plugs and wires are new. I'd have to replace coil packs, injectors would running a fuel system cleaner fix that?

3) I did remove the small oil screen filter because it wasn't fitting with the new vlom and read somewhere on a GM site that running without doesn't hurt but of course I could be wrong or that source.

What should be my first steps to solving the issues? Pull VLOM check towers? Replace Coil packs, and try to reinstall the oil filter while I have vlom pulled

 

[Taheezy_88]

Would running straight headers cause this?

I don't have the y pipe bolted up to the headers yet. I was also getting a lean code. Could it be because the o2 sensors are not hooked up/y-pipe and the engine running lean cause the misfires?

 

[kbuskill]

Would running straight headers cause this?

I don't have the y pipe bolted up to the headers yet. I was also getting a lean code. Could it be because the o2 sensors are not hooked up/y-pipe and the engine running lean cause the misfires?

A good scanner that can show misfire history would help narrow down the culprit. You could try swapping coil packs to see if the misfire moves with the coil pack.

You don't have your upstream O2 sensors hooked up? Or downstream O2 sensors?

 

[Taheezy_88]

Downstream I assume the ones that hook on the cats.

 

[kbuskill]

Downstream I assume the ones that hook on the cats.

Downstream O2s don't affect the fuel trims.

 

[wsteele]

If the upstream O2 sensors aren’t there or one has a fault, it can lead to misfires.

If you have a scan tool, try and find the cylinder misfire count page and watch it while running the engine. You can see real-time which cylinders are misfiring and how often. It can help you isolate the problem to one bank or the other and after that, which cylinders.

If both banks have a lot of misfires, that too can help in isolating the issue.

 

[Taheezy_88]

Upstream

 

[Taheezy_88]

The 02sensors closest to the headers so my upstream sensors are unplugged. Let me get the ypipe and upstream 02 sensors hooked up. I hope that's the issue what yall think?