2001 gmc sierra with issues

[simmonsp5]

My truck will run fine for a few days and then all of sudden it will start spitting and sputtering and back firing. So far i have changed the purge valve, fuel filter and fuel pressure regulator and mass air flow. It's still doing the samething. Anybody know what could be causing this problem.

Thanks Phil

 

[Molson02536]

My truck will run fine for a few days and then all of sudden it will start spitting and sputtering and back firing. So far i have changed the purge valve, fuel filter and fuel pressure regulator and mass air flow. It's still doing the samething. Anybody know what could be causing this problem.

Thanks Phil

I am going to guess that you have a 5.3 vortec in your Sierra. The common issues that the 5.3 vortec is the knock sensors are located in the valley between the heads under the intake manifold.

Water collecting there after time will corrode the wires and short out or the knock sensors corrode also from water damage. When this happens, the PM gets faulty readings and will cause the timing of the engine to change for the worst, causing the issues you have described.

You can have the Sierra scanned to see if there is a code in the history to confirm that it is a knock sensor (P0332) before you have them replaced and take note there are two sensors.

http://www.jimfancher.com/sierra/p0332.htm

Good luck and keep us posted.

Molson02536