2003 Silverado Problems

[Foxtrot06]

I have a 03 Silverado that starts up and runs fine but after awhile it starts dropping cylinders on one bank, like it was leaning out one bank, it then proceeds to stall. O2 Sensors have been replaced, fuel pressure is good, plugs and coil packs are good. 

[asilverblazer]

Codes?

Engine?

[Foxtrot06]

5.3L.

No new codes from what I remember. Original codes were p0300 I believe. Unfortunately I don't currently have quick access to the truck to check.  

[asilverblazer]

How are you able to determine it is only one bank?

 

All four cylinders on one bank?

 

Clogged catalytic converter?

[Foxtrot06]

I'm not the one that did the testing just relaying what I was told. Wouldn't a clogged cat cause this issue from start up not after running for awhile?

Edited February 9, 2024 by Foxtrot06

[asilverblazer]

2 hours ago, Foxtrot06 said:

I'm not the one that did the testing just relaying what I was told. Wouldn't a clogged cat cause this issue from start up not after running for awhile?

Maybe-there just aren't that many factors that will cause a problem on one entire bank of cylinders and only that bank.

 

You've already replaced the O2 sensors - were all 4 replaced?

 

What condition indicated the need to replace them?

 

It could be that the upstream sensor on the problematic bank is defective - no way to know without a trouble code or live data stream.

 

Could be an injector leaking badly on that bank sending a bunch of raw gas into the exhaust messing up the O2 reading to the point it leans out all the others injectors.

Edited February 9, 2024 by asilverblazer

[asilverblazer]

If I were to speculate further than the information you have. It probably isn't one bank, its probably a general miss fire (P0300) happening on all the cylinders. It starts up and runs fine - cold. Once the engine warms up and goes into closed loop the problem starts. 

 

Since there are no other codes indicating a sensor performance issue the PCM cannot properly adjust the fuel injector pulse width for whatever amount of air is entering the cylinders. 

 

This means either the incorrect air amount is entering or the incorrect amount of fuel is. 

 

The O2 readings will (should) indicate which component there is too much/little of.

 

Inspect the air intake track including the MAF sensor.

 

I mentioned fuel injectors earlier, but the likely hood of several of them being faulty at once is minimal. You say fuel pressure is good, so that would lead me to think it's an air intake problem. Plus the engine probably would have issues in open loop if the fuel system has a mechanical deficiency.

 

You can also probably rule out any ignition problems, those would be present when cold.

 

This all could lead back to O2 sensors - there is an internet rumor that you should only use AC/Delco sensors or will run into issues. 

 

Any modifications made to the truck?

Edited February 9, 2024 by asilverblazer