I have a four wheel drive Chevy Silverado 1500 with a vortec 5.3 motor in it. The truck has 59,800 miles on and was manufacturer in Canada as I found out this makes a difference on the 02 sensor. I have been fighting a lean fuel code for the past 2 months and can't seem to get rid of it.
I have change out the following parts:
1) air filter
2) fuel filter
3) Idle air controler (truck was pulsating on cold start ups until it reach operating temp.)
6) both upstream 02 sensors.
I have taken it to a repair shop and they spent an afternoon trying to come up with something wrong with it and they can't. They stated the vacum was good, they smoke the engine and could find no leaks around the intake or injectors. They shut off individual pistons and all the injectors seem to working. They did state as they have no way of testing the flow of the injectors. They check the other sensors and found no issues.
I have watched when the light comes on for the past 3 times and it is always when the truck reaches 180-185 degrees. Friday after they reset the computer the light stayed off till this moring on my way to work.
So in summary my question is what is my next step. The repair shops says it might be the computer going or I need to take it to a dealership to get a complete computer flash. They also recommended a motor vac to clean the intake injectors and intake.
Any help would be greatly appreciated.