I have a 5.9 Magnum and runs a little lean. How do i make it run richer without a programmer or chip?

 

The fuel injection is controlled by the computer, so as far as I know the only way to change it is with a programmer.

 

How old is your pre-cat O2 sensor?

 

Why do you want it to run richer? Do you have the stock intake system on it still? If so it should be running a little more on the rich side. Generally they run at around 14-15 A/F ratio. If you lean it out to around 11 you can make more power. But you'd need to reprogram the computer, and you'd also need a wide band O2 sensor to read it accurately.

 

How did you make the "runs a little lean" determination?

 

How do you know it runs a little lean?