I tried to do what the tech article explained on tuning fuel pressure w/ the O2 sensor but had some problems. The reading was way too erratic and jumped all over the place on my DVM. Why would this be?
Thanks. Adam

 

A narrow band O2 sensor, like the one installed in your eng, will only tell you if you're above or below 14.7:1 air/fuel ratio.
If it's reading .45v or below it's leaner than 14.7:1. It it reads over .45v, you're running richer than 14.7:1. The ecm is constantly correcting the mixture based on readings from the O2 sensor. That's why the readings are all over the place. It's either a little too rich or a little too lean all the time when in closed loop mode. If all is well, the AVERAGE mixture will be 14.7:1...
The amount the voltage varies from .45v is not a good indicator of actual mixture.

You need a wide band O2 sensor to get accurate readings on your mixture, especially as you move away from 14.7:1, like under hard acceleration where it should be richer.

 

you are all over the place because the o2 is picking up lean or rich cyl from a leaky or weak injector.. get a scan tool and see what the blm's are. a balanced set of injectors will read about 128 left and right. You need level readings first then you can tweek fuel pressure using the o2.. lower numbers would indicate a lean engine, higher would be rich. adjust the fuel pressure till the blm's are at that 128.

 

What are BLM's and what kind of scanner do i need?