Fuel problems or o2 sensor

[darkiller_666]

my girlfriend bought me a narrowband air/fuel ratio gauge. she doesnt know the difference between wideband or narrowband, but it was free and im sure she would have been upset if i just let it sit in garage. So i hooked it up, it almost allways reads lean, sometimes moving slightly to the stoich after light throttle or shifting gears. I dont know if this is caused by a bad o2 sensor or if my engine just isnt getting proper fuel. Boost is set to a minimum and regardles of correction on the Safc the Air/fuel allways stay low lean during idle and throughout most driving conditions. didnt know if i should think fuel pump injectors or something fuel delivery related or a bad sensor. Shoot me sum knowledge.

 

[grnchevyz]

Easiest way of telling if its a bad sensor is monitor the voltage on the tapped line with a multimeter. If it reads fine then I'd look more towards a bum gauge.

 

[allrice4g63]

no offense but i wouldnt use them narrowbands for anything for maybe umm paper weight. They tell you nothing but sure do look pretty.

 

[darkiller_666]

well obviously having it showed me that the signal my ecu was receiving for my fuel trims is blatantly wrong. is that useless. i understand its not as accurate as a wideband. but its more accurate then guessing by the sounds of the car...

 

[grnchevyz]

A narrowband will indicate up to a certain degree of accuracy the a/f ratio. It is however not to be used for proper tuning.

I would check the output of the O2 sensor with a multimeter to rule out a bum gauge.

Also, what wire do you have tapped for the gauge?

 

[darkiller_666]

number 76 on the ecu the top wire of the two white ones in the middle of the top plug towards the side of the firewall. i hope that makes sense. like i said the gauge does fluctuate some. but almost always lean. I am also getting horrible gas mileage, about 10-14 a gallon. I am not trying to tune with the narrowband i dont even run with my boost higher then stock. The car is currently a DD and i need to make sure it lasts until i have my build funded entirely and a second car so it can be down for some months.

 

[darkiller_666]

what would a proper signal from the o2 sensor read?? im assuming i can check the white wire straight from the sensor or the number 76 wire from the ecu with the multimeter.

 

[grnchevyz]

The ranges should be as follow on that wire:

LEAN RANGE: (.050 to .249V)
STOICHIOMETRIC RANGE: (.250 to .749V)
RICH RANGE: (.750 to 1.000V)

See if it changes as you put the accelerator down, if it does the gauge is bum if it doesn't, change the sensor.

Hope this helps.