Running LEAN! 96 5.0
Posting Guru
Joined: Sep 2008
Posts: 2,379
Likes: 2
You have 3 O2 sensors? That would make me think 2 are narrowband and 1 is wideband. If so, the wideband will have an output wire that reads anywhere from 0 to 5 volts. You can probe this wire while the motor is idiling and see if it changes when you rev the motor. That is what you should attach to a wideband gauge (and calibrate if necessary). It should read 5v when the O2 sensor is warmed up but motor not running. Then it'll change when you start the motor.
If you're going to monitor AFR, then get in there and connect this yourself so you can learn what it is you are using and how it works. It isn't much more difficult than wiring switches or the like. And you won't be at the mercy of the speed shop telling you what they did.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
OBD-2 trucks have 2 upstream narrowband sensors and a 3rd after cat sensor that's is different but I believe it's still a narrow band sensor.. it's different in that it's designed to slowly float between it's upper and lower range instead of rapidly switching back and forth.
Thread Starter
|
Elder User
Joined: Jul 2012
Posts: 769
Likes: 0
From: Poplar Bluff, MO
Pulled codes and it was secondary air injection so i dont know if that's relevant or not. But I can physically tell it's runnin lean because the throttle response is terrible and it doesn't go anywhere when I romp on it
Posting Guru
Joined: Apr 2011
Posts: 1,119
Likes: 1
From: Hartland, WI
The O2 sensor could be stuck lean, causing the computer to dump fuel. Poor MPG and performance will result.
Post-cat O2s are just like any other, the reason they move slowly or don't move at all is because the cat is using the stored oxygen to reduce the HCs and CO. The reason why the ECM commands the mixture to swing rich/lean is to provide oxygen for the cat, and to try to maintain as close to stoiciometry as possible.
Word of warning: There is a difference between an oxygen sensor and an air-fuel sensor:
Advanced air-fuel and oxygen sensor diagnosis - Automotive Service Professional
Post-cat O2s are just like any other, the reason they move slowly or don't move at all is because the cat is using the stored oxygen to reduce the HCs and CO. The reason why the ECM commands the mixture to swing rich/lean is to provide oxygen for the cat, and to try to maintain as close to stoiciometry as possible.
Word of warning: There is a difference between an oxygen sensor and an air-fuel sensor:
Advanced air-fuel and oxygen sensor diagnosis - Automotive Service Professional
Thread
Thread Starter
Forum
Replies
Last Post
tomtoc
1983 - 2012 Ranger & B-Series
8
Feb 19, 2007 06:58 PM
BLACK NITE
1987 - 1996 F150 & Larger F-Series Trucks
2
Apr 27, 2006 08:16 AM
