air pump effect on 02 sensor
Thread Starter
Racer
Joined: Jul 2001
Posts: 368
Likes: 0
From: Tampa FL
air pump effect on 02 sensor
The o2 sensor measures air/fuel ratio. The air pump injects air into the exhaust manifold upstream of the o2 sensor. Since the air pump adds fresh air to the exhaust stream, it should increase the air/fuel ratio measured at the sensor. I'd think that the computer would be calibrated to this. By removing the air pump system, would you be throwing off the o2 readings? With the fresh air no longer being added to the exhaust, wouldn't it cause the computer to think "rich" and react by leaning the fuel supply?
I've searched the web and gotten some great info on o2 sensors and air injection systems, but nothing about the relation between the two.
I hope someone can provide some input. Thanks in advance.
I've searched the web and gotten some great info on o2 sensors and air injection systems, but nothing about the relation between the two.
I hope someone can provide some input. Thanks in advance.
Burning Brakes
Joined: Apr 2001
Posts: 904
Likes: 0
From: Langley, BC, Canada
Re: air pump effect on 02 sensor (TJR)
I know when you go wot, the air diverts from exhaust and dumps directly into the air cleaner assembly..My car had a leaky diverter valve when i bought it, it would sometimes back fire and ran rich from the fresh air, being introduced into the exhaust when it should not have been..the air is delivered to the manifolds when the car is cold, leaning the mixture to induce a rich condition for warm up. when its warm, the air is diverted to the cat, past the o2 sensor, so it has no effect of mixture..hope this helps..
Racer
Joined: Mar 1999
Posts: 292
Likes: 0
From: Vienna VA
Re: air pump effect on 02 sensor (TJR)
On my 90, air stops getting pumped into the exhaust manifold at warm up. When the ECM goes into closed loop where it is using the O2 sensor for feedback, air is being pumped into the cat only. Air pump has no impact on O2 readings.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: air pump effect on 02 sensor (Carl90)
That's it. The diverter dumps air into the exhaust manifolds during warmup to help heat the O2 sensor to accelerate closed loop running. After that air is dumped into the cat, or to the outside. Once in closed loop mode air is not injected into the exhaust manifold, unless there is a fault in the diverter system.
Thread Starter
Racer
Joined: Jul 2001
Posts: 368
Likes: 0
From: Tampa FL
Re: air pump effect on 02 sensor (nsimmons)
...when its warm, the air is diverted to the cat, past the o2 sensor, so it has no effect of mixture..hope this helps..
