I've got a '91 RS 305 Automatic and want to replace my Oxygen sensor. Can anyone tell me where its located? Hard to get to? Will I have to go under the car to get to it?

tnx
Tim

 

It is on the driver's side exhaust manifold. Just open the hood and stand over the driver side fender. Look down and you should see it. You need a 1" or 15/16" closed end wrench I believe. It may be easier to change it from the bottom but I think it can be done from the top.

 

What Shifty said. Usually, you can change them from teh top:

 

I have heard a bad sensor will cause bad gas mileage. We have a 305 TBI 91RS that sucks the gas. All standard tune-up items replaced.

 

DEFINITELY. probably the #1 thing that will hurt mileage. When I bought my car it had a bad o2 sensor, and got maybe 9 mpg and ran really rich (black smoke out the exhaust). I changed it and it shot up to about 20.

 

Vader and Shifty:

Really appreciate the info, esp the pic. Going to change my sensor tomorrow. Really hard to see it on my car but can see it thanks to you pointing out the location with the pic.

Now, if I can ever get my speedometer working again!

Tim

 

Speedo? (Not the swimwear.)

If I'm correct, the '91 Camaros finally got an electronic speedometer and used the VSS at the transmission like the Firebirds had since 1986. Make sure your's is connected:

 

Vader,

Yep, it's connected. I replaced mine with another one that I got at a salvage yard. That may be my problem. Not sure. I was getting a VSS error after hooking my laptop up to the car along with an oxygen sensor and tps low error. Today I replaced my oxygen sensor and disconnected the battery and reconnected and now all 3 errors are gone. BUT, my speedometer is still not working and I was not getting a reading in the program on my laptop either for speed. Does that mean it's definately a wiring problem?

Thanks much for the help.
Tim

 

if the converter has been removed. I have heard it will send a false reading if the converter has been removed. I was also told you can buy a "fake" 02 sensor replacement that will fool the computer. The car gets really bad gas mileage.

 

The fake o2 sensor is for the o2 sensors that are after the cat. We dont have those sensors on our cars. You dont want to use that for the sensor that is in front of the cat.

 

if I don't have a converter ? It sounds like I should

 

It isn't necessarily a wiring problem. The VSS is operated by a steel drive gear pressed on the tailshaft, and a plastic driven gear on the VSS thimble. Make sure the plastic gear is in place and intact. When you remove the VSS to check that, look inside the housing to see if the steel drive gear is centered in the opening, so it will mesh the driven gear properly.

Another thing you can do is connect the VSS electrical connector, turn on the ignition, and have an assistant watch the speedometer/odometer while you manually turn the VSS thimble.

 

If you have headers...will this sensor be in the same location?

 

Nope. Not necessarily. It could be mounted anywhere.

 

This is true. I bought some Hedmen's and had to drill the hole in driver's side and weld in the insert for my sensor.

 

I guess I will hunt for an addapter that looks like the one in this picture. I am thinking my O2 Sensor is off and needs replacing as my exhaust has a rich gas like smell to it.