Question about sensor replacement on 1991 Buick...

[gregk24]

Another post about the 1991 Buick Park Avenue. It was in the shop the other day for the stalling issue when warm. All I know is that they replaced "a couple sensors". A family member took it in and we don't have the work order to reference. We were peaking around the engine bay today after checking the coolant and noticed what looks to be a new sensor. I assuming this is one of the O2 sensors? Just wanting to confirm! Here is a pic....

 

[Trav]

Yep, front (or upstream for those who demand correctness) O2 sensor.

 

[53' Stude]

Yeah, that's one of your O2 sensors; looks like a "pre cat" or before the car converter sensor sir

 

[gregk24]

Ok thanks for confirming! Could this sensor in this particular location affect MPG?

 

[Nick1994]

Originally Posted By: gregk24
Ok thanks for confirming! Could this sensor in this particular location affect MPG?
Absolutely. Probably more than any other sensor in the car.

 

[javacontour]

Probably no sensor after the cat for a '91 which is pre-OBD-2. So there is probably just a single sensor on this vintage car.

But yes, that's the new O2 sensor.

 

[gregk24]

Great! Hoping this is what was causing the poor MPG's. He was getting probably around 12 MPG on average, maybe up to 15 on a good day.

 

[Nick1994]

Originally Posted By: gregk24
Great! Hoping this is what was causing the poor MPG's. He was getting probably around 12 MPG on average, maybe up to 15 on a good day.
One way to check the fuel mileage, fill it up and take it out on the highway for about an hour, or 60 miles and drive about 65 mph. Then fill it up and calculate the gas mileage. If it's 26+ I'd say there isn't a problem. If it's real low like 18, then there's a problem.

Worst case is you'd use about $5 in gas.

 

[gregk24]

Originally Posted By: Nick1994
Originally Posted By: gregk24
Great! Hoping this is what was causing the poor MPG's. He was getting probably around 12 MPG on average, maybe up to 15 on a good day.
One way to check the fuel mileage, fill it up and take it out on the highway for about an hour, or 60 miles and drive about 65 mph. Then fill it up and calculate the gas mileage. If it's 26+ I'd say there isn't a problem. If it's real low like 18, then there's a problem.

Worst case is you'd use about $5 in gas.


Yep! I've told him this is the best way to calculate MPG but he doesn't normally fill it up all the way. Just a little here and there as needed.

 

[BigD1]

Can't remember exactly, but I think if that sensor is bad it could put it in limp mode, which runs on the rich side, and causes the engine to consume more fuel. Might be a good idea to do an oil change if it has been running rich a long time, at least that's what I would do, but I am OCD!

 

[asand1]

Upstream O2 sensor is directly responsible for controlling Air/Fuel ratio. A bad sensor will cause lean running (hot, pinging, and bogging) or rich (black smoke, high fuel consumption, and poor running.

 

[Rhymingmechanic]

I could be seeing wrong because of the camera angle, but it looks like the O2 sensor wire is lying on the exhaust manifold.

Do any other sensors look new? There might be a sticker under the hood showing their locations.

 

[javacontour]

Originally Posted By: Rhymingmechanic
I could be seeing wrong because of the camera angle, but it looks like the O2 sensor wire is lying on the exhaust manifold.

Do any other sensors look new? There might be a sticker under the hood showing their locations.


It is a 91, with only a single sensor. No upstream vs downstream and no bank1 vs bank2. It's a single wire non-heated sensor.


People keep treating this as if it was an OBD2 car. It's not. It's pre-1996, so it's not OBD2.