The 91 Yota 4x4

Hi,

Can anyone out there please advise how to change the Oxygen sensor in a 1991 Toyota Pickup 4x4 V6?

My damn check engine light keeps coming on once i reach about 20mph and i feel a slight loss of horsepower, and it is preventing me from getting smogged / registered hear in Cali. My mechanic says its probably the Oxygen sensor, but that it will take about 4-5 hours of labor to get to it. Does this sound right?

Any advice would be much appreciated.

Also, if the sensor is still good, any idea what could be causing it to trigger the error? Possibly exhaust?

Thanks.

Jake, Newport Beach, CA

Ardent

Replacing the O2 sensor(s) should be easy. (CA 4Runners have 2, i believe one's before the cat, and one aft.) When I did mine, (I only have 1) it only took around 30 min. It's just two bolts each. As long as there not rusty, it shouldn't be difficult.

4-5 hours sounds pretty ridiculous, unless there's something different about your pickup than mine. The O2 sensors are located on the top of your exhaust pipe, near the driver's side door.

DupermanDave

I would say an hour tops. Try taking your truck to another mechanic. I've replaced an O2 sensor in my suzuki sidekick and it was very similar to the way it is with the 4runners and pickups.

abecedarian

Just 'cause the mech says it's "probably" the O2 doesn't mean it is.
Pull the trouble codes and check for yourself.
But if it is the O2, you could do both (if you have two) by yourself in about 1.5 hours including the trip to the parts store... IF the nut's come off. So make sure you soak them in penetrating oil (PB Blaster, 3-in-1, WD40, etc.) the day before you work on it, and try to not drive it.

The 91 Yota 4x4

Thanks for your answers. Abe - how do you pull the trouble codes and check myself?

Why not drive the day before? Just curious.

There also seems to be a whistling sound for a few seconds after switching gears. Its hard to isolate where its coming from as i'm driving, but sounds like from the rear. Could this be a related problem?

-Jake

abecedarian

I'm quoting the PM you sent me here so we can bring this back for others to chime in on. My response will be at the bottom.
If you can isolate between front or rear where the thump is coming from, that would help, but without more information, it's possible the rear wheel bearings are worn and the axle is shifting during turning causing the thump.

As for 25, 26 and 52...
25 is Lean fuel mix
26 is Rich fuel mix
52 is no signal from knock sensor

I'd suggest clearing the codes by disconnecting the battery for a few minutes then reconnecting it and drive it for a while to see if the codes come back. Then worry about them.