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DYI steps please - 97 Pathfinder Oxygen Sensor and Throtle Position Sensor

7254 Views 9 Replies 5 Participants Last post by  billhappy
Hello folks,
I have been getting a terrible gas millage on my 97 Pathfinder (12 MPG city), so I want do some maintainance. I am planning on replacing the plugs, front oxygen sensors and throtle position sensor (Which I know is bad). Alas, I have never done those, and would like to know.

So, can any of you nice folks point me to a step by step instruction on how to change my oxygen sensors, and if it is DYI-able, the throtle position sensors? Otherwise, what is a fair rate at the mechanic? (Autozone price O2 sensor - 60, TPS - 85).

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Thanks for the replies.
Changing the spark plugs went alright except the last one at the back of the engine which was a bit hard to reach.
I read in the Chilton manual (which I borrowed from the library, did not know they kept those till yesterday) that the pre-cat oxygen sensors are the ones used to determine the fuel-air mixtures, hence why I wanted to change them. @underling: you are right. I can see the front O2 sensors (in the hood) and especially the driver side seems tricky to get to. Has anybody tried to change the pre-cats that themselves?

The TPS is from an error code (Actually two codes with same explanation). I have ordered the parts for that as well. Will see how that goes and report.
I changed the spark plugs and the air filter a couple days ago.
I changed the Throttle Position Sensor myself (because of a code), which seemed fairly easy to do, and is plainly accessible. Adjusting it might be a bit tricky. I hope I have got it right.
I changed the front two oxygen sensors. I bought the parts from Murray's Auto Parts, which matched Autozone's price and gave me 5% on top of that. I took them to my mechanic which charged me for an hour worth of labor. The front two are indeed tricky and hard to reach, so I am glad I took it to the shop.
I filled up my tank this morning, and am waiting to see if there is any improvement.
Thanks for your help.
Report 1:
I drove my first 80 miles (entirely city driving, with stop and go) after the maintainaces above (and a 33 psi tire adjustment). My milage now is ~15 (14.83 MPG to be exact). That is about a 34% improvment from the previous 11 or 12 I got with it. I will report on mostly highway driving later.
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