O2 sensor/mpg

marek

Registered User
Hello

How much more gas when O2 sensors are bad?,and is it possible they are don`t work correct but test KOE,KOER "said" OK.

I have very bad gas mileage 12-13 in city.I cleaned MAF (it wasn`t dirty),changed filters,spark plugs .
I don`t know what else I must check.
Ps. my foot isn`t heavy.
 
I am also having a similiar problem with poor gas mileage. I get about 180-200 miles per tank. Thats about 50/50 interms of city and highway miles. I brought it tp a shop and they told me its the o2 sensors. Is your car idling rough after sitting for a while or stalling at all? Weirdest thing of all though. I just took a trip up to Albany, I was getting about 330 miles to a tank doing 75-85mph the entire trip.
 
I actually haven't gotten a chance to check anything, but a lot of the guys here say that the o2 sensor code comes up a lot as a phantom code, they been aiming me towards my IAC
 
Hate to say it guys...

Yeah, it sucks to spend the money, but...if your gas mileage is bad, it's pobably those sensors. Mine was sitting at about 13-14 mpg and it ran perfect, idled fine. When I changed them out (completely simple job by the way, took 20 minutes) mileage went up to about 22 mpg (mostly freeway driving). If your car is idling rough, it could be that you've shot so much gas (unused) out the exhaust and half-plugged a cat, and the increased backpressure is creating problems. Maybe not, but could be. O2 sensors, if they haven't been done in a while though, are probably the culprit - change them!
 
I replaced a faulty O2 sensor two months ago. I was getting around 20 mpg with mainly highway driving. Now I am getting between 24 and 27 mpg on average. It was also one of the few repairs I dared do myself!

Brandon

1994 5-speed
 
I bought my Bosch sensors from NAPA. They were under $90.

I also have the longer leads for headers.

Make sure you get the right ones. I did not (bought the 4 wire sensors per the SC parts list for Kooks headers by mistake. I have a 90 SC and should have 3 wire sensors ) I did not notice and had poor gas mileage and Ce light. Course with doing a few mods at the same time I knew it could not be the sensors.....

Till I changed a number of other things I finally decided to change them out. Found out my mistake. Runs good now though
 
I got mine from napa

They were 130, and obviously worked...but I've read that some ppl got some from Autozone or another place for about 70...so it can be done fairly cheap. Don't know how well those kind work though...just make sure it comes with some kind of anti-seize for the threads...
 
I bought mine at autozone. They were Bosch and they cost 82 bucks a piece including tax.

Brandon

1994 5 speed
 
For the 1990 Bosch
BSA 13942 NAPA online for 39.99

For the 1995

BSA 13127 NAPA online for 70.99



My car is a 1990
 
Do the 89-93s have 2 02s in the same place as the 94-95s? How come they are so much more? Are those prices for both or just the second one? Has anyone ever replaced the downstream 02 and it make a difference (alone)? I opted to replace just the upstream one because of the price.
 
O2 sensors

the oxygen sensors are a maintanance Item so if it's been more than about 60K miles OR if you have ever blown a head gasket i'd change them (coolant will damage them)

If you go to NAPA and buy Bosch O2 sensors before the end of December you can get a $10.00 rebate PER SENSOR from Bosch by mail....... at least it's one rebate deal that is worth the price of the stamp!.
 
I just replaced O2's tonite on my mom's 1993 Thunderbird 3.8L NA after completing a HG job. WOW, what a difference that made. I knew the one was toast from coolant, but I still didn't expect it would make such a difference. Car idles great, runs good, and definietely has more pickup! I'll be replace the O2's on my SC and my MK8 real soon, as I have no idea when they were last replaced. I got the Bosch sensors from Advance Auto for $45 each.

Thomas
 
On my stock 89 XR7 the driver side 02 sensor is smaller than the passenger side, Is there a different part number for the part when i get new ones or can i replace them both with the same one?? Thanks


NICK
 
Where are they?

Hey, that sounds like the same problem I'm having with my 1991. It runs good, but fuel economy is way down. Where exactly are those sensors?
 
hey XR7 they should both be the same, Bosch part number for 89 and 90 is 13942. Maybe somebody already replaced one and it's just a different brand and looks different.

Rrlcommish the Oxygen sensors are in the exhaust, the left on is in the manifold itself and the right side is in the pipe just below the manifold.
 
unplug the wires and unscrew them. that simple. you might spray some penetrating oil around the threads a little while before you remove them just in case...the new ones will have antiseize on the threads.
 
O2's are easy to change out. They run about $80 for the set of two. Definately use Anti-Seize on new ones. As far as the IAC valve that was mentioned earlier, you get the "dying goose honk" upon shutoff, weird sounds coming through the K&N in cool air (usually in the morning), and in worse case scenario..you get about 1 gallon to the mile with a really strong fuel smell out the tailpipes.:D This is because the IAC lets in too much air when bad, and the comp tries to compensate by richening up the A/F mixture, thus the "Phantom O2 Code" and poor mileage. The IAC is also about $80.

My bad IAC ended up the prob and phantom O2 codes were showing when running codes, and the new O2's didn't help. If no goose honk, then go for the O2 Sensors as they need to be replaced every (50,000 miles?) so many years anyway.
 
Back
Top