Which Sensor Do I replace?

[JayTye4k]

I am getting horrible gas milage and awful driveablitity out of my 1995 XLT (Rough Idle, hesitation, etc.) I have come to the conclusion that my Oxygen Sensor needs to be replaced. I've heard that some explorers have 2 oxygen sensors and others have 4. Upstream and Downstream sensors. Does anyone know if the 95 has 2 or 4? Also, how do I know which sensor is bad?

Thanks!


Jay

 

[glfredrick]

I would start by runing the computer codes. They will store data on the oxygen sensors.

 

[JayTye4k]

I don't have a code reader...If I have to take it up to the shop, I might as well let them do it all..Trying desperately to avoid paying for that. I am not getting a check engine light at all...

Also, I am thinking about paying (Too grueling) to have my upper intake manifold gasket replaced. Could this cause the rough idle that I have? What should I pay to have this done?

Already replaced IAC, MAF, fuel filter, plugs, wires.

 

[glfredrick]

Autozone will read them for free...

If you are worried about the cost of taking it to a shop, and don't want to read the codes, just replace all of the oxygen sensors. If you have some mileage on them, they are probably due in any case.

Also check out the air filter.

Do a search for "aldive" and read up what he did to increase mileage.

 

[95expledbau]

'95 has 2 oxygen sensors $59.99 autozone, $48 JC Whitney. To determine which one is bad you must pull codes. Invest $35 in a ODB-I code reader instead spending a small fortune on random parts (MAF, IAC) Spray carb cleaner around the intake manifold while engine running to determine a vacuum leak. It could also be faulty EGR system. I could go on and on and on...

 

[MrShorty]

Most all '95's are EEC-IV, which means the only "tool" you need to pull the codes is a paper clip. Try reading "getting codes" at www.fordfuelinjection.com Some prefer to use a code reader; they say it's easier. I've always just used a jumper wire.
As for the upper intake gasket, is it leaking? Any kind of vacuum leak can cause driveability problems as well as lean O2 sensor codes. If you know of a vacuum leak, I'd fix that before worrying about replacing the O2 sensors (a '95 should have 2 O2 sensors I believe).
I just reviewed that web-site. I'm not sure they have the description for hooking up the STI right. I know the diagrams at www.dalidesign.com/hbook/eectest.html are right, but they have you hook up a voltmeter or test light to read the codes. You can just jumper the STI to STO and read the codes out as flashes of the check engine light.

 

[newbi]

Do the codes as suggested (IMHO) that'll get you on the right track. I've always heard the MAF meter controls the fuel flow and the O2 sensor only fine tunes it.

 

[JayTye4k]

You guys are awesome-Thank you so much for your help!

 

[stubborn1]

Since you mentioned that you aren't getting a check engine light, a code scanner by itself won't tell you which O2 sensor is bad. The best bet would be getting a scanner that can measure the voltages at each sensor and then compare against recommended voltage readings.


I hate to say it, but your best bet is probably taking to a mechanic for a diagonostic instead of throwing expense electrical components at it.