loss of power-o2 sensor?

[pwayne]

My wife's 2005 explorer has 125,000 miles on a 4.0. It has hardly any power, will barely pull it's own weight and mileage has dropped to about 5 mpg. This problem happened suddenly, as in, it was fine driving from work one day, she stopped at her mom's house for a bit and when she got in it to come home the problem had developed. About a year ago a similiar problem was fixed by having an o2 sensor replaced. Now though, we are broke and can't afford to put it in a shop. I could replace the sensor myself if I knew whch one it was (there are 4)and if that was for sure the problem. We live too far from an autozone to get a free diagnostic so i ordered a cheap obd-ll code reader from amazon but it won't work on the ford although it works fine on my cousins chevy. I have checked all the fuses and replaced the fuel filter. Today I unhooked all 4 o2 sensors thinking this might tell me something but it seemed to make no dfference in how it ran at all. What conclusion might i draw from that fact? I really need to get this fixed to go to work monday. Really appreciate any help you can give..

 

[LONO100]

did you get a CEL ? when the engine is going, but its in park, how is it revving?

 

[ncranchero]

First, it will not rev over 3000 in park or neutral because its limited to that when not in gear.

CEL light?

Fuel filter changed ...... ever?

Check all fuses, an OBD-II scanner should read yours if it reads a chevy.

 

[pwayne]

thanks for the responses. I didn't know that about the limit on the rev when in park. How about in neutral? will check all fuses again. unknown about the fuel filter, will check that too. I was gone for a couple of years until recently so don't know as much history on the vehicle as you might expect...

 

[ncranchero]

Revs are limited to 2800-3000 in Park and Neutral.

 

[pwayne]

good to know...

Cool, thanks. Guess I'll try a drive around the block while the sensors are unhooked and see what it does. Oh, and meant to mention originally that the gas mileage had dropped to 4.5 mpg.

 

[pwayne]

now what?

checked all fuses and replaced fuel filter. no change. this really acts like a Ranger I had a few years ago did when the catalytic converter was clogged, except that was more gradual and this happened so suddenly. Shouldn't it have acted different somehow with the o2 sensors unplugged? Or no?

 

[waskly]

checked all fuses and replaced fuel filter. no change. this really acts like a Ranger I had a few years ago did when the catalytic converter was clogged, except that was more gradual and this happened so suddenly. Shouldn't it have acted different somehow with the o2 sensors unplugged? Or no?

o2 just read trims, you have lose of fuel pressure or clogged cats.

 

[LONO100]

i was referring to if the rpm's were jumping up and down when you had the motor running and in park. when i had a bad vacum leak, i had similar symptoms as yours, and when i would turn the truck on, it had weak and jumpy rpms at idle. i also had the CEL go off. once i fixed the leak, all the problems stopped and i got my power back.

 

[pwayne]

re:jumpy rpm's

Thanks for the input; I can't hear any obvious vacuum leaks, where was yours located? Is there a ghetto/cheap way to find a leak?

 

[pwayne]

and yes the check engine light is on

 

[LONO100]

yeah, look up the p0171 p0174 sticky. i had a bad tear on that rubber tube. cost me exactly 1 dollar to fix. aamco wanted to charge me 600 to start when i had them read the codes for me. if that isnt it might be the upper intake manifold. get the cel read if you can. good luck.

 

[pwayne]

Problem solved. . I took my last 60 bucks and bought a universal Ford O2 sensor and started switching them out. The second one I tried, the one on the driver's side in front of the catalytic converter did the trick. Thanks to all for your help.