Check Engine Light

[T_Aggie03]

Alright, I have '93 Explorer XLT. Everytime I get on the highway, after about an hour to two hours of driving, the check engine light will come on. Along with the check engine light, the RPMs will go from 2400 to about 2800 and back down to 2400. It goes back and forth for a while, sometimes it quits sometimes it doesn't. Keep in mind that the light only comes on on the highway. In the city, however, I have rough idling, and surging when accelerating. Any suggestions, I was thinking maybe the FPR or O2 sensor. I don't really know much at all about this stuff (Sensors) so I am relying on all of you.

 

[racinjason68]

Well I have had the same prob w/ my 91 only it dont surge it just stays tach'd @ about 3200. If I shut it off and restart it, it finally quits. I wish I knew what the deal is.

 

[jemail]

I get this same surging problem every month or two and have CAREFULLY taken my MAF sensor out and sprayed the 2 probes with Carburetor Cleaner ( make sure it says on the can that it is O2 sensor safe ).

I am not sure if this is what actually solves the problem, but it does seem to be a quick, inexpensive fix that I learned off of other's posts.

 

[white94]

The Throttle Position Sensor will cause the surging. Also, causes rich/lean situations and fouls O2s after a while.

Try that.

 

[Triton46]

91 - 93 is infamous for the FPR (fuel pressure regulator) and O2 sensor. The FPR goes bad and causes the engine to run rich which can ruin the O2 and set off the Check Engine.

 

[white94]

I have a check engine light after 1 to 2 hours of driving on my 1994 XLT, but I get no surge. I changed the TPS, and life was great for a couple of trips, but now it is back to the same. I also cleaned the MAF, but it looked great when I took it out. After an hour or so, I get check engine intermittently and lose power on hills. My code scanner gets stored codes of Rich/Lean on both sides. No codes while engine running.

I was wondering if I should just change the O2s or if I should be concerned about something upstream causing the problem. I hooked up a fuel pressure tester and drove it around for a couple of days hooked up and monitored the pressure. I saw no signs of a FPR problem. Any ideas? Should I just suck it up and change the O2s? I have 130,000 and I don't know how old they are. I just got it at 125,000.

Thanks all - in advance.

 

[jimbo74]

ok....this is for everyone...i have the same thing... YOU NEED TO CHANGE YOUR O2 SENSOR

i had the same thiing with the light and the surging... i went back to my ole high school and ran codes with my shop teacher: Exhuast gas oxygen sensor lean condition & Exhuast gas oxygen sensor rich condition....
THIS MEANS IT IS THE O2 SENSOR

 

[white94]

All right. I changed the O2 sensors, the plugs, wires and, while I was down there, the Radius Arm Bushings. Last weekend went on a road trip. Better mileage and no lights. Good performance on the hills. Looks like that was the trick.