For as long as I owned my truck, I had a rough idle that would almost make the truck die while waiting at stop lights. It would normally occur when the truck was thoroughly warmed up, and I would come to a stop, say...at the bottom of a highway off-ramp. It would never die, but it would idle like crap, and then all at once snap out of it. Sometimes if the light turned green before the truck would come to, it would take off with like half power, before snapping out of it.

I took a small repair shop owner for a test ride, and made him ride with me until it acted up. He then, knowing how to reproduce the malfunction took it out with a diagnostic computer attached. He found out that my upstream passenger-side O2 sensor was completely kaput. He hypothisized that it's demise was because it gets subjected to high levels of heat. He replaced it for me, and I have had a perfect running truck for three weeks now.

BTW - My last two fill-ups have revealed an average 20.1 MPG. Yeah, I drive mostly suburban Illinois highway miles, but I had been getting 17-18!

P.S. The fix-it shop was Gorecki's Auto Service in Geneva, IL.

 

I have a 97 XLT F150 4.2L.

I noticed the same problems you were having. I ask Pepboys my local autoparts store about it and the guy said to repalce the oxygen sensor. But he said their are 2 of them in their.

Di you know how many are in their and whihc one should be replace first if their 2.

Thanks

 

Man that sounds exactly like what mine is doing, I'm going to have that checked out, I'm also getting horrible gas mileage, I bet the two are related. Is there any way to visually inspect the sensor to see, like does it look burnt or anything?

 

man you just struck gold ive had that same problem since i bought my truck 2 yrs ago ill be at the autoparts store tomorrow. cool..

 

Hey, thanks a ton! I've had this same problem for about 2 years now exactly as you described. I'll have new oxygen sensors asap. Thanks again!

 

The O2 sensor is the upstream passenger side sensor. There are a total of four on our trucks, two on each side. The old sensor had no distiguishing wear or burns, but it sure didn't work. In order to fix the problem, you have to replace the correct one; with a diagnostic computer, you can pinpoint which one is not working.

update: two more fillups with 19.5 and 20.3 mpg. Now that is why I bought the V-6.

 

I think this thread is the greatest thing to ever happen to my V6. I cannot wait to get those 02 sensors checked out. I have been dying at stoplights for a year and a half, and not one shop I took it to really took the time to figure it out. Thanks man,

Crotteau

 

You really getting 17 to 20 mpg? I fill lucky if I see
16 out on the hwy, in town getting about 14.5 mpg.
Have you done any thing to the motor?

 

Tucker, I'm in Texas also, Fort Worth. I get 16 City and 18 -19 highway. Only modifications are the airbox mod and dual exhausts. I have the auto with 3:55 rear.

 

Tucker,

Only mods are a Gibson 3" catback (very highly recommended), and a K&N filter (honestly can't tell a difference). I just try not to race away from stoplights, and don't go over 75. When on the highway, I hear it is better to run the A/C than to open the windows. I guess the compressor does less damage than all that drag.

 

Hey guys, I replaced both of my upstream (or front as NAPA called them) 02 sensors. My truck now runs fine. One of the sensors was a Bosch and the other had an unknown brand on it, so I assume they were replace before. This bothers me as I only have 55000 miles and I bought the truck with 16000 miles on it. Well, see you guys later. Thanks again for the fix to this crazy problem.

Crotteau

 

I finally got around to replacing both upstream O2 sensors and my intermittent rough idle problem is completely solved. I finally got a P0153 code and put the new sensors on. My 153k mile truck runs almost like new and I only regret not doing it sooner. Thanks for the help.