Well all this started about two weekends ago when taking our daughter into Philly to the Wells Fargo Center to see the circus....
Stopped at a red light and while waiting I could feel an erratic idle/misfire. I could feel it through the seat base actually. I didn't say anything and as soon as we took off, just moved off idle, it smoothed out and went away. Next red light, same thing. The wife noticed it this time and asked what was up. I, of course, declined any info (haha), and said "ugh, its nothing, just a weird misfire".
Well after alittle bit of highway driving it went away and didn't happen again til' later that night on the drive home. It was loading up bad at idle at stop signs/red lights and you could smell the exhaust strong, even in the car.
I checked the codes the next morning using my Actron Scanner and it pulled up P0171.... System too lean (Bank 1). I cleared the codes, she drove it, and it was fine for a day or two. Then it happened again a few days later while she was driving home from work. I checked again, P0171, and now P0131.. O2 Sensor Circuit Low Volts (Bank 1, Sensor 1). Cleared codes and it was fine for a couple days.
Now tonight, it did it again on her way home. Checked codes, P0131, P0171, and now, P0300.. Random/Multiple Cylinder Misfire Detected.
So I had to clean the CAI anyway, so I've got the filter drying now and cleaned all the tubes/connections/etc. Had to be done anyway, regardless of all these codes.
Now, after checking/searching on here, I've come to the conclusion I'm gonna have to check the driverside, front O2 sensor.
I'll check it tomorrow afternoon once its cooled down some..... We'll see?!?
I got mine replaced today... so we'll see! So far, so good..... I've gotta run some errands tonight so I'll drive the Yukon and see if anything happens.
I ended up getting a new Bosch 02 Sensor at the local Carquest... $44. Not too bad IMO.... that is if it fixes it!
Mine was a bitch to get out... it was super tight and it ended up pulling the threads off the old 02 sensor and leaving half of them in the 02 bung... I had to use an 02 sensor bung tap to clean up the threads in the bung and then I got the new sensor in.
Changed the sensor, rotated the tires, ck'd the brakes, changed the oil/filter, cleaned the CAI, and oh yeah, dropped the front alittle more
OK, I have changed the drivers side O2 sensor and so far so good. After clearing the codes I took her for a spin. The idle is back to normal as well as my fuel consumption.
OK, so after a few more miles my truck was up to its old tricks, same codes along with the rough idle. I thought maybe the O2 sensor I had replaced was defective (the box said they were very fragile and if dropped not to install, I figured that was the problem) so I replaced it under warranty. Same thing with the second sensor.
I decided to then clean the MAF with Revive sensor safe spray... it seemed like that had solved the problem - until a few miles later, same thing.
Again I looked for vacuum leaks using an unlit propane torch to no avail.
As a last ditch effort before I took my truck into the shop, I ran 1/3 of a can of sea foam though the brake booster vacuum line and then poured the rest into my fuel tank. I figured maybe one of the injectors was gummed up. Well it has been 70 miles since the seafoam and the CEL has only come on once after a rough idle at a stop sign -it cleared its self shortly thereafter.
I also took it on the highway for a sprited drive to work some of the sea foam in the fuel through the engine. On the return leg, with no wind I saw some of the best mileage I have ever seen. At 60 mph, with no wind and only minor elevation changes I averaged 19 mpg. The idle has smoothed out and no check engine light since. Looks like I changed the o2 sensor for no reason.
Next time if I suspect a faulty O2 sensor I'll switch it to the other side and see if the codes change.