Intake or Exhaust?

[WackAssLife]

Check engine light comes on, I check with my OBD2 and get bank 2 O2 sensor. OK I got it, I need to change them, and preferrably all 4 at the same time. Question is, what is causing the sensors to go bad??? OXYGEN READINGS FROM MAF OR O2 SENSORS?

Also had my number 2 cylinder misfire until I took it out, turned over the motor maybe 2 or 3 revolutions, put it back in, and after that it worked fine with no more misfire. DOES ANY ONE HAVE A CLUE ABOUT A MYSTERY MISFIRE IN CYLINDER # 2. I KNOW CYL #2 IS THE LAST IN THE FIRING ORDER, THATS IT.??????????????!1111111!!!!!!!!!!!!!!!!!!!

 

[jlcvt]

When you say took it out, I’m presuming you’re talking about the spark plug. If the engine is fine then maybe:
1. Did the spark plug have a good connection
2. Is the spark plug in good shape
3. Maybe the plug wire is going bad

Not sure about the O2 sensors, but a poorly running engine will kill the sensors. The addition of the K&N filter and headers system can make the check engine light come. I’ve seen that happen before and then just have your computer tuned for your truck.

 

[WackAssLife]

Yeah I meant spark plug, it didnt look fouled, i heard the click when i removed it and reinstalled it so the connection was good, and i just replaced the wires about a month ago.. so i donno? it was definatley wierd. everything was fine until i pulled into a gas station to refill some fuel cans for yard work, and when I started the truck i noticed loos of power and a sputter. i knew I lost a cylinder, but didnt know why. Got home took the plug out, started the motor for about 2 seconds, then reinstalled it and it hasnt misfired since. so yeah that was wierd.

 

[WackAssLife]

after I knew I lost a cylinder I OBD2'd it to find out it was my #2 Cylinder. I've been having an issue with static when randomly touching body?? bad ground?

 

[chrish04]

If you can figure it out let Me know I have just random cylinder 3 misfire come on maybe just once or twice a month clear the code and it stays off for awhile

 

[hapyspaz]

You guys both probably need to test your fuel pressure. One of the most common repairs I do on Chevy vortecs is the fuel pressure regulator. It causes the check engine light to kick on, and codes are usually cylinder * misfire, multiple misfire, and multiple random misfire; as well as the codes that follow, like bank * running lean, etc...

 

[WackAssLife]

how do you check the fuel pressure?

 

[gary rabbitt]

"Check engine light comes on, I check with my OBD2 and get bank 2 O2 sensor. OK I got it, I need to change them, and preferrably all 4 at the same time."
Remember, just because you have an O2 code doesn't mean the sensor is bad. (Or for any other sensor you get a code for) You should check other things as suggested, before replacing something that you might not need. ($$)

With all the diagnoistics nowadays, some armchair techs get too far into the woods and start changing sensors, etc. unnecessarily.
What needs to be done after the codes reading, is to check the basics. Air, fuel and spark. The fuel pressure check is one of the basic things, if your fuel pressure is low, or unregulated, it can show up as all kinds of symptoms.

"Got home took the plug out, started the motor for about 2 seconds, then reinstalled it and it hasn't misfired since. so yeah that was wierd."
When you "started" the engine, I assume you mean cranked over and not actually fired up?
My first guess is that one of your wires had been barely hanging on and positioned close enough to fire until your trip to the gas station. Reinstalling , you might now have positive connection, hence no misfire .

Good luck, Gary.

 

[WackAssLife]

thanks gary.. is there a way to check the fuel pressure? what would cause "low" fuel pressure?

 

[gary rabbitt]

Hi,
Generally, you can test the fuel pressure at the fuel rail, there is a Schrader valve (same method of valve as your tire stems), connect the pressure gauge there.
The regulator can be at fault also, the fuel pump itself. Have you changed your fuel filter?

Rather than to paraphrase the info I have bookmarked, have a look here for a longer explanation of the prressure issue.

http://www.automotivehelper.com/topic660201.htm

Good luck,
Gary.