I've been reading the forums for a long time now and there is some really valuable information here. This is my first post and I'm hoping we can figure this out it is becoming very frustrating.

Last week i did the plenum repair becuase the truck was eating oil and i was getting misfires. Did the repair reset the computer and took the truck for a drive. the check engine light eventually came on not long into the drive and the code it put out was a misfire in cylinder 8. Thinking that maybe the plugs were fouled i replaced all the plugs with some NGK V-Powers. Ran the truck again and yet again the light came on for a cylinder 8 misfire. I attached two pictures.

Cylinder 8 Plug



Cylinder 2 Plug



These two plugs are only a day old and have around 50 miles or so on them.

What can be the issue i really need to get this fixed so i cant pass inspection.

 

if you'll look in the DIY part there is a bulletin about how to run the wires, did you follow those procedures?

 

Also, did you do anything with your cat? O2 sensors??

Pics aren't showing??

 

I ran the wires per the TSB bulletin found in the DIY section. Also i did not doing anything with the CAT or O2 sensor. the cat was replaced 3 years ago because it had failed. The O2 sensor has not been replaced since about 5 years ago.

 

Take the pre-cat O2 sensor out, drive the truck, see if your code comes back. Three years of burning oil from a blown plenum will smoke the cat. (and that's probably what happened to the first one.....)

If the code comes back, (or, even before trying the above test...) check the connector on the injector. If they are a bit loose, that can also cause a miss.

 

Alright i think i fixed the picture issue. they should show now (I Hope).

ill check the connector and pull the pre cat O2 sensor. When i pull the pre cat O2 sensor that should send a no O2 sensor code correct?

 

Yeah, it WILL set a code. We are more interested in if it runs any better though. It's an easy test for a clogging cat.

Plugs don't look bad, top one is a tad sooty? You get a puff of blue at startup by any chance?

 

Nope no smoke at startup at all. the truck idles around 500 RPM which i think is a little low but the needle does not jump at all.

Like I said the plugs are brand new only like 50 miles on them. the 8 plug seemed pretty sooty pretty quick.

 

Comp test time, or did you do one already before you did the plenum gasket, if so numbers please.

 

Ok so i unplugged the connector to the pre cat O2 sensor and drove the truck a good time. all i did was unplug the plug that was on the sensor. i didnt actually take the O2 sensor out (thats Ok right or does it need to come out and stay connected.

Well anyway i drove the truck with the sensor unplugged and it seem to run about the same. it threw two codes the P0132 code for the O2 sensor and the P0308 code again for the misfire in cylinder 8.