Plug wires look new, no idea on plugs I'll pull one tomorrow night. Not really noticing any rough running.

Quick search has me guessing upstream O2 or a coil pack since they are on the same coil.

Not sure if this is related but the cold has really hit our area. I have noticed that I must have a air pocket in the heater core. The heat isn't as hot as it should be, and at idle at stop lights I the air cools off. Watching the temp on my phone. I'm between 194 and 197 depending on what I'm doing.

Thoughts gentlemen and ladies?

Other than the codes popping up twice she did great on the 900 mile round trip to Ohio and back.

 

Do you have SAI? I was getting misfires in #4 & #6. Ended up being a vacuum leak in the hose that connects to the steel pipe from the SAI.

 

I do have sai and had gotten codes for it in the past but it has reared it's ugly head for awhile.

I'm getting pretty solid vacuum according to the torque app around 23" or so at cruise/idle. I'll look around for leaks tomorrow when I pull a few plugs. I can get in the garage tomorrow night while my wife is out with my daughter at gymnastics.

Thanks for the idea Mike

 

I'd say a vacuum leak is a good possibility. Mine had similar misfire codes until I found and repaired a leak where the brake booster connects to the plenum at that stupid o-ring/collet connection. I used plumbers epoxy (had it lying around) to fit a vacuum coupling in the fitting after breaking it while trying to find an o-ring that fit. No more leaks and no more codes. It makes sense that it would be worse in the cold when everything has contracted and the leaks open up more.

Regarding the heat, if you don't hear a waterfall you don't have air. I'll bet it's a blocked up heater core. Just disconnect the heater hoses and backflush it with a water hose. the bottom line, the one that connects to the water pump, is the one you need to force the water through. Mine was the same way when I bought it and that's all it was. Lots of crap came out. After I flushed it with a hose I blew out the water with a shop vac running backwards, then poured some distilled water through it then filled it back up with coolant. You will end up with lots of air in it afterwards so be prepared to run the truck on the highway for a while afterwards to get rid of the waterfall sound.

 

x2 on cold helping to bring the vac leak to the main stage. gotta hate shrinkage.

 

I was in the pool!!!

 

hahaha. that was a good one. second only to the "master of my own domain"

 

Well I searched for vacuum leaks but noticed since it has warmed up to the 20's I haven't had an issue. Plugs looked fine, no strange deposits gap was correct electrode not to worn.

For right now it's behaving and it's cold so I'm going to pray the rover gods just don't like sub zero temps.