I have two problems currently with my truck that I need some help with. First off, every often like once every 1 oe 2 weeks my trucks CEL pops on and it starts to run really really rich. I mean so rich it smells like its just dumping gas out of the exhaust. Like straight gas. Just smells like it is not literally. It causes the truck to run a bit odd. It just sorda has a small miss at idle and every once in awhile when Im driving it , I will feel a small miss. But anyway, the missing out and the smell goes away along with the CEL, and everything back to normal. Last about a day. I figured it was the 02 sensor but wasnt sure if because it keep correcting itself then messing up again.

My second problem is my air switches up to defrost under moderate acceleration and I was told that it was the PCV check valve or something like that. What and where is this located, also could it be anything else.

Any help would be greatly appreciated.

 

what is the code for the CEL? and no the PCV is not for your vac supply to your AC. There is a check valve inline to your vac line that goes into your dash from the outside usualy next to the AC lines that go into your dash froim the firewall. Now this might be a ling shot but if u have a code for fuel system rich and the ac goes to deforst at the same time then u have a vac leak some where. I know then intakes leak sucking in oil or coolant. The check valve is near the intake manafold in some way. Also connected to your Speed control vac lines.

 

I dont know how to check the codes or anything. But Im not sure that its sucking in oil or coolant because the air has always switched to defrost under moderate acceleration since the day I got the truck which was like a year ago or so. Its been only acting up like this for about half a month now. Ohh also if it makes a difference, the A/C doesnt necessarily have to be on . It still does it if its just the fan.

So how do you read the code(s)?

 

just so you know the pcv is located on the left cam cover its a little valve that looks like a crack pipe and it is a form of exhaust gas reburn it sucks unburned gas out of you motor and re-introduces it through the intake. its full name is positive crankcase ventilation, PCV
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Your second problem is a vacuum leak, i had the same problem you have, i checked all the lines and found one that had fell off a "T" connection. Hook a vacuum gage to your manifold (my favorite spot is the brake vacuum booster line)and check the reading. Fluctuating needle = leak.

99 5.9 magnum sport quad 4x4