I have a 1994 3 0 5 spd 4x4. I have read and read and racked my brain on an issue. Recently truck showed a light smoke. Not sweet smelling nor losing coolant but before diving into head gaskets I want to make sure I have covered everything. i have tried the vaccum test on the egr valve and it doesnt kill the idle. Could this not closing cause issue for the smoke. Oil is not milky nor losing it. The exhaust smoke smells like fuel. Any help is greatly appreciated. Ive read 40 million diff. Options

 

If you're not losing coolant, it's not likely a head gasket issue.

 

What I am thinking but what to check? Could the egr valve staying open cause the smoke? I am going to pull and check the plugs tom.

 

If the EGR valve is open, and not clogged, the engine would idle very poorly, or not at all.
Smoke that smells of fuel would suggest a fuel management issue.

 

Just to state the obvious, all gasoline powered vehicles produce "light smoke" when started on a cold day. Perfect combustion leads to water and CO2. When the exhaust system is dead-cold the water vapor is cool enough that it turns to mist when it hits the cold air. Once the exhaust system warms up the water vapor is hot enough that it dissipates before it can condense to mist.

Assuming you're still seeing smoke after warm-up, put your hand in the exhaust. "Wet" is coolant, "oily" is oil.

I agree with Millball that it's unlikely that your EGR valve is leading to smoke. Your NOx will go through the roof and poison all of us, but you can't see it.

Do you have a "miss" at idle? If a cylinder isn't firing, all that unburned fuel is dumped and will be visible as smoke. (Though, at that point, you should get a CEL.)

 

I recently had a code 71 thrown. It was not visible smoke warm then but now it can run warm and still smoke. I will check exhaust today but I was going to pull the plugs and check them.