I have a V6 3.1lt, i have spark, fuel pressure and air but when i go to start it, it just bucks then dies. what could be the problem?

 

Please clarify. What do you mean by "bucks". Do you mean it starts and stalls? Does crank but wont run?("crank" is the act of turning over with the starter) Does it backfire or "pop" from the exhaust or intake when you attempt to start it?

 

When I try to start it, yes its more of a backfire out the exhaust. it idles under 500rpm for like 10 seconds then dies.

 

Double check plug wire routing and firing order. Check spark on all plug wires. Has any work been done to it recently? Could timing be off?

 

I checked the firing order multiple times. Yes it just came out of the shop because it wouldn't pass smog. They changed the egr valve and changed the oxegen censor. When i got it back it was idling funny, like when i brake the rpm goes down to 500rpm and sounds like it wants to die but doesn't. Also when i replaced the spark plugs they were covered in oil, that cant be good right?

 

One more thing to add, it ran fine besides the idling problem. All i did was replace the spark plugs and the wires are in the correct firing order.

 

The EGR valve may be stuck open. That would explain the poor idle and the firing out the exhaust. Have you had it back to the shop where the work was done? If this happened to a car I had just worked on, Id want to know about it. A piece of carbon may have gotten stuck in the EGR valve.

You say the plugs looked oily, does the engine smoke? How is the PCV valve and tubing? Is it all in place and sealed? Did the shop perform an injector cleaning on the car? That can leave some pretty scary deposits on the plugs. If you can reach the EGR valve with your fingers, try lifting and releasing the diaphram with your fingers. This may dislodge any debri thats causing it to stick open.