ive been reading all the posts i could find on 1406..egr pintle valve....the car has a jerk, shudder , almost feels like when your in a headwind and your overdrive wants to downshift upshift ect, this was only slightly noticeable at very low no load situations, steady ten mph for example, under accerleration it was fine, now even at speeds of 65 downhill or light load it starts this shuddering .....has new plugs wires...also had the 300 code random misfire, cleared it and the 1406 came back....94 bonnevile 3.8 engine is from a buick lesabre, i have the egr off looks clean, it has a rattle sorta like a pcv valve when you shake it...really dont wanna spend 150 at rock auto only to still have this problem, always starts, never dies out.......i better quit rambling fustration has set in....thanks

I looked briefly and didn't find it right off, if memory serves me properly the 1406 is an error where the pcm sees flow when no flow is desired. If that'* the case, then the flow is detected by the map sensor and the EGR is not the issue.

Look further into it though. I'm going off memory and might have a code close to yours on the brain and not the exact code.

how would i check map sensor, and where is it

ok thanks to rock auto i found where its located but,,,,how in the world a dummy like me gunna test that? im already thinking junkyard lol

i forgot to add before when i shut the car off i can hear a vacum leak right at the cruise control, is this normal on a bonny? read so many replies concerning vacum leaks but ive sprayed either all around while car idles and nothing changes, just thought id throw that in

Please fix the obvious items. and you are correct, vacuum leaks are not normal.

im going to the junkyard today for a different egr valve and map sensor. ill see if that changes anything.

If I am right on what I remember, then the map sensor is reading the excess air being allowed into the system and figures it must be the EGR because it'* commanding the EGR to do something different.

Might not be map or EGR with the lastest info you supplied about bad vacuum lines.

Suggesting you fix up the bad lines and see if the issue still exists.

i went to the local junkyard bought two egr valves ..tried them nothing had changed, couldnt find a vacuum leak, so i headed to the dealer , and whadda know they said you got a bad egr valve, so i bought the bullet and headed to oreillys , and yes the car runs great, i guess being outside in the elements isnt the best thing for those egr valves...oh well the bonny is happy again, thanks for all the help.