Thread: 1999 Grand Prix 3.1L Odd Problem.

I just purchased a 1999 grand prix SE with a 3.1L engine. the engine runs great however i was working under the hood and noticed the vaccum line running from the pcv valve to the intake then to a box( i think its the evap purge valve ) under the ignition coil was unplugged at the box . i plugged it back in and the engine died. leaving it plugged in and restarting the engine it would idle real rough and die if i didnt give it some gas for a min. unplugging the vacumm line again from the map sensor allwos the car to start and run fine. i am getting trouble code p0401 egr flow insufficient.

Originally Posted by Xware

I just purchased a 1999 grand prix SE with a 3.1L engine. the engine runs great however i was working under the hood and noticed the vaccum line running from the pcv valve to the intake then to a box( i think its the evap purge valve ) under the ignition coil was unplugged at the box . i plugged it back in and the engine died. leaving it plugged in and restarting the engine it would idle real rough and die if i didnt give it some gas for a min. unplugging the vacumm line again from the map sensor allwos the car to start and run fine. i am getting trouble code p0401 egr flow insufficient.

it sounds like your manifold is plugged with carbon where the egr valve hooks up to the manifold. you're going to have to take the egr valve off then you're going to have to take the snorkel off. then you're going to have to take your throttle body off. you'll see a passageway in the manifold that goes to your egr valve. that's probably where it's plugged up...

Originally Posted by Xware

do you think that would cause it to die when i plug that vaccum line back in? and run rough while its in? or are you just saying for the error code?

egr flow code pretty much tells you that it's plugged with carbon. it wouldn't be a bad idea to replace the egr valve as well. about $75.00. but you'll have to take off the throttle body to get a better look at it. my money's on it being plugged with carbon...

put in a new pcv valve as well. 3 bucks....