Thread: dtc code p0440

Hello everyone new to the site. Having problems with my 1999 grand prix se. about a week ago my car started flooding the motor with gas and the check engine light came on reading p0440 evap performance problem.I'll start the car in the morning and drive for about 10 minutes just fine then it will start flooding the motor, I can put it in neutral and shut the car off and restart the car and everything will be fine once again for about another 10 minutes and the problem will start all over again. I've cleaned the egr valve which seemed to be the problem from all the carbon build-up but was not, check the evap canister, its fine purge valve fine, vaccum line from in-take to pressure reg fine return lines fine. everything seems to be fine.I know a pretty good deal about cars but cant figure out what if anything the problem is. The only other thing I can think of is the pcm and its hard to believe that its bad. any help would be great thanks

I dont have a fax number

thats alldata flow chart for a 440

thanks yall. I went step by step and found nothing wrong did notice gas vapers in the intake so I might get new pressure reg or trade in the 99 grand prix se for the 2000 gtp coupe I found last night. Have to wait til dealership opens monday and see if I can make them drop the price alot. They asking $8000 with 110k on it. who know what we happen I might just take it at that price, been wanting one for along time!!!

hey more problems have more codes coming and going p0341 p0327 p1860. I know what all of they are just dont understand why they are coming up and going away and I;m not finding anything wrong like the knock sensor i just went and replaced it and the code came back no wiring problem on it or cam sensor any ideas

hey the first code of 0440 started having the other come on i would read the code but not delete it or be driving and the check engine light would come back on the few minutes later would turn off

oh did look at the coil packs the other day and found one that had alot of rust on it cleaned it up and replaced the wires and going to get the last three spark plugs and replace them today