Hi, this is my first post here so greetings! I'm also a member over at DSM, and love car forums like these - best
places in the world to meet great people and share info on the cars we love.
Anyway, my 21 year old son has a Pontiac Grand Prix (GT I think?) with the 3800 series motor. Its not supercharged.
He's been trying to fix it up and I've been trying to help him, Car has 182k + miles on it.
In the last 2 days, we installed new upper (phenum?) and lower intake manifold gaskets, as well as valve cover gaskets.
It all seemed to go pretty well, everything seemed to go back together good and we didn't break anything that we are
However, on the backside of the engine compartment, between the firewall and motor, right next to the alternator, and
coming off the same place in the harness where the alternator plug and hot wire comes from, is a 2 prong blue colored
connection. For the life of us, we can't remember where it goes, or if it was just hanging free there. So any info about
this plug and what it it/where it goes would be much appreciated.
My son took some pictures of this with his cell phone. As soon as he e-mails me the pics I'll post them here, if that is
Now to the real problem. After we put everything back together, including changing the oil, filter and antifreeze, the
car cranked, but would not start. We checked the fuel rail and it had pressure on it and gas spurted out. We also
checked for fire at the coil packs and everything was sparking there.
We went back, plugged and unplugged the connections one by one. Finally, the car started back up. However, it is
not running right. It starts up at close to 1.5 to 2000 rpm and then gradually goes up close to 3000 rpm. Driving it
down the road like this is rough, it acts like it won't shift out of 2nd gear and is revving very high.
Oh, and sometimes it goes back and acts like it did when we first got done, it won't start at all. We fiddle with
the plugin connectors and it'll start back again.
It "feels" like something vacuum related to me but after we went back over the motor again, we couldn't find anything
else (besides that one plug) loose.
Can anyone give us some ideas as to where to start to try to figure out what is going on? keep in mind, the car was
not doing any of this before we installed the new gaskets.
Thanks, any help is greatly appreciated!