gt 3.8 run's rough on idle

[rjinmt]

2001 pont grand prix gt 3.8 it runs rough until you unplug vacuum hose and then it will straighten out, of course it also picks up on idle

[GTP Dad]

Which vacuum hose are you unplugging? I would check and replace the PCV valve if you haven't done so in the past several months, it could be sticking and not allowing air into the engine.

[rjinmt]

there is a hose right by the front of the throttle body inlet that is the one I was unplugging , plus when I got to looking the upper plenum was leaking so I am replacing that ...if it will ever quit raining!!! I don't remember when the pvc valve was replaced , but I have to replace it any ways since I was dumb and snapped the sensor when I tried to take it off...but ya I didn't think of that...I know start with the simple stuff first ..will try, thanks.

[olopezm]

By the throttle body? I think you mean the one that has a 'T' with a small nylon hose and a thicker one.

If that's the case I would inspect the Fuel Pressure Regulator at the end of the smaller hose. Remove the hose and look for any fuel coming out of it; these have a diaphragm which can break and cause rough running.

The thicker hose runs to the EVAP Purge Solenoid, just for your information.

Oscar.

[rjinmt]

I replaced the mass air flow, map sensor, plenum gasket and now I only get miss fire on number 6

[tblake]

You jumped the gun and replaced all those sensors especially the MAF with how spendy it is?

Did you check for gas in the fuel pressure regulator vacuum line as Oscar mentioned?

Also how is your coolant level?

[rjinmt]

i checked the fuel pressure reg and it isn't leaking anything out of it. ya so far I am 400 into the car but was kind of expecting it sooner or later since it is at 198k the maf sensor alone was 140 the coolant is fine I have been running a leak preventer to hopefully keep the blown gasket thing from happening that these things are prone to and so far so good!!

[rjinmt]

i switched injectors 5&6 around thinking it may be a bad injector but it is still doing it, it does have a horrible exhaust leak somewhere on back side but I am having a horrible time finding it

[tblake]

Sorry to say it but you could have a blown head gasket and that could be the "exhaust" leak you are hearing. Have you checked compression on #6?

[rjinmt]

compression 165+1-5cylinders, 0 in number six with piston movement... started it up this morning and did a cold test on the scanner and came up with o2 right bank and miss fire number 6, stuck exhaust valve????

[rjinmt]

well I am going to pull of the valve cover on the even side today and see if I can figure this out so if anyone has any ideas before I get started let me know. I am hoping. to get some input on how to do this without pulling the motor and if anyone knows the specs for the arms or lash I would appreciate it..thanks guys

[tblake]

I wonder if your head gasket blew for number 6 allowing compression to leak out like in the pictures. That could also explain your exhaust leak.