Car runs better w/ PCV disconnected ?!?

[Orion1123]

My Cobra has had a rough idle since I bought it 6 months ago. About one month ago I was playing w/ some of the vacuum lines, just checking them to make sure they were connected. They all seemed fine. After that the idle problem seemed to almost dissappear. One of my friends told me to replace the PCV valve, so I did that today. When I went to disconnect the PCV valve, it was already out of the intake maifold. I replaced it with a new one and reconnected it. After starting the car up and driving it the idle problem was back. So I decided to pull the valve out of the manifold and that seemed to level the idle out. W/ the valve instaled the idle lopes b/w 600- 900 RPM. W/ the valve out, it idles around 800 RPM. Any help on this matter would be appreciated

 

[lone sailor]

I'm interested in the solution to this problem as well. I've heard quite a few 94/95's were having this trouble also.

 

[BADBOYSPACK]

a clogged hose to the pcv valve and behind the intake about right in the middle is a metal screen that is almost never changed, try looking at it or replacing it. carbon build up in the throttle body and or the iac valve

 

[alotahp92gt]

a clogged hose to the pcv valve and behind the intake about right in the middle is a metal screen that is almost never changed, try looking at it or replacing it. carbon build up in the throttle body and or the iac valve

I agree.

Do you have a breather on the oil fill tube??? Or just the stock cap? Is there a line running form the fill tube to the TB? If you have the stock cap. and the tube is running to the TB then check all the tubes and be sure they are all serviceable and not clogged. Do you have a stock intake? If you have an aftermarket intake be sure the routing of the vac lines are correct. For instance the vac tube on a stock intake that connects to the vac tree on the fire wall, comes out of the front. but on my Holley systemax intake the same hose that runs to vac tree on the stocker... now runs to the PVC and the backside vac line that ran to the PCV now runs to the main on the vac tree. I chased the same problem for months and finally figured it out by checking out my intake's vac hose routting on line.

How ever if you have a stocker and all lines are running correct, then most likely the screen and hoses are to blame. You may want to check the EGR spacer and TB to see if you have any buildup. Anouther prob I had was the Idle bypass ... (the thing hanging off the side of the TB and has wires connected to it)... was going bad, the car would hunt for an idle, and tend to have the problems you have described. But I would check your vac hoses first.
Brian

 

[Orion1123]

I do have the stock mainifold setup. I have already taken the throttle body and IAC Valve off and cleaned them, I could try replacing the IAC Valve, but I didn't think that would go bad. Also, I checked the hose that the PCV valve is connected to and the hose does not seem clogged b/c it was sucking a lot of air when I removed the PCV valve while the car was running. The screen you are talking about is in the intake manifold where the PCV valve goes in, correct? Can this screen be replaced or just cleaned? Does it just pop out?

 

[Teal93svt]

i have a question where is the pcv valve located is there a house i can follow to find it. i have searched all over for it. thanks for your alls help.

Bobby

 

[alotahp92gt]

stand on drivers side fender. You are now looking at the runner side of the upper intake. Now find the firewall, ok good... now lean over toward the upper intake and look between the firewall and the rear... pointing toward the rear of the car against the firewall... see the bell houseing, find dead center and trace up towards the top of the lower intake... thats the bottom half of the intake manifold... there hould be a grommett with a little tube pointing out of it on the back side, it should have a hose attached that is running to the EGR spacer. The hole is about the size of a quarter. you should be able to disconnect the vac hose, and pull out the PCV , you may hav eto get a screwdriver to pry out the grommett, that is the best way...besides pulling off the upper and lower intake... to change out the screen. Now it is kinda hard to locate with all the emissions, vac lines, and general junk that is hanging out the back side of the motor but you will find it... I hope my round about way works for you!!!


PS you could go to autozone and get a blow up of where it goes and then prob solved

 

[Teal93svt]

cool thanks.

Bobby

 

[alotahp92gt]

did you find it?

 

[Teal93svt]

the funny thing is no, the ac hose runs behind there where im trying to look down. and im afraid to move it to much. dont want to bust the line.

Bobby

 

[alotahp92gt]

try from the other side, remove your intake hose off the air box and TB, if you want remove the throtle linkage and pull the tb a nd egr off all at onece. you should have no problem finding it. But you can move the ac line a good deal w/o dammageing it

 

[BADBOYSPACK]

This screen is so over looked by so many people, and a doubt most mustand people even know its there, but it does need to be changed and does get clogged up !
Like all stangs even cobra get drivin like our great grandma would drive them, NOT

 

[Orion1123]

does the screen just pop out? or is it conected somehow?

 

[BADBOYSPACK]

use a course tool to sort of like screw it in the screen, then pull it out

 

[Orion1123]

can the screen be cleaned, or does it need replaced?

 

[lone sailor]

can the screen be cleaned, or does it need replaced?

I usually clean mine out with carb cleaner or something of that nature.

 

[BADBOYSPACK]

for the dollar amount it costs, I would just change it

 

[PJM99]

My car was lopping pretty bad for sometime. I changed the plugs, wires, cap and rotor. Moved the timing to 12-14 degrees and it runs great now.

 

[Orion1123]

I just took out the screen to replace it and it was covered in oil. Does this sound right? or do I have a problem somewhere else? Thanks

 

[lone sailor]

I just took out the screen to replace it and it was covered in oil. Does this sound right? or do I have a problem somewhere else? Thanks

That is the typical problem everyone is reffering to. Cleaning it out or replacing it after a substancial amount of time gives you the best results.