pcv + blower = high idle ...

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Feb 1, 2006

#1

• Feb 1, 2006

• #1

i am becoming more and more convinced that my blower is sucking hard enough even at idle that it is getting air through the valve cover vent and up through the pcv. i believe that this is causing 2 problems:

1. oil getting sucked into the intake.
2. idle too high.

to test this theory, i completely blocked of the iac and it still idled. i could feel air getting sucked in through the valve cover vent. then i vented the pcv to the atmosphere and blocked off the port the pcv tube was connected to. sure enough, the idle went to 800, right where i told it to be.

i believe this proves my theory, but is there another test i can do to prove it another way?

i would love to just leave it that way (pcv vented to the atmosphere), but i am worried that there will be too much crankcase pressure and the oil will come through the valve cover gasgets again.

i'm considering trying to find or break a pcv valve such that it is always open. then i can vent it to the atmosphere, and any crankcase pressure caused by the blower should be free to escape which would solve the above worry about too much crankcase pressure.

what would you do?

 

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Feb 2, 2006

#2

• Feb 2, 2006

• #2

ttt

 

95cobraguy

Member

Dec 23, 2005

637

11

19

Concord, NC by way of LI, NY

Feb 2, 2006

#3

• Feb 2, 2006

• #3

are u using an oil separator?

 

final5-0

Mustang Master

Apr 6, 2003

6,817

12

79

DFW Texas

Feb 2, 2006

#4

• Feb 2, 2006

• #4

BlackVert said:

i am becoming more and more convinced that my blower is sucking hard enough even at idle that it is getting air through the valve cover vent and up through the pcv. i believe that this is causing 2 problems:

1. oil getting sucked into the intake.
2. idle too high.

to test this theory, i completely blocked of the iac and it still idled. i could feel air getting sucked in through the valve cover vent. then i vented the pcv to the atmosphere and blocked off the port the pcv tube was connected to. sure enough, the idle went to 800, right where i told it to be.

i believe this proves my theory, but is there another test i can do to prove it another way?

i would love to just leave it that way (pcv vented to the atmosphere), but i am worried that there will be too much crankcase pressure and the oil will come through the valve cover gasgets again.

i'm considering trying to find or break a pcv valve such that it is always open. then i can vent it to the atmosphere, and any crankcase pressure caused by the blower should be free to escape which would solve the above worry about too much crankcase pressure.

what would you do?

Click to expand...

I'll be the first to say I just don't know the answer
however
If what you say is true, all other KB combos do the same thing.

I don't remember seeing any other threads along these lines.

Grady

 

KBCobra95

New Member

Aug 28, 2005

356

0

0

North Carolina

Feb 3, 2006

#5

• Feb 3, 2006

• #5

Why not just mess with the idle screw?

 

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Feb 3, 2006

#6

• Feb 3, 2006

• #6

95cobraguy said:

are u using an oil separator?

Click to expand...

no, i don't have an oil seperator ... i should get an oil seperator.

KBCobra95 said:

Why not just mess with the idle screw?

Click to expand...

that was the first thing i did, it didn't help.

then i disconnected the iac (the connector), still no help.

then i completely blocked off the iac with a piece solid plastic where the gasket goes. it was harder to start and the idle did go down, but it still idled.

then i disconnected the pcv and blocked off the vacuum inlet for it.

with the iac blocked off and the pcv valve disconnected, it would not start without opening the throttle a little. once it was running, it would almost die when i would close the throttle. it was clearly not getting enough air.

the i reconnected the pcv. and disconnected the valve cover vent, leaving it open. it started without having to open the throttle, like before.

i could feel the air getting sucked into the valve cover vent. when i blocked it off, the idle went down. when i took my finger off, it whistled for a few seconds (until it was caught up with the vacuum), then it stopped whistling but there was still air getting sucked in.

to me it really seems like enough air is coming through the valve cover vent and through the pcv keep me from being able to get it to idle below 1000.

maybe this is normal, but i would really like to be able to control my idle and set it to 800 if i want.

 

KBCobra95

New Member

Aug 28, 2005

356

0

0

North Carolina

Feb 3, 2006

#7

• Feb 3, 2006

• #7

Have you looked into the iac block off plates? The have smaller holes I believe and are may help work with your idle issues? I have a breather on mine so maybe you could try that?

 

DarkProphet

Founding Member

Aug 19, 2002

391

0

0

Quakertown, PA

Feb 3, 2006

#8

• Feb 3, 2006

• #8

Ive also heard of using a turbocoupe (i belive) PCV because they seal better, not sure though.

 

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Feb 3, 2006

#9

• Feb 3, 2006

• #9

KBCobra95 said:

Have you looked into the iac block off plates? The have smaller holes I believe and may help work with your idle issues. I have a breather on mine so maybe you could try that?

Click to expand...

i just got one a few days ago actually, thanks to R.J., but i haven't installed it yet.

you have a breather on what? the valve cover vent?

what is your idle set to?

 

95cobraguy

Member

Dec 23, 2005

637

11

19

Concord, NC by way of LI, NY

Feb 3, 2006

#10

• Feb 3, 2006

• #10

i was playing with my oil separator yesterday, basically just mounting it to the firewall with a stupid L bracket i made and i took the filter element out and noticed in just the short time i drove it afterwards that more oil had collected than previously. i would get an oil separtor to start, it should clear up any oil being drawn into the intake.

 

KBCobra95

New Member

Aug 28, 2005

356

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0

North Carolina

Feb 3, 2006

#11

• Feb 3, 2006

• #11

I have a breather on my valve cover vent, as well as a oil seperator. Idle is around 850-900.

 

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Feb 8, 2006

#12

• Feb 8, 2006

• #12

looks like the high idle was from my cruise control cable not letting the throttle close completely.

 

KBCobra95

New Member

Aug 28, 2005

356

0

0

North Carolina

Feb 9, 2006

#13

• Feb 9, 2006

• #13

So the cruise cable is too short?? I thought it was supposed to work? Did you switch to a fox TB?

 

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Feb 9, 2006

#14

• Feb 9, 2006

• #14

KBCobra95 said:

So the cruise cable is too short?? I thought it was supposed to work? Did you switch to a fox TB?

Click to expand...

i'm thinking that the distance from the place where the bracket holds the cable to the throttle actuator was not exactly the same from my old setup to the new setup.

the elbow and the throttle body both changed when i installed the blower, so it doesn't surprise me that the distance wouldn't be exactly the same. i just didn't think to check it and i didn't notice that there was no slack there.

i bent the bracket towards the actuator a little which put some slack into the cable and now it's happy.

 

95cobraguy

Member

Dec 23, 2005

637

11

19

Concord, NC by way of LI, NY

Feb 9, 2006

#15

• Feb 9, 2006

• #15

if u dont use the cruise control u could always remove the cable.