[themiddlegeek]

Hi, new to the forum, and a new owner of an '05 Focus ST.

I recently put in a K&N Performance Filter Kit, and am having issues with a vacuum forming on the throttle when I am not pushing the pedal. The reason I suspect a vacuum is that when I jab the throttle, I hear a short *pss* sound.

There is no check engine light, and I made sure everything is secure, with no leaks. The filter does have a hydro-phobic cover from K&N, if that helps.

 

[gotta_gofast]

....yes of course there is a vacuum when you do not push the pedal.

 

[themiddlegeek]

....yes of course there is a vacuum when you do not push the pedal.

Yes, but this is a very hard vacuum. To the point where a hard push on the throttle is needed to accelerate.

 

[gotta_gofast]

Then there is friction holding your throttle plate closed. As vacuum would hold one half of the butterfly, the other half would be pulled by the vacuum nulling its effects. If you are convinced it is excessive vacuum throw a vacuum gauge on to verify. But your installation should have included replacing parts before the throttle body, not after. Check that the cable is pinched. If the accelerator pedal moves freely, you probably have a leak after your MAF sensor or a leak in your vacuum lines. K&N filters use oil by design, so in the long term you may notice stumbling or other MAF sensor related issues due to a dirty MAF element.

 

[amc49]

Impossible to create 'more' vacuum by adding a different TB. NORMAL vacuum is highest at idle with TB closed.

If throttle got tighter then you have the clamp tight enough you warped the plastic body to seize up the plate. Depending on the 'pss' sound, may be normal with a filter that does not silence like a normal airbox does.