Strange "Air sucking" sound when starting

[92will]

Hey All,

I just bought a 2007 ZX4 with a rebuilt title. The air cleaner is cone shaped under the air box and looks like a K&N style filter. I do not know if this is stock or not, but I tried to look at a new air filter at walmart and it says the filter is not servicable, so maybe what I have is factory.

Anyway, when I start the car when it is cold, it makes a sucking sound for 20 to 40 seconds then slowly stops like a valve is closing. After that, it is silent and the engine just purrs right along like it should. When I turn off the car, it does the same sound for maybe 2 seconds. It will do this whether the engine is hot or not.

The problems is that it is really annoying when starting it cold, because it kind of sounds like a pulley turning with worn out bearings and makes the car sound like crap for the 20 to 40 seconds.

I have never owned a Focus before, and with this one being rebuilt, I have no idea what the air box and filter are suppose to look like.

Any thoughts?

[Sponsor]

[speedracer ZX3]

You have a cone filter on the end of your intake tube, thats what it sounds like. It allows the engine to breath a little better, allowing better airflow. This is probably why you hear a sucking sound. If you listen closely under acceleration youll must likely hear the same sound. When you start your car do the RPM stay high? 800-1400 rpms? this would mean your throttle body is also open larger causing the engine to breath in more air causing a sucking sound.

[mac.mogul]

If you had pics I'm sure someone could tell you what you've got. Cone filters are not stock so you've probably got a modified intake.

[92will]

Where does the stock filter go? I tried to take the top of the air box apart, but it did not look like the filter would go there. My filter is under the air box pretty low. It is only a few inches above the bottom of the bumper where the air dam? is. Matter of fact it is lightly rubbed by the auto transmission cable. (That brings up another issue...the tranny cable connector is broke so I have a zip tie holding it on the tranny lever.

Anyway, when I rev up the motor after it is warm, it does not make the sucking sound. Actually it only makes the sound when started when cold and when shutting it off. It sounds like a valve or something is closing to release pressure or something.

[tracer22j]

sounds like you got a hacked back together focus factory air filter in in behind the left front inner fender and is non serviable and if car wa wrecked in that area probably just put a filter on the bottom of mass air flow tube cause the filter box is like 250-300 bucks

[92will]

I have tried to find some pictures on what it suppose to look like but I have not found any yet. I will try to take pictures of mine and post it on here.

The sound is what is bothering me but the position of the filter is another concern because of how low it is. Our road sometimes floods when it rains hard and can get upto about 1 foot deep. I am afraid my daughter might drive through it one time and suck up some water and cause all kinds of problems.

[tracer22j]

better look for a factory one it has a snorkle that makes it suck the air from about the center of wheel well above where you would pick up water

[mac.mogul]

1st page of google searching for "2007 zx4"



If it doesn't look exactly like this then you need to post your own pictures so we can help you.

[tracer22j]

that isn't the air cleaner its down under thats just a resinator

[mac.mogul]

That is the stock air box. The filter is a flat type filter placed level with the bottom of the box cover.

If you have anything different than that, it is not stock.