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Bucking and Killing

DarkBlueZ

Hard-core CEG'er
Joined
Sep 6, 2007
Messages
1,285
Location
West Saint Paul, MN
I have a problem. When my zetec is idling it bucks, like its rpm's are going up and down and if i dont have my foot on the brake it bucks forward. Also when I'm braking the car tends to kill, be it on an on-ramp or going to a stop sign. There is a hissing noise coming from the car also. Can someone please help with this problem?

Thanks in advance

~Jared.
 
I have a problem. When my zetec is idling it bucks, like its rpm's are going up and down and if i dont have my foot on the brake it bucks forward. Also when I'm braking the car tends to kill, be it on an on-ramp or going to a stop sign. There is a hissing noise coming from the car also. Can someone please help with this problem?

Thanks in advance

~Jared.

You have a large vacuum leak. Check that air intake that you built and make sure it isn't leaking anywhere. That is what the hissing is. This is causing a lean condition keeping your car from idling properly. Any CEL's?
 
You have a large vacuum leak. Check that air intake that you built and make sure it isn't leaking anywhere. That is what the hissing is. This is causing a lean condition keeping your car from idling properly. Any CEL's?
I am thinking the same thing.
 
well it still sounds like you have a vacuum leak somewhere. probably a fairly large one at that.
 
find and follow all the vacuum lines off the intake manifold. the biggest one is likely to be the PCV valve line. it will run around to the other side of the engine behind the exhaust manifold.
 


This is the sounds of my car. At the beginning, its outside the car with the hissing, you cant hear it perfect, its much louder in person. If you listen hard you can hear it. Then I go into the car and i rev. You cant really hear it, but it bogs down when the RPM's go down. I rev a second time at the end and you will see the incar lights dim as the car dies. It kills when the RPM's decrease too quickly.
 


This is the sounds of my car. At the beginning, its outside the car with the hissing, you cant hear it perfect, its much louder in person. If you listen hard you can hear it. Then I go into the car and i rev. You cant really hear it, but it bogs down when the RPM's go down. I rev a second time at the end and you will see the incar lights dim as the car dies. It kills when the RPM's decrease too quickly.

Again, it's a vacuum leak. Try and search for that hissing sound while the car is running. If you can't locate it, spray some carb cleaner and run it then look again. We know it's not your intake because you said it was hissing before you installed it...good luck and let us know how you make out :)
 
On the bottom side of the intake manifold there is a vacuum line that is hard plastic that runs from the intake manifold off to the drivers side (it is visable from the bottom of the car.) this piece is prone to cracking and can cause your lean condition. what I did with it was cut off the hard plastic 2" or so away from the manifold and 2" away from the ending of the hard plastic line and replaced it with a hose that met the fitment requirements and clamped it down. Another possibility is your throttle body position sensor is going bad. I'd bet on a vacuum leak though as it is your most probable explanation.
 
found the problem and got it fixed for $18.99

P1000528.jpg
 
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