Audi A4 2005 3.0FWD (How do you diagnosed the vacuum activator?
07-30-2018, 03:54 PM
#1
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Audi A4 2005 3.0FWD (How do you diagnosed the vacuum activator?
Hello,
I have an Audi 2005 A4 3.0L and it has been doing a lot of new problems that I would like to DIY. I am on a very low budget and going to an Audi dealer not possible at this time.
My car is vibrating a lot, in Park or Drive gear. I look all over the web for videos on the VA and nothing of substance. Can anyone out there explain how this VA works? I was fiddling with the vacuum hose and there weren't any suction or force of air.
someone, please explain how do I know I have a defective Vocuume activator.
I have an Audi 2005 A4 3.0L and it has been doing a lot of new problems that I would like to DIY. I am on a very low budget and going to an Audi dealer not possible at this time.
My car is vibrating a lot, in Park or Drive gear. I look all over the web for videos on the VA and nothing of substance. Can anyone out there explain how this VA works? I was fiddling with the vacuum hose and there weren't any suction or force of air.
someone, please explain how do I know I have a defective Vocuume activator.
07-30-2018, 05:21 PM
#2
AudiWorld Super User
I'm assuming that you are referring to the dual-length intake manifold actuator; if not, let me know.
Before you start the engine, the manifold rotor will be in the "high RPM" position. Then when you start the engine, the actuators should pull in and rotate the manifold rotor to the low-RPM position, giving better low-end torque. At about 4,000 RPM, the vacuum should release and springs in actuators will cause rotation to high-RPM for more torque at higher engine speeds. I found on my car that the actuator was always in high RPM position because of a split rubber diaphragm in one actuator. But why you have settled on the manifold changeover valve as your source for vibration? That's not the first thing I would think of.
Before you start the engine, the manifold rotor will be in the "high RPM" position. Then when you start the engine, the actuators should pull in and rotate the manifold rotor to the low-RPM position, giving better low-end torque. At about 4,000 RPM, the vacuum should release and springs in actuators will cause rotation to high-RPM for more torque at higher engine speeds. I found on my car that the actuator was always in high RPM position because of a split rubber diaphragm in one actuator. But why you have settled on the manifold changeover valve as your source for vibration? That's not the first thing I would think of.
07-30-2018, 09:45 PM
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I'm assuming that you are referring to the dual-length intake manifold actuator; if not, let me know.
Before you start the engine, the manifold rotor will be in the "high RPM" position. Then when you start the engine, the actuators should pull in and rotate the manifold rotor to the low-RPM position, giving better low-end torque. At about 4,000 RPM, the vacuum should release and springs in actuators will cause rotation to high-RPM for more torque at higher engine speeds. I found on my car that the actuator was always in high RPM position because of a split rubber diaphragm in one actuator. But why you have settled on the manifold changeover valve as your source for vibration? That's not the first thing I would think of.
Before you start the engine, the manifold rotor will be in the "high RPM" position. Then when you start the engine, the actuators should pull in and rotate the manifold rotor to the low-RPM position, giving better low-end torque. At about 4,000 RPM, the vacuum should release and springs in actuators will cause rotation to high-RPM for more torque at higher engine speeds. I found on my car that the actuator was always in high RPM position because of a split rubber diaphragm in one actuator. But why you have settled on the manifold changeover valve as your source for vibration? That's not the first thing I would think of.
Turbo510,
Thanks for replying, I want to start by saying I am not an expert in auto mechanics. However, I have watch a few DIY Youtube in doing minor fixes in saving a few dollars.
So in answering your question "But why you have settled on the manifold changeover valve as your source for vibration" I did watch a DIY video on youtube with a guy trying to diagnosed his I really don't have a clear answer for you. However these are the symptoms of the car below:
1. Sometimes when turn the ignition, the engine struggles to turn over.
2. When it does turn over on second attempt in starting, I smell gas fumes coming from the tailpipe.
3. Sometimes on startup, a puff of black smoke comes from the tailpipe.
What do you think causing these issues?
08-01-2018, 06:05 AM
#4
AudiWorld Super User
That could be lots of things, but one common one is a bad Coolant Temperature Sensor. If it fails so that the ECU reacts like the coolant is ice cold when its really not, too much fuel will be injected and the engine will be hard to start, and smell like gas.
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