vavumn for audiovox cruise

[becoyote]

Finishing up my install and just wanted to know if the general consensus was that 1 vacuum port was enough to draw from? I am using a resevoir tank, but have read installs that either used 1 or 4 ports and 1 that took vacuum from the map sensor.

Thanks!

 

[ionbeam]

There will be no consensus on this question. One port is scantly adequate but does work. Two ports gives you some reserve capacity for bigger loads, mountain roads and higher speeds. IMO, using the MAP sensor's vacuum line is a bad idea. It's not a lot of work to set up two ports so why not? I have used one, two and four ports. One port here in New England wasn't enough. I noticed little difference between two and four ports.

 

[becoyote]

There will be no consensus on this question. One port is scantly adequate but does work. Two ports gives you some reserve capacity for bigger loads, mountain roads and higher speeds. IMO, using the MAP sensor's vacuum line is a bad idea. It's not a lot of work to set up two ports so why not? I have used one, two and four ports. One port here in New England wasn't enough. I noticed little difference between two and four ports.

Okay, so if I use two ports, does it matter which two? Separate check valve for each right?

 

[ionbeam]

Okay, so if I use two ports, does it matter which two? Separate check valve for each right?

It doesn't matter which two. Use separate check valves or you will in effect be joining two sync ports together.

 

[Richouse]

IMO, using the MAP sensor's vacuum line is a bad idea.

Just curious as to why???? I have mine T into this line with no ill effects to my knowledge..

 

[ionbeam]

IMO, using the MAP sensor's vacuum line is a bad idea.

Just curious as to why???? I have mine T into this line with no ill effects to my knowledge..

MAP = Manifold Absolute Pressure In our FJR they simply call it the Intake Air Pressure Sensor. The FSM says, quote:

Intake air pressure sensor

The intake air pressure sensor is used for measuring the intake air volume. The intake air volume of

every intake stroke is proportionate to the intake air pressure. Therefore, the intake air volume can be

measured by measuring the intake air pressure. The intake air pressure sensor converts the measured

intake air pressure into electrical signals and sends those signals to the ECU. When the intake

air pressure is introduced into the sensor unit, which contains a vacuum chamber on one side of the

silicon diaphragm, the silicon chip that is mounted on the silicon diaphragm converts the intake air

pressure into electrical signals. Then, an integrated circuit (IC) amplifies and adjusts the signals and

makes temperature compensations, in order to generate electrical signals that are proportionate to

the pressure.

If the operation of the AVCC causes the pressure at the IAP to vary, part of the information that the ECU uses for fuel mapping will be wrong. The ECU has a default table that it uses if the IAP reading goes out of range. I have run my FJR with this sensor unplugged as a step in troubleshooting a driveability issue and if I didn't know that it was unplugged I never would have known from the way it ran due to the look up table. I have also run my engine with a mechanic's vacuum gauge teed into a bunch of sensors and regulators so I could watch it as I rode my bike. The IAP is indeed a fairly dynamic sensor and I personally wouldn't want to mess with it. YMMV.

 

[becoyote]

Thanks for the reply.

All finished now.

 

[UselessPickles]

One benefit to using all 4 ports for the cruise control (beside the obvious good feelings that come with symmetry) is that it becomes very easy to get to those ports for a throttle body sync. No more fiddling with those tiny rubber caps and retainer clips!

 

[Richouse]

IMO, using the MAP sensor's vacuum line is a bad idea.

Just curious as to why???? I have mine T into this line with no ill effects to my knowledge..

MAP = Manifold Absolute Pressure In our FJR they simply call it the Intake Air Pressure Sensor. The FSM says, quote:

Intake air pressure sensor

The intake air pressure sensor is used for measuring the intake air volume. The intake air volume of

every intake stroke is proportionate to the intake air pressure. Therefore, the intake air volume can be

measured by measuring the intake air pressure. The intake air pressure sensor converts the measured

intake air pressure into electrical signals and sends those signals to the ECU. When the intake

air pressure is introduced into the sensor unit, which contains a vacuum chamber on one side of the

silicon diaphragm, the silicon chip that is mounted on the silicon diaphragm converts the intake air

pressure into electrical signals. Then, an integrated circuit (IC) amplifies and adjusts the signals and

makes temperature compensations, in order to generate electrical signals that are proportionate to

the pressure.

If the operation of the AVCC causes the pressure at the IAP to vary, part of the information that the ECU uses for fuel mapping will be wrong. The ECU has a default table that it uses if the IAP reading goes out of range. I have run my FJR with this sensor unplugged as a step in troubleshooting a driveability issue and if I didn't know that it was unplugged I never would have known from the way it ran due to the look up table. I have also run my engine with a mechanic's vacuum gauge teed into a bunch of sensors and regulators so I could watch it as I rode my bike. The IAP is indeed a fairly dynamic sensor and I personally wouldn't want to mess with it. YMMV.

Hmmm, I wonder if this is why I had such a bitch of a time trying to sync the throttle bodies. I had a 300rpm surge AT IDLE that I almost couldn't get to smooth out. Does this sensor have anything to do with the idle circuit???