SMac770

Well, the start of the video pretty much says it. The flaps are supposed to be in one position and are in the other position. At idle, when the specified is 0%, the actual should be more like 9%, not 99%. It could be the solenoid passing vacuum to the flaps is broken and always passing vacuum. It could be the flaps are broken and stuck in the "open" position.

I'd start by pulling the vacuum line from the solenoid off the actuator and putting a vacuum gauge on it. You should measure no vacuum at idle and something like 28 inHg (950 mbar) when you rev up (when specified is 99%). If you're measuring vacuum all the time, replace the solenoid. You have to hold the high idle for 3 seconds, the full vacuum reading doesn't come instantly. It looks like the newer ones have the line from the solenoid to the actuator built into the actuator, so you might not be able to pull that off. So you'll need to pull the line off the solenoid and connect your own vacuum line between the solenoid output and the gauge. If you have the updated solenoid with the vent line, don't confuse the solenoid input line vs the output line vs the vent line.

If the vacuum from the solenoid to the actuator is being correctly managed, then it has to be something with the flaps in the intake manifold itself. Can you manually move the actuator arm? youtu.be/5IVxPqriZkk?t=132 So the rest position is spring loaded, then the vacuum pulls the arm back (towards the actuator bulb). When you do that, you should see the flap value in VCDS change. If the arm is jacked and not moving, new intake manifold. If the arm is moving, but the reading does not change, probably a new intake manifold. But at that point, you'd remove the intake manifold and see if the flaps are actually moving with the arm. If the flaps are moving with the arm (you can even actuate the arm yourself using a vacuum pump) and the the vacuum is actuating the arm, that just leaves the sensor.

The sensor is just a poteniometer aka voltage divider. 5v on 1, ground on 3, output signal on 2. The output signal is just a partial of the 5v, varied based on angle. You can access these measurements without pulling the IM, but there's no point until you've visually verified the flaps are actually moving their full range correctly by removing the IM and looking. https://www.ecstuning.com/b-genuine-...or/07l907386b/

SMac770

On the sensor, looks like the resistance measurements you should see, if it's in the rest state and working, is 204-284Ω between 2 and 1 and 7-25Ω between 2 and 3. This is how the ECM is thinking the flaps are in the open state instead of the closed/rest state. It sees the voltage coming in on pin 2 and it's not intelligible based on it should be a set fraction of the 5v on 1. Instead, it's seeing a high voltage all the time, so it thinks the flaps are rotated all the time. It could be the sensor has shorted out, if the flaps are moving with vacuum correctly.

vegg

Thank you again. I went out and bough a 15 dollar gauge with a hose, unplugged the line from the actuator and connected the gauge. The second I put the key in the ignition it went off, spun around several times even. 12-13 inHg at idle, before even starting the engine and 30+ while reving, IF I understand the readings correctly. I have attached a zip with a picture of the readings while idle and a video while reving for a while. If I understand this correctly, it is not doing its job.

The arm itself works fine when I move it manually.

SMac770

https://www.audizine.com/forum/showt...1#post13792031

If you look at the second picture, which shows the intake manifold runner solenoid, you see there's the red lined hose from the actuator to the output port (downward port) on the solenoid. Then there's the hose which I marked with an orange line that comes from the vacuum system, from the vacuum pump on the back left of the cylinder head. This is on the input port (horizontal port).

I presume you pulled the red lined hose off the solenoid and connected your gauge to that downward facing output port? I have no idea why your gauge would move at all until the engine was started. Maybe turning on the electrical caused the solenoid to activate, passing residual vacuum to the gauge? If that's the case, I'd wonder if the wiring to the solenoid is not shorted to 12v and so the solenoid is activated all the time the ignition is on. The gauge should have stayed "dead", around 0, until you revved the engine up past 3k. We see the solenoid pass a good 30 inHg at that point, as expected. But on rev drop, it continues to sit high vacuum instead of returning to 0.

It's probably just a failed solenoid. These things can develop corrosion internally; that's why the newer versions have a third port, a vent line to outside air. This is the port that is over the electrical plug. But with a 2013 CFKA, I'd expect you should already have that version of solenoid.
https://parts.audiusa.com/p/48001654/06H906283B.html

I think the one thing I'd check before calling it a good night for your old N316 solenoid is the power on the plug. Pin 1 should be constant 12v, pin 2 should be floating, grounded when the ECM wants to activate the solenoid. So if you pull the off with engine on, do you measure 12v to ground on pin 1? Do you measure any voltage from pin 1 to pin 2 with the engine idling? Do you measure 12v from pin 1 to pin 2 when you rev the engine past 3k? If you're measuring voltage from pin 1 to pin 2 on the plug when the engine is just idling, there's probably a grounding issue on the green/purple wire back to the ECM, so it's grounding all the time instead of only when the ECM wants to (when over 3k).

SMac770

I do wonder if it's possible the actuator is not allowing the vacuum on the line to equalize after the solenoid stops supplying vacuum. I wonder if the actuator can get clogged. Did you look at the physical arm to see what it's doing? Is it being held in the activated state? With the red line unplugged, does it release to the rest state? If not, can you pull it to the rest state?

SMac770

You know, if you do have that vent port version of the solenoid, did you plug or clog that vent line (end sits on top of the engine in front of the PCV)? I now recall another thread once where the guy had idle issues and turned out he had decided to plug that vent for whatever reason. I wonder if he was having the load flaps opened all the time in the same manner you are experiencing.

vegg

I changed the solenoid today and the problem remained the same, and I got kind of dishearted. That vent line however, it confused me, since as you say, it doesnt look like it is able to let any air out. So I tried just removing it completely, and VOILA, it works perfectly again...

There is a white sort of cap on it that I dont understand at all, I'll attach pictures.





In the schematics for the engine no such line exists as far as I can see. I dont understand why it would be plugged at all either? I havent touched anything.

Edit: With the right schematics there obviously is a vent line (https://audi.7zap.com/en/usa/audi+a4.../1/133-133022/)

SMac770

I have a B8.0, so I don't have the vent line to investigate. I only know that it's been posted before that plugging it messed up the load flap operation.

https://www.audizine.com/forum/showt...B8-5-Flex-Fuel
I wonder if the stuff that's missing on yours sucked down the vent hole or otherwise clogged it?

I don't have one, so I don't know if it's like a valve that toggles between open and closed based on vacuum or pressure.

There's apparently two different ones, a rev B and a rev F: https://parts.audiusa.com/productSea...Term=06h133583
B is the one in the parts catalog for this engine; no idea what an F is for.

youtu.be/wI9WuLx_oiw
I assume the white material is maybe porous? Hard to speculate from Internet pics.

Glad at least your engine operation issue cause has been identified. :-)