Replacing VVT on B8 A4?

[NickSTI7]

Hey Everyone, so I've been struggling forever with fixing my Gf's A4, it's got a rough idle with misfire codes being thrown on all cylinders, replaced spark plugs, coils, PCV, etc. Codes are not always the same, but often after clearing them, the first ones to pop up are "Cold Start Idle Control" and multiple misfire codes. Sometimes it will throw either a Camshaft Position Sensor or Crankshaft position sensor, but I've replaced them both and checked timing and its all g. Now, today, just saw a video https://www.youtube.com/watch?v=SrYQ3Xe858c and the guy said he had replaced that N205 I think it is, or that bolt that bolts into the camshaft intake side, front of the motor, it's behind that round cover on the front of the 2.0tsfi engines. Question is, is there a way to identify if that's actually the problem? Is there anything I can log in VCDS to help me narrow it down? Thanks

[Spawne32]

There are multiple N205 valves, they control the variable valve lift, not the VVT. The VVT is controlled by 3 things, the oil control valve, which sits behind the the cam adjuster magnet. (https://www.ecstuning.com/b-febi-par...6j109259a~feb/) the magnet controls the movement of the control valve which regulators oil flow through the cam bridge. List which codes the car is throwing and that should narrow it down, the problem may be worse then you realize if the cam bridge filter screen has broken loose like in this photo, then the bridge needs to be removed and inspected and the piece retrieved and the bridge replaced.

[NickSTI7]

Alrighty then. Is it possible to see that screen without removing the bridge, or do I have to take it all apart?

[Spawne32]

Alrighty then. Is it possible to see that screen without removing the bridge, or do I have to take it all apart?

gotta take it apart, the bridge is pressed up against the block on that side where the oil passages are.

[NickSTI7]

Blah gotcha, and I'm assuming that entitles taking the timing chain off is that right?

[Spawne32]

Blah gotcha, and I'm assuming that entitles taking the timing chain off is that right?

I don't believe the chain has to come off to take the bridge off, but you do need the tool for the oil control solenoid which is left hand thread as well.

[NickSTI7]

Ah nice gotcha! Helpful video thanks. Man I hope I can get to the bottom of this idle issue soon. Like on a completely cold start, it'll idle fine for maybe a minute or two, but after that it starts missing prettyy bad. Also, sounds like a diesel when at idle, which I don't remember from before this all happened.

[cybernet99]

I Had the same problem, had to replace the part that was in the film canister in the video. Easiest way to check to see if this will fix the misfire at idle problem is to just loosen off the three bolts for the front plate and start the car ... if the idle is much smoother, then that is the problem. Oil will leak out while the motor is running and the plate is loose.

N205 I believe, cam position sensor.
Here is a link to a video of my car idling before I replaced the N205.

The reason I had to change the sensor was a failed cam bridge screen, the same problem as spawne32 has posted above. Some of the screen gets inside the N205, and causes it to advance the cam at idle.

[A4x]

Ah nice gotcha! Helpful video thanks. Man I hope I can get to the bottom of this idle issue soon. Like on a completely cold start, it'll idle fine for maybe a minute or two, but after that it starts missing prettyy bad. Also, sounds like a diesel when at idle, which I don't remember from before this all happened.

Could it be one of the exhaust camshaft solenoids that is stuck? You know, the ones that activate the Audi valve lift on the exhaust cam. Pretty simple fix if it is this.

On a normal cold start, it will idle with the high cam lift profile activated. After a minute or two, it should switch over to the low lift profile. Maybe you have an issue switching over causing the misfires.

[Spawne32]

Arent the N205's the solenoids for the VVL or am I thinking of a different part?

[NickSTI7]

Super good thought, and I actually just finished watching a video on Charles (Humble Mechanic) and Engineering Explained give a presentation on this VVL and VVT tech.

[NickSTI7]

When you say simple fix, do you mean just swapping out the solenoids or, is there a way to diagnose that it is indeed one of these solenoids?

[Spawne32]

When you say simple fix, do you mean just swapping out the solenoids or, is there a way to diagnose that it is indeed one of these solenoids?

We gotta know the actual codes that you are getting before we can point to a specific one.

[NickSTI7]

We gotta know the actual codes that you are getting before we can point to a specific one.

I'll pull them in an hour or two, getting a full battery charge right now as the car has been sitting for a while and apparently it had a pretty low battery.

[Justin B8]

Arent the N205's the solenoids for the VVL or am I thinking of a different part?

Correct.

The exhaust "cam" is actually a splined shaft with 4 separate tubular sliding pieces on it. Each of these sliding pieces have a pair of cam lobes and a helical "ramp" for a solenoid "finger". The solenoids deploy a finger that rides the ramp causing the lobed tube to slide along the splines, a detent ball locks them in place. All 8 solenoids are independently controlled. At low rpm, the low lift set of lobes is used, while at higher rpm (3500+) the high lift lobes are used. When revs drop, the solenoids push the lobed tubes back along the shaft engaging the low-lift lobes. It's a more sophisticated version of Honda's VTEC.

[NickSTI7]

I Had the same problem, had to replace the part that was in the film canister in the video. Easiest way to check to see if this will fix the misfire at idle problem is to just loosen off the three bolts for the front plate and start the car ... if the idle is much smoother, then that is the problem. Oil will leak out while the motor is running and the plate is loose.

N205 I believe, cam position sensor.
Here is a link to a video of my car idling before I replaced the N205.

The reason I had to change the sensor was a failed cam bridge screen, the same problem as spawne32 has posted above. Some of the screen gets inside the N205, and causes it to advance the cam at idle.

Nice! I'm gonna try this and see what happens. Let ya know today yet

[jfo]

The term N205 seems to be used for two different parts on various sites. The manual refers to the cam adjustment magnet on the front of the B8 engine as N205 and the exhaust cam solenoids as cam adjustment actuators. Some vendors call these actuators N205 valves.

[NickSTI7]

Just wanted to update everyone on this, I unbolted that magnet that's on the front of the engine, just left it in there partially, and started er up. Ran like a top. So, moving forward, is that actuator valve faulty then, can I just order a new one and put it in, or would it be wise to take the upper timing chain cover off, unbolt the cam bridge and take a look at the screen?

[pf_lewis]

Just wanted to update everyone on this, I unbolted that magnet that's on the front of the engine, just left it in there partially, and started er up. Ran like a top. So, moving forward, is that actuator valve faulty then, can I just order a new one and put it in, or would it be wise to take the upper timing chain cover off, unbolt the cam bridge and take a look at the screen?

Did you ever remedy your situation? I'm currently in the midst of having the same issue. waiting for the special cam control valve socket to come from amazon (*sigh*) so I can remove the control valve and then the bridge to check on status of my screen.

[Theiceman]

Post a pic of the 4/3 valve ( the area behind the solenoid n205)


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[Smac770]

PF, which part did you order? The T10352C comes with five different tools, https://audi.snapon.com/SpecialTools...temId=59020123, and the repair manual says could be /1A (it actually says /1, I assume /1 has been replaced by /1A) or could be /2 depending on version. I should probably have looked more closely when I had my N205 dismounted, but I didn't. 3rd party kits tend to only include one tool, and they tend to look like the pins are straight across. But /1A and /2, neither look straight across in the snapon image.

[Theiceman]

I will show my kit tomorrow. 2014:and 2010 are definitely different




i have used the silver and gold one ( 2010/2014 )

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[dalmation53]

were you only getting cold start misfires by any chance?

Just wanted to update everyone on this, I unbolted that magnet that's on the front of the engine, just left it in there partially, and started er up. Ran like a top. So, moving forward, is that actuator valve faulty then, can I just order a new one and put it in, or would it be wise to take the upper timing chain cover off, unbolt the cam bridge and take a look at the screen?