[darioc]

My 99 golf has been going into limp mode while on the highway for quite some time now. I'm in the process of purchasing a ross-tech cable, but until then the generic codes I have are 1441, 1549, and 1550. I have removed the n18, and will eventually remove the egr cooler and pipes so that is why the egr code is present. I have replaced the n75 and all vacuum lines and am now onto the turbo. On startup, the vnt arm/rod moves very slightly and not at all when revving the engine. I can move it by hand about 1/2" but it has some resistance. My next step is to disconnect the rod from the arm for the vanes and see how easily the arm moves. Should the arm/rod move when revving the motor? Should there be any resistance on either? The vnt does hold vacuum and the car drives well, aside from slowdown shudder and a bad trans mount causing some unwanted movement.

Any ideas or other ways to test the vnt? If I have to remove the turbo and clean it, so be it. But if I don't have to, all the better

 

[darioc]

First, get the VCDS and do some more datalogging. Then worry about replacing stuff.

It should move when revving the engine. If you can move it by hand 1/2", you're getting full travel. It's hard to describe proper spring resistance by writing about it, but it should be able to be pressed down by hand force against the spring inside the VNT can. It should return to start by itself.

These codes below, clear them with VCDS and see if they come back.

1411 is EGR Vacuum Regulator Solenoid Valve Open/Short To Ground. Check for shorts.

1549 is Boost Pressure Contr. Valve short to ground . This is N75, it may go away since you replaced the N75

BTW, I also saw this posted elsewhere and the video showing movement and the video I have here:

http://www.myturbodiesel.com/1000q_how_to/a4/VNTadjust.htm

could be a bit misleading since the lever isn't attached to the can and the spring. In the video, I was moving the lever with a piece of fishing wire, to give you an idea of how light it should move with the lever removed from the spring loaded can.

Ross tech cable is on the way, so datalogging will be done asap. The egr code I am not worried about. I removed the n18 after breaking it and knew that the light would come on for that. The 1549 and 1550 codes are what I am relying on to diagnose my limp mode issue. What would you recommend I log when the cable arrives?

The arm moves slowly to its limit on startup, but when revving it does not budge. However, I can press it down by hand and it springs back to position like you are describing.

Get a open 14mm wrench hook it up on the top vnt rod upper connection and push it up and down carefully until you free it up, and continue excercise it for about 10min.

I wonder if this is necessary seeing as though it does seem to be "free" because it moves on startup and when depressed by hand. You would recommend I do this if it was completely stuck correct?

 

[darioc]

Even if it's not stuck it couldn't hurt. This is a useful test either way. You should feel smooth resistance against the spring inside the VNT actuator can.

I'll give it a shot at lunchtime.

 

[darioc]

i do excercise the rod to my car eventhough I step on it like I stole it, so Like Chitty said it doesn not hurt anything.

I am hoping that I did not enter limp mode for that day or two because I had exercised the arm the day before. I will exercise/lube the arm today before I leave work and see if I enter limp mode on the way home. However, even if exercising the arm does help and I don't go into limp mode, there is still no way of knowing whether or not it is the actuator or the turbo vanes without disconnecting the arm from the vane lever correct?

 

[darioc]

Well what do you know? I lubed the arm and moved it some by hand and I did not go into limp mode on the highway. Do you think I just have some rust on the arm/lever that is not allowing full movement? I still don't think that I have a full range of motion in that arm... I am not even sure if I have 1/2" of movement. Gonna take a closer look this afternoon.

 

[darioc]

Remove the arm and move it by hand - that will tell you right away how much resistance there is. There shouldn't be any when the arm is disconnected.

Ok, and obviously, with the arm disconnected, resistance means new actuator, no resistance means clogged vanes aka turbo cleaning.

Please be resistance, please be resistance, please!

 

[darioc]

Why would you WANT resistance? If the lever on the turbo is separated from the VNT can then the lever should have no resistance either way.

No I am hoping there is resistance in the arm for the vnt can, not the lever for the turbo vanes...

 

[darioc]

If I were you I would excerise the vnt rod more with a 14mm wrench instead of the finger, of course you'd need to go easy up and down, if you do it careful it would get freed up in a few tries,,,, then get in your car and drive it like you stole it shifting in high RPM's, that would clean it up imediatly

What is the significance of the 14mm wrench? I looked again at the arm this weekend and didn't see any 14mm bolts...