16711 - Knock Sensor 1 (G61): Signal too Low on 1.8T

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vdubdezl

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Sounds like full ON boost possibly a stuck N75 most likely not directing boost to the WG.
Tried moving the wastegate and found that it runs off pressure instead of vacuum. So I blew in it with my air hose and it moves fine. Took out N75 to look for carbon buildup and found none. Lines are clear. Going to research which solenoid under intake makes the pressure go through to the N75. Where does it get it's pressure from? Air pump? Or only when boost is going through intake pipe back up to N75?
 
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Jack@European_Parts

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Boost comes out of the charge pipe than directed to the N75/switched by ecu to allow boost to commence to WG motor at turbo via duty cycle.

When not in use sends boost back to the inlet of intake boot to recycle the charge to turbo inlet.

Many don't realize this but the N75 has a calibration slotted screw at top which can be set to compensate.

Be advised:
It should not be altered unless it is determined it is the item which is bad........... before experimenting.
 
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   #23  

Dana

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Is the MAF and air induction system (Airbox and related connections) OE? Aftermarket intake systems can cause problems but even on a vehicle with factory equipment a faulty MAF can cause false knock faults. That may be pretty rare but I experienced this in 3 or possibility 4 1.8T Golf based cars over the years.

If you haven't done so already I would drive it without the MAF to see if the performance problems are still present. Also, see if Basic Settings groups 028 and 107 pass or fail with everything connected and fault codes cleared.



Edit, I missed this one:
17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
P1297 - 35-10 - - Intermittent

Readiness: 0000 0001
I would still check the MAF and mentioned BS groups but absolutely agree with Jack here. Faulty PCV (easy to find if the oil cap is sucked on at idle), faulty DV including hoses to/from it and the solenoid or an actual turbo/WG issue are more likely.
 
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vdubdezl

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ok Jack and Dana. I tried checking the N75 when I got home. Checked good with 32 ohms per the spec from my Hanes manual of 25-35 ohms. Well, electronically good. Also forgot to mention that I used a hood prop at work and reved it up to 3000rpm at work. The wastegate stays all the way back(towards driver side) when reved up or engine off.
Dana- it does have aftermarket crap Spectre filter and chrome pipe.I tried cleaning the MAF and also driving with it unplugged. No change with either. I got the knock code off when I repaired the wires. So far, so good on that.
 
   #25  

Jack@European_Parts

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Sounds like a bad DV and a possible bad N75 mechanically.

Have you checked the ability to blow through when switched via outputs in VCDS?

0x01-03 GO!

You will require stored vacuum or simulated with mighty-vac for the DV to lift the valve.

Check for positive seal as well as release.
 
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vdubdezl

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Sounds like a bad DV and a possible bad N75 mechanically.

Have you checked the ability to blow through when switched via outputs in VCDS?

0x01-03 GO!

You will require stored vacuum or simulated with mighty-vac for the DV to lift the valve.

Check for positive seal as well as release.
Nope. Haven't tried that yet Jack but hoping to have some time tomorrow to run some more of it down. You really seem to have a great deal of knowledge on how to use this software to its full potential. Thanks again for all of your help. I have been researching all over and put posts on several other websites trying to find a solution. Hopefully soon!
 
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vdubdezl

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I checked it out Saturday and I believe the n75 might be bad. I used a Mightvac on it but it won't hold vacuum. So I put vacuum on it and it would switch between 10" vacuum and 0 while running the output test. I was blowing through it and didn't really notice a change in pressure even though I saw it on the gauge. Is this right?? On another note, just for the heck of it, I replaced the cat just because I had an extra one and no change.
 
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Jack@European_Parts

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The valve seals during duty cycle so most likely ok and you confirmed a swap....

What is the status of the diverter valve? ( This is most likely )
 
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vdubdezl

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The valve seals during duty cycle so most likely ok and you confirmed a swap....

What is the status of the diverter valve? ( This is most likely )
Diverter valve is good. I blew through it with no leakage and will hold 15-20" vacuum no problem for a while. Tried many times. No sticking. Appears to be sealing well. I'm really running out of ideas.
 
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Jack@European_Parts

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Torn boot or bad connector maybe faulty damaged intercooler or even map sensor contaminated or MAF faulty.
Could also be mechanical fail of turbo waste-gate valve internal could be cracked/broken.
 
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vdubdezl

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Torn boot or bad connector maybe faulty damaged intercooler or even map sensor contaminated or MAF faulty.
Could also be mechanical fail of turbo waste-gate valve internal could be cracked/broken.
I am going to pressurize it tomorrow again and just make sure. I have not removed the map sensor to check it so might give that a whirl also. Why did VW make the 1.8T system more complicated than the 1.9TDI system? I have had 2 of them. Just seems easier to diagnose a problem on those.
 
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Don't forget that the turbo charger could be damaged or the waste-gate could be an issue...... sometimes a weak spring..... not just the valve seal inside manifold outlet of the waste-gate.

In one case I saw the weld break at the arm ( Hairline crack ) to shaft showing a waste-gate operate when looking to appear externally correct, however, the valve inside the turbo lay open.
 
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vdubdezl

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I had to replace the exhaust gasket and looked at the flap in the turbo and it's fine. I pressurized it again and found the clip for the turbo outlet house in the wrong place causing the hose to leak under max boost. So I realigned that and got the hose back in. It had more power, but still had the shaking. I replaced the cat and still had the same symptom. So I am about to pull my hair and decided to take it to a friend that owns a garage. He had a VW guy there who checked everything and said I had the engine was running perfect. He checked plugs and even compression. He then drove it and decided it was a cv axle. Got the front end guy to drive it also and he said the same thing. They put it on a lift and the LH CV axle has play in it even though it looks brand new. They said that when it gets under torque is when you would feel it. You can push the clutch in and it goes away. I'll save up to get one and then try that. I'm a diesel truck mechanic and even I suffer from tunnel vision. I really hope this is it. Thanks again for all your help.
 
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