Oil Blow By and Overboost P0234

Have not heard back from my more recent posts. I get it that I post a lot about my Overboost. I have followed all suggestions and replaced many parts just to be sure. Still I have the Overboost. What is weird is that the steps i have taken, like yesterday installing new MAF, which did not solve the problem but seemed (how is this possible?) to "improve" the performance up a certain hill on Skyline Blvd Highway 35 San Francisco. I got several miles up a moderately steep incline running it above 30,000 RPM (the usual trigger) and was about to think i had solved the problem when suddenly there it was. I turned off and back on at traffic light and headed home. It took about 30 minutes of driving before losing the Turbo. Then I got the engine light too.
Anyway about the Oil Blow By. On Monday i finally figured out a way to get that third bolt out connecting the EGR to the Intake Manifold and looked inside, stuck my finger inside, using finger nail to scrape at surface. There was only a light sheen of a very black greasy substance, the same i saw in front of the flipper thing in the EGR (moves freely by the way) and then someone said that older TDIs have problems with oil blow by which made sense seeing the grease on the walls of the intake. Can Blow By cause Overboost? Or, is that a separate issue?
Thanks to anyone who replies
Michael Patrick San Francisco

that flipper thing is the anti shudder valve... it should not move freely... check the plastic actuator on the back of it to see if the rod has snapped - super common.

any chance that the ASV shutting momentarily or maybe just partially would cause a spike in intake pressure while not killing the engine before it reopens??? I dunno... but you still need that fixed if it is indeed snapped.

oily residue in the intake tract is normal. The crank case vent hockey puck thing is far from perfect in that regard. If you are concerned that it is too much oil in the intake side, open the lowest hose on the intercooler and see how much comes out. shotglasses is normal, beer cans is not.

watchingcrow said:

yesterday installing new MAF, which did not solve the problem but seemed (how is this possible?) to "improve" the performance up a certain hill on Skyline Blvd Highway 35 San Francisco. I got several miles up a moderately steep incline running it above 30,000 RPM (the usual trigger) and was about to think i had solved the problem when suddenly there it was. I turned off and back on at traffic light and headed home. It took about 30 minutes of driving before losing the Turbo. Then I got the engine light too.

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The new MAF is probably giving the ECU correct info which made it run better.

Are you sure you hit 'above 30,000 RPM'
How many states did the engine parts fall in?
(Sorry, couldn't resist)

Have you checked if the arm on the turbo moves freely?
You might have to take the actuator rod clip off to check it or the entire actuator. It's only 2 nuts & a vacuum hose.
If the arm sticks and does not move the full range you may try working it back & forth full path for about 5 minutes. It's been posted to help free it.

It may be worth turning the actuator over and shake it to see if there's rust inside it. There is a VW bulletin about it.
Tie a piece of thread of floss to the clip so when you try to put it back on and it flies away it's easier to find.
There may be 2 or 3 clips hiding in mine somewhere.

Have you replaced the vacuum hoses for the entire boost function?
There should be one going to the bottom of the air filter box. Make sure the hole in the box is open.

wonneber said:

The new MAF is probably giving the ECU correct info which made it run better.
Are you sure you hit 'above 30,000 RPM'
How many states did the engine parts fall in?
(Sorry, couldn't resist)
Have you checked if the arm on the turbo moves freely?
You might have to take the actuator rod clip off to check it or the entire actuator. It's only 2 nuts & a vacuum hose.
If the arm sticks and does not move the full range you may try working it back & forth full path for about 5 minutes. It's been posted to help free it.
It may be worth turning the actuator over and shake it to see if there's rust inside it. There is a VW bulletin about it.
Tie a piece of thread of floss to the clip so when you try to put it back on and it flies away it's easier to find.
There may be 2 or 3 clips hiding in mine somewhere.
Have you replaced the vacuum hoses for the entire boost function?
There should be one going to the bottom of the air filter box. Make sure the hole in the box is open.

Click to expand...

HAHA 3,000 then - what is a zero among friends.
I have done all of the things you recommended (except checking the "hole" at the airfilter and more, using a Vacuum Pump to test the Actuator under the car which is virtually unreachable by me but the test came up very good.

Is there a DTC for the over-boost or are you observing a boost gauge? I must have missed your other threads.

Yeah, oil inside the intake system from the hockey puck thingy is normal. Note, a little oil inside those pipes doesn't translate to a lot. Your dipstick should tell you more about oil loss or usage.

3000 RPMs up to about 3600 RPMs is good boost range to keep the oil blown out of the Inter Cooler. Generally, boost will begin to drop off after 3400-3600 RPMs, depending on circumstances (which gear, incline, tune, etc.).

watchingcrow said:

HAHA 3,000 then - what is a zero among friends.
I have done all of the things you recommended (except checking the "hole" at the airfilter and more, using a Vacuum Pump to test the Actuator under the car which is virtually unreachable by me but the test came up very good.

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It sounds like you're not actually watching the actuator arm move, but just going by the vacuum guage.
You have to confirm with your eyeballs that the actuator starts moving around 3mmHg, and stops itself against the stop nub at around 18mmHg.
Forgive me but I'm skeptical your diagnostics are thorough.

Eyeballing Actuator

STDOUBT said:

It sounds like you're not actually watching the actuator arm move, but just going by the vacuum guage.
You have to confirm with your eyeballs that the actuator starts moving around 3mmHg, and stops itself against the stop nub at around 18mmHg.
Forgive me but I'm skeptical your diagnostics are thorough.

Click to expand...

I actually did watch the lever move in and out, and I was pretty certain it responded correctly at both ends of the spectrum. I was able to get 25mmHg and then stop pumping and it stayed there with no backsliding. What i did not do was measure it to see if it was at the correct "setting???"
I have done everything i can without removing it, which looks nearly impossible for a shade tree amature mechanic.

I do have one question, what does the Vacuum Reservoir do? It does not seem to be connected to anything other than that the vacuum hose leading to it. I checked the hose and tried the Vacuum Pump on that thing and could not get any pressure measurement, should it take and hold pressure?

"Forgive me but I'm skeptical your diagnostics are thorough."

I do not blame you for your skepticism as I am pretty much teaching myself/learning about this as I go. My major conclusion is why the hell is this so complicated? I mean there are hoses going everywhere and all these little things they are connected to. It seems like a Rube Goldberg device.

One answer i have maybe not given you is that i purchased and have used an OBD II Auto Code Scanner Automotive Diagnostic Scan Tool Check Car Engine Light Fault Codes Readers OBDII OBD2. But have yet to take it to my local mechanic to have him run the car by his more elaborated Scanner. He does not "do Diesel" but could give me a read out from that. Plus apparently the O'Reilly Auto Parts near me offers a service using their scanner too.

The vacuum reservoir is just that, a reservoir. Diesel engines don't "make" as much vacuum as a gassser, son we create a bit and store it for when needed.

watchingcrow said:

I actually did watch the lever move in and out, and I was pretty certain it responded correctly at both ends of the spectrum. I was able to get 25mmHg and then stop pumping and it stayed there with no backsliding. What i did not do was measure it to see if it was at the correct "setting???"
I have done everything i can without removing it, which looks nearly impossible for a shade tree amature mechanic.
I do have one question, what does the Vacuum Reservoir do? It does not seem to be connected to anything other than that the vacuum hose leading to it.
[some deleted]
I am pretty much teaching myself/learning about this as I go. My major conclusion is why the hell is this so complicated? I mean there are hoses going everywhere and all these little things they are connected to. It seems like a Rube Goldberg device.
[some deleted]
One answer i have maybe not given you is that i purchased and have used an OBD II Auto Code Scanner Automotive Diagnostic Scan Tool Check Car Engine Light Fault Codes Readers OBDII OBD2.

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OK, you saw the turbo arm move is good.
It should move the entire range and smoothly which would involve getting under the car. Not easy if you work on your back. Been there done that.

What do you mean by 'does not seem to be connected to anything other than that the vacuum hose leading to it'
It is a reservoir for vacuum as explained by BobinOH.
The hose leading from it should go to a tee which splits going to a one way valve and a vacuum solenoid. (Solenoid N75)

All of us were newbies at one time.
If can be frustrating until you learn and to this day I am still learning.
I did retire recently btw and was not in the auto repair field for many years.
I learned the TDI ins and outs one repair at a time and still learn new things from the wizards in this forum.

If you think these engines are complicated you should look at the big over the road truck engines or the big construction engines.

Take it one step at a time, you will learn.

I would put a vacuum pump and gauge to the turbo actuator. It should just start to move at 3.5 to 5.0 "/hg. If not adjust the length of the rod.
Reading random values at the N75 and stuff as well as reading too much into the code can lead to confusion. The ECU is not real sophisticated.

watchingcrow said:

(edit)
I do have one question, what does the Vacuum Reservoir do? It does not seem to be connected to anything other than that the vacuum hose leading to it. I checked the hose and tried the Vacuum Pump on that thing and could not get any pressure measurement, should it take and hold pressure?(edit)

Click to expand...

This could be a clue to a problem.
The vacuum reservoir should hold whatever vacuum that you apply to it.
Due to it's volume it may take a bit of pumping to get a reading, though.