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Discussion Starter #1
I just bought a 98 beetle tdi and I believe that I may have gotten the shorter end of the stick. I cannot hear the turbo and I do not feel any power. I also get into limp mode after trying to accelerate in 5th on the highway. I checked with my Vag-Com and saw that I have the intake manifold pressure difference code along with the glow plug monitoring-intermittent. I know that the intake manifold pressure difference has to do with either a vacuum leak or a bad N75. I will check these after I confirm that the turbo is good.

My question is, how do I check if the turbo is good or not? Can I do anything with my Vag-Com? Is there any other reason why I am not getting any boost? Should I still drive the car with a bad turbo?

On another note, there's a good amount of rust on the rocker panels. Are they part of the frame on the beetle or just for aesthetics?

Thanks for your help guys!
 

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As long as the boost pipes aren't full of oil then the turbo should be fine, a little bit is normal, also the oil level will drop a lot if the turbo is knackered, just go through the low power and limp mode faqs and maybe the actuator adjustment one, you'll get there, it's always some little thing but you just need to find it.:)

http://www.myturbodiesel.com/1000q/a4/a4-ALH-TDI-engine-index.htm

welcometomyturbodies
 

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Discussion Starter #3
Thanks for your reply, I will check the MAF tomorrow. The PO changed the oil right before he sold it to me so I don't know if there was a drop in oil level. He might have cleaned the boost pipes too. I really hope it's not the turbo. With the limited space in the engine bay, I imagine it would be hard to replace it.
 

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You can just pop off one of the boost pipes at the bottom where they connect to the intercooler if you're worried, if it's the turbo there'll be to much pouring out to clean up lol. I think you'll probably find that it's the maf or sticking turbo vanes, vacuum leak etc though and not so bad as you think.:)
 

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Discussion Starter #5
I did the MAF test to see if it is good or bad and came up with these:

Full Throttle:


Driving:


From the FAQ, the results mean that I have a bad MAF. Could any other thing cause this?
 

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The driving looks fine.

One note about the full throttle chart is that you can't tell from the chart how hard and how fast you're pressing the throttle pedal. If you press suddenly there will be a small lag in the boost and MAF. Judging by how steep the green line is, I'm guessing you press hard and fast. However, if you hold the pedal, the MAF actual should still climb to meet it.

A clogged cat or other mechanical problems like a bad turbo could cause the symptoms you see, but due to how common bad MAFs are and based off the fact that it's cheaper/much easier/faster to replace the MAF than the turbo, it's a safe bet that replacing the MAF will help the problems. However, bad MAFs don't normally cause limp mode. Please post a follow up if you change the MAF and please look at the other causes of limp mode/lower power FAQ articles because it could be something as simple as a bad turbo actuator or vac line.
 

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Discussion Starter #7
Thanks for your response. I just ordered a MAF from a guy in TDIclub and will post here if replacing the MAF fixes the problem. If that doesn't solve the boost issue, I would think that at the very least the vanes are stuck and it gets worse from there I guess. Oh well, maybe I can upgrade to VNT17 or something if it is blown.
 

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Yip and bigger nozzles and a tune. You'll soon hit 200bhp and need a new clutch and a smf lol. It's good fun though:D
 

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Discussion Starter #9
So the new MAF came in, I installed it and the readings are much better i.e. the same specified and actual reading-at idle at least. Before it would be way off. However, I still can't hear the turbo. I guess I'll have to go in deeper and check the actuator. Is taking off the turbo the only way to see if the vanes are stuck? Can I get it free without taking the turbo out?
 

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So the new MAF came in, I installed it and the readings are much better i.e. the same specified and actual reading-at idle at least. Before it would be way off. However, I still can't hear the turbo. I guess I'll have to go in deeper and check the actuator. Is taking off the turbo the only way to see if the vanes are stuck? Can I get it free without taking the turbo out?
Read the VNT actuator adjustment article. Basically, if you separate its rod from the lever that moves the vanes inside the turbo, you can isolate any actuator issue from an internal turbo issue.
 

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Discussion Starter #11
Thanks again. I did a real test of the new MAF on the highway and the specified and actual readings are way off, similar to the old MAF. The actual value would not go over 500 either. I read the MAF FAQ and it seems like it could be a clogged intake or EGR.
 

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Discussion Starter #12
I have add that I also checked the boost (meas. blk. #11) and the max actual value was 1200. I don't think that's normal.
 

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Someone else had this problem and it was a clogged catalytic converter. Some other possibilities: EGR malfunction which is recirculating air through the EGR and displacing the intake air. You can test this by making a small metal block off gasket and slipping it on the EGR exhaust tube where the gasket is now. It'll throw some codes but it'll rule out the EGR. Assuming it's not a turbo problem or ECU problem (impossible to diagnose without replacing the ECU), the cat is the only thing left assuming you have double checked everything else.
 

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Excact codes?

I have add that I also checked the boost (meas. blk. #11) and the max actual value was 1200. I don't think that's normal.
This was way off the specified value? (for VNT15 I think 1900-2000 is max specified). I would bet that the vnt actuator is compleatly stuck in 'no vacuum' possision (minimum boost) for this to be possible. You can try to exercise the vnt actuator rod with the engine off (see picture #6 in this thread).

If you are able to move the vnt actuator by 'hand', then check that it moves when you fire up the engine. The best way is to get someone else to start the engine while you look at the vnt actuator (on my ALH tdi you can see this without removing anything, but its easyer if you remove the engine top cover plate)

When you starte the engine and have a VNT-turbo, the ECU will apply full vacuum (full boost 'possision'). So if the vnt actuator is moveable by hand and stil dosnt move when you start the car:
1: Check if you have any vacuum at all (use your finger)
2: Check for vacuum leaks
3: Inspect / replace N75 valve (Boost pressure control, its the one that has a vacuumline from the N75 to the vacuum actuator on the turbo)

Can you post the excact error code that you read with your vagcom?
 

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Discussion Starter #15
I just noticed that after installing the new MAF, the car loss more power. What more is that the MAF did not fit correctly with the connector: the grooves are different. I have been pushing so hard to get it to click and it wouldn't and now the connector is broken. Swapped the old MAF and got the power I used to have albeit not the power it suppose to have.

Moving on, I removed the intercooler to EGR hose and intake to turbo hose to get to the actuator. I tried to push the rod down and up but it didn't budge. I removed the "outer" 10mm bolt that's holding the actuator but could not remove the "inner" one since it is badly corroded and just stripped. Any tips on how to remove the actuator or maybe just ? It's really tight in there and I have almost no space from the top. I can't even see the bolt and only working by feel.

My codes are:
00575 - Intake Manifold Pressure: Control Difference (causes limp mode)
Glow Plug Monitoring Intermittent
 

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Discussion Starter #16
O, I also pushed on the turbo shaft just to see if my turbo is blown or not and fortunately it did not move a all. No horizontal or vertical or side to side play and it spun freely. Is it possible to remove the turbo from below the car? Is there any space or stripped bolt issue?
 

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Possible but there are space issues.

Did you get the actuator off? There is an article in the FAQ just for VNT actuator checking. The rod should move down against a spring and spring back up easily with no binding.

And the new MAF must have been wrong because it should have fit fine.
 

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Discussion Starter #18
I could not get the actuator off because I was unable to remove the 10mm nut that is towards the front of the car since it is badly corroded and stripped. I also could not turn the locknut from above to adjust rod length and maybe move the VNT lever.
 

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Discussion Starter #19
Turbo!

Finally I got around to remove the EGR, Intake manifold and finally the turbo. With the intake out I saw that it was 80% clogged. I removed what I can with a flathead and brake cleaner and then soaked it with paint stripper. After 2 hours of soaking, I washed it with a pressure washer and brake cleaner and it was so much better. I did all of this while waiting for PB blaster to soak the turbo housing. Unfortunately, we couldn't get the housing and deemed that it has fused. My friend tried to free the vanes by moving the lever with a pry bay and managed to do so. After a few open up and down motion on the level it feels like the vanes are moving freely. I hesitantly put the turbo back on the car because I know that I should really have opened the turbo casing and clean the vanes but I just didn't see a way at that time.

My friend also made block off plates so EGR related parts can be removed. Hopefully it won't be a bad thing except for a CEL. I have to stress that it takes at least twice the time to fix the turbo on new beetles due to their limited engine space. It did take us the whole day but I am an amateur. I took it for a run today and I can finally hear the turbo spool. I can feel more power too of course. My concern now is that I can hear a grinding/rumbling sound when idling or driving that originates from the turbo side of the car. I have no idea why. I'm pretty sure everything was tightened down. Anyone have any input?

In retrospect, if I knew that the turbo would fuse, I would just concentrate on getting the actuator off and working the vanes until it is free. Taking the turbo off is pretty time consuming and if I have to go about it again, I will seriously consider upgrading. Lastly, thanks for help guys!
 

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:thumbsup

Blocking the EGR will increase warm up times because you don't have hot exhaust gases warming the coolant through the EGR cooler.

Prying on the turbo lever with a prybar is probably not a good thing...but it sounds like it's already seized. Hopefully if it grenades you will know to shut it off right away...

Time for a new turbo and a tune ?:nana2:
 
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