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Discussion Starter #1
I have a 1997/98 late 97 production date? On my turbo there are two what seem to be vacuum lines? One [red coated] is producing air the other [blue coated] does nothing or it seems. The blue one goes to the actuator. Should I have a positve vacuum in this line? Both lines come from a n75? as I am not sure. There are three lines total to the unit and two wires. The third line goes in front of the the maf feeding the turbo. I have a lack of turbo pressure at high rpms. All vacuum lines are good and sensors all seem to be functioning. Any ideas???
 

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I forget which line does what but if the blue line goes to the wastegate can it should be producing pressure when boost is maxed out. The air pressure moves the wastegate can arm which opens the wastegate. there should be a vacuum diagram under teh hood.

Have you checked the vacuum line inside the turbo? http://www.myturbodiesel.com/1000q/a3b4/ecu-hose-chip-tdi-65535.htm It normally causes a CEL/MIL. any error codes? Check out the FAQ articles for a low power troubleshooting article. I don't know if your turbo is cutting out but if turning the car off-on resets it, it's limp mode.
 

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Discussion Starter #3
re lack of turbo pressure

I have checked the ecu line aswell. All are in good condition and hold vacuum without a drop in pressure. The blue line the actuates the waste gate has no vacuum throughout rpm range. From what i can find on the web it should need vacuum to keep the gate closed to build pressure. Kind of mixed up on that because my gate open in the opposit of what they are showing. I know it is because of the brand of turbo. They also say when there is no boost the wastegate rod should be extended. Mine is not. When i use a screwdriver to push on the rod, it will move forward [towards the drivers side] and the spring returns it. Should that be?
 

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re lack of turbo pressure

I have checked the ecu line aswell. All are in good condition and hold vacuum without a drop in pressure. The blue line the actuates the waste gate has no vacuum throughout rpm range. From what i can find on the web it should need vacuum to keep the gate closed to build pressure. Kind of mixed up on that because my gate open in the opposit of what they are showing. I know it is because of the brand of turbo. They also say when there is no boost the wastegate rod should be extended. Mine is not. When i use a screwdriver to push on the rod, it will move forward [towards the drivers side] and the spring returns it. Should that be?
 

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So is your turbo a wastegate turbo and not a vnt? If it's a wastegate turbo then it only opens the wastegate when the turbo has reached it's limit on boost, it only opens to release excess pressure and prevent overboost but if you have the vnt then it requires vacuum to actually increase boost and if there's a problem with that then you will lack boost. Have you scanned for fault codes? My neighbour is currently having a similar problem but it's the maf that is causing the problem.:)
 

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Discussion Starter #6
It is as far as I know a vnt oem turbo. None of the line going to the turbo have a possitive vacuum. One of the line blows air at you instead. And what i thought was supose to apply vacuum to the vnt does not have vacuum. None ot the pictures or vacuum diagrams i have seen match my system. all i can say is that on the passenger side fender well is a 12 volt unit with three hoses and two wires. It clicks when the car is running and shuts off if you unplug it. to reset you have start the car over again. None of witch improve my pressure. Have replaced the maf.
 

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We need to try and think about these vacuum lines in a bit of a logical way, first there should be suction going to the n75, then it should go from there to the actuator on the turbo, I can't remember where the the one to the ecu comes from but it has to be able to measure the pressure because I think the map sensor is contained in the ecu. Check for suction at the n75 first then post back.:)
 

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For a US spec car, there's no way you have a VNT OEM from the factory, not on a 97 Jetta, unless someone modified it.

The line to the wastegate blows air when the boost max is reached. The pressure opens the wastegate can and door. That is why the rod is not extended.

Also, post merged so that it's all in 1 place.
 

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We need a good faq on the waste gate turbo because there seems to be some still knocking about including mine.:)
 

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I'll look into it, I'm also not sure my wastegate works the same way as your guys, I was fairly sure mine was a suction job to release the boost but I'll double check, there should be enough info knocking about on the interweb to put something together.:)
 

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Discussion Starter #12
lack of turbo pressure. So I started my car this morning. Had all my turbo there. But when I shut it off to get fuel it reset back to lack of pressure. When it starts up warm it will go to 2000 rpms and drop back to idle. So at lunch I checked it again and had turbo pressure but again failed after starting it warm. Could it be my 12 volt fuel solenoid on the injector pump? Have had this problem with my 6.2 diesel. And can you tell me if there is a pickup pump in the tank. Or if the injector pump is the only one?
 

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The fuel pickup in tank is only sender. The IP is the only thing that moves fuel on the engine. The 12v fuel shutoff solenoid is on-off and the hole is pretty small. What were the symptoms of the fuel shutoff failure on your 6.2 diesel?

Also, you keep posting in other threads. Please post in the mk3 section in your thread so that all your posts relating to this topic are in one place. It's hard for people to keep track of a problem if you post all over the place. Thank you.
 

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Discussion Starter #14
Well with the 6.2 . When the solenoid went bad it would intermitently allow fuel to flow and when it quit it wouldnt at all. This would only happen when it was hot. Always would start when cold. As for the tdi Im not sure I opened the waste gate several times manually. Dont know if that helped. But still is dumb founding that it reverts back when I shut it off and restart it. Thats what leeds me back to the fuel issue. I dont hear or see a boost leek.
 

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Maybe it's nothing to do with the turbo on your car, I've not heard of the turbo causing these problems that you're having, it sounds more fuel related. I don't think it's the solonoid as the car starts and runs ok but the revving up to 2000rpm then settling back down doesn't sound right. What sort of milage is your car and have you scanned for fault codes yet? It really is the best place to start imo and I think it would save you a lot of hassle. Turbo issues are usually when driving and the power suddenly drops off or comes and goes or you get limp mode where restarting the engine restores power but it sounds like you're having other things going on. Get the car scanned as soon as you can and post back with the results, you could try asking on here or the other big site if there is someone in your area who will scan it cheap if nothing else.:)
 

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Discussion Starter #17
Oh Yeah you asked how many miles. It has 104546 as of today. Timing belt was changed at 85k, just changed fuel and oil filters last weekend.
 
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