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2003 Jetta TDI w/ ~150,000 miles. My car is in server limp mode, the RPM will not go above 2000 even in neutral. I have engine codes about EGR excessive flow and a couple of bad glow plugs. I checked the EGR valve and it seems clean enough and the valve seems to open and close fairly easily. I've replaced the MAF, the fuel filter, and the horrible K&N air filter. I have not had a much time to drive it with the replacement parts, but it is still sluggish off the start. I'm going to double/triple check that everything is tight and there are no leaks, is there any thing else I should be checking? Thanks in advance.
 

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Do a boost leak check, it sounds like a major one. I've had a hose pop off and the engine bucks and doesn't want to rev up. But in my case, it did rev higher, the engine just didn't want to.
http://www.myturbodiesel.com/1000q_how_to/multi/boostleaks.htm here is how to do it. Bad glow plugs are unrelated to low power.

If it's not that, please post some follow up tests. There could be an injection pump problem but that should throw error codes. It's not engine mechanical because the car should have trouble starting. It's also possible fuel is gelling or the fuel pickup at the fuel tank is clogged/gelled.
 

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I did have some problem removing the MAF connector from the old MAF. I did the test where I disconnected the MAF and nothing changed so I replaced it. A few months ago I had a code related to the throttle sensor, but it didn't show up the last time I had the codes read. I will stop by Autozone and have the codes checked again since I've replaced a few things. I'll be back! Thanks again, this site rocks!!!
 

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Sounds like the accelerator pedal to me. Our 2000 Jetta TDI was cruising down the highway one day when it lost all power. I could only get it to pretty much idle. We did check it for fault codes and got one relating to the accelerator position sensor. A new sensor did the trick. If the switch isn't working fully it only gives you a very small range of throttle position since it doesn't want to hurt anything (such as emissions components).
 

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Car starts fine with no problems. Error codes as read by AutoZone; P0402,EGR system fault (exhaust gas recirculation)- ECM has detected too much flow on the EGR system. Had this same code before I replaced the previous mentioned parts. New code since part switch; P0101, Mass or volume air flow sensor circuit range/performance-Air duct damaged. I also received an error code for my bad glow plugs. Will take care of those after I solve my no power issue first. I haven't had a chance to do a boost leak test but everything seems to be pointing to a major leak. Hopefully the weather is not too bad this weekend and I will try to change the hoses myself instead of paying a mechanic to do a boost leak test and tell me I have a leak. I will research the hose replacement process again, but any good tips will be greatly appreciated.
 
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Put a vacuum onto the line coming from the EGR solenoid and suck. This checks the EGR movement. Also try switching the EGR and N75 as a test. They can be swapped for testing to isolate the problem to one of the solenoids.
 

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Have not had a chance to do a boost leak test. Althought, upon visual inspection I didn't see or hear anything. I know it could be a small leak but with the codes I received I thought it was going to be fairly obvious. If there was a leak would the car run rough? The car is running smoothly and idles at ~900 RPMs. Since I'm going to have to pay to have it tested for the boost leak, I'm thinking of just replacing the hoses my self. I saw a diagram for MK3, is there one for the MK4? I know I need to replace one hose at a time but a diagram would be really helpful for me. Here's a newbie question:D, should I reuse the fabric that covers the current lines. I don't even know if it comes off but figured I'd ask now. With all that, I finally had a chance to drive it for an extended period over the weekend and added some fuel additives and injector cleaner and the car is running much better. It's still not 100%, but it is running much better. I'm wondering now if I'm having a throttle pedal sensor issue or a fuel pump issue. I say that because I have to push the pedal all the way to the floor to go. Plus, a few months ago I received an error code about the throttle pedal sensor but I no longer receive that code. Thanks again for this site and everyone who posts to it. You guys rock!
 

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If you have to pay to do a boost leak test replace the vac lines first since it's probably cheaper.

PM sent with the vac diagram. The fabric is part of the line and often frays off.
 
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