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Discussion Starter #1
New to the forum, but I need some advice. Just purchased a 2000 Jetta TDI, but the car feels slow. I have driven V8's for the last 20 years. Car starts and idles fine and it will rev over 4K on the road, but it seems to take a while getting up to speed. I disconnected the MAF and it ran a lot better, so I replaced the MAF with a Bosch rev C unit. Car is better, but still slow. I cannot hear the Turbo.

What is the baseline performance of this car? 0-60, 1/4 mile, etc... Right now 1/4 mile feels like 25 seconds and 0-60 is 15. Car is slow enough that I feel endangered driving in traffic.

Details: Rebuilt engine, new clutch, and rebuilt turbo. I will be replacing all the vacuum lines this weekend.

If car is in limp mode, can I get to 70 MPH, which the car will do. I cannot feel any boost from the turbo when driving.
 

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2nd on error codes. There's a vacuum line diagram under the hood. If the engine was rebuilt they could have mixed some lines up. I can hear and feel the turbo so something is wrong. Did you change the fuel filter and check the intake?
 

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Discussion Starter #4
Fuel filter is new. Checked vacuum hoses and they appear correct. However, the EGR hose is disconnected and the hose that goes to the N18 switch is blocked with a small bolt in the tube. Intake and exhaust plenums are clean, as these were tanked during the engine rebuild (according to the seller).

I have no black smoke under full acceleration, so it may also be starving for fuel. Additionally, I attached a vacuum pump to the hose off the N75 valve to the turbo actuator and it does not move at -25 psi vacuum. I can move it somewhat by hand, but it is difficult. It does not move the 1 cm quoted in the TDI site article. It moves about 3/16 of an inch.

Since it appears the variable vanes or actuator are not working and I do not know the "true " condition of the turbo I am just going to replace it.

The seller handed me receipts for all of the parts, but for the turbo, he had only purchased a cartridge kit. It may not be assembled correctly. I found a site that will sell the whole turbo assembly with the plenum and actuator for 500 dollars. They will then return 150 for the core.

I have noticed one additional item. The N75 valve is buzzing/vibrating loud enough to hear it in the car while driving. Is this caused by the bad turbo or does this mean that the N75 valve is bad also?

Thanks again for all your knowledge and advice.
 

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Discussion Starter #5
Additional information. This is the reply I just received from the seller.

Sorry you're having problems. The turbo is new from e-miatta.
The vnt was taken apart and completely cleaned, it had quite a
bit of carbon build-up but was in good shape. You can unhook
the actuator arm and the lever should move. If not then it's
probably stuck for some reason. It might have some residual
debris from the cleaning wedged in it. There's a vw forum that
walks you thru the cleaning process. It's not a real big job and
the bolts should all come off pretty easily. That sounds like the
problem area to me. The VNT is in good shape and shouldn't
require anything more than an adjustment or realignment. I'm
also not ruling the fact that it might have been put together
wrong. Before you start the job I recommend you invest in some
metric allen-wrench sockets and hose clamp removal pliers.
They will make the job go by much faster.
The intake, egr, and head was cleaned at the speed shop. They
had a lot of carbon build up as well. The EGR was disabled so
that should not be an issue. The intercooler was also taken out
and completely cleaned.
You can also go to Ross-Tech.com and download the vagcom
software for free. You will need an interface for the obd port
which you can find off ebay for around 20 bucks. It would also
let you reset any error codes and adjust the egr settings.
Good luck, these cars are a little tricky but once you get them
figured out they'er great little cars and easy to maintain. I would
guess the problem is with the VNT adjustment.
 

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E-miata stuff is crap. Toss it out before it blows up and takes the engine with it. It's all made in China with low grade materials. If the turbo VNT lever can't move it's bad. While you can use an ebay vag com cable, I don't know if it can do all the good stuff. Check the fuel injection quantity to see how much fuel is getting injected. Search for IQ or hammer mod.

The way the N75 controls the turbo is by rapidly opening and closing boost until the turbo makes the target boost. That's probably what you are hearing. If you touch it, you should be able to see if it's what's vibrating.
 

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First put everything back to stock so you can figure out what's working and what's not.

It's possible the previous owner blocked off the EGR when he said it was disabled. Look for a block off plate. If it's off, it'll throw a MAF code because the car's computer is expecting to see a certain amount of intake air and EGR gasses.

Many people report that adjusting the EGR using the adaptation through vag com will result in lower mpg on your car. The problem is that it's in the FAQ on another TDI site and it's wrong for emissions legal operation and wrong because the car's computer reacts.

There's nothing wrong with a new cartrige rebuild but it sounds bad, especially if it's from that seller. Take off the turbo and tell the previous owner to send it back and split the refund with you. IMHO, the products by that seller are of very low quality. It figures that it sounds like it's already broken. While there are OEM Chinese VW parts, my best belief is that the ones he sources are the poorly fitting copycat parts. A few reputable vendors include (all .com)
kermatdi
worldimpex
idparts
boraparts
ecstuning
mjmautohaus
and of course, the dealer.

I forget if it's in the article but you can temp swap the EGR and N75 turbo solenoid to test them.

Oh, and if the previous owner put on a new timing belt from that crappy seller, get it off ASAP. It could work but I have read many reports of failure.
 

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Discussion Starter #8
OK, I will get the timing belt replaced ASAP and the turbo. I looked a idparts.com and they sell a garret turbo that is the VNT17. Is this worth doing? Does it cause problems? I do not want to reprogram the ECU.

Is there a benefit of getting a VNT17 versus the VNT15? Remanufactured or new?

Obviously, I want to spend as little as possible.

Everyone seems to concur that e-miata is a load. I guess the old axiom is true, you get what you pay for.
 

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Discussion Starter #9
There is a local upullandpay lot here. There is a 99 passat wagon there, but they are all gas. Does that use the same vnt15 turbo? I could get an oem turbo a lot cheaper and clean it, versus spending 1K plus. Thoughts?
 

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Nope, different housings and the gas ones aren't VNT. The VNT won't do anything if the tune isn't changed too. Bigger nozzles + the VNT 17 and a tune = :D
 

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Take a look through the turbocharging FAQ and basic performance FAQ articles.

The VNT 17 turbo will lag a little more because it's bigger but it can support more power. A good chip tune will remove any lag though, and give you more power. By this mileage you could use new nozzles. I'd go with +1 size nozzles at a minimum. http://www.myturbodiesel.com/1000q/tditurbo.htm Take a look at this for a chart of turbos. As a rough estimate, you can get up to about 150 hp which is 60% more than stock. The torque will also go up considerably. Past that point you have to look to other upgrades like bigger fuel pumps.

You will really like the car. You'll probably need a new clutch but the early cars had stronger clutches.
 

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Discussion Starter #12
Turns out it is the turbo actuator that is faulty. I know now that the seller in North Carolina of TDI parts sells junk, but I believe that I should replace the timing belt (800 dollars?) and probably fix the turbo for now. The e-miata part of the turbo is the cartridge, with the original housing. I assume it is chinese bearings as well. If the turbo goes, can I believe that it will not cause engine damage, whereas, the timing belt lets loose = new engine.
 

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If the turbo fails it could cause damage. A few possibilities:

It breaks and the engine shuts down without damage. Clean out the shrapel. Big pieces won't make it past the intercooler but you have to thoroughly clean out the entire intake path to remove any metal dust.

The bearings fail and because it's under oil pressure, oil goes out the exhaust and causes massive smoke with low chance of damage. AND/OR
the oil goes into the intake side and causes the engine to runaway. Read here: http://www.myturbodiesel.com/1000q/stop-runaway-diesel-engine-how-to.htm

It breaks and all that oil hydrolocks the engine instead of running away. Or the diesel engine runs away and hydrolocks.
 

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What about a clogged cat? I second the statements on the crappy parts. E-miata is only one of the names this guy hides under, so be cautious. Good luck.
 
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