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TDI 101 Got a simple/basic TDI question? Are you a newbie (new to the forums). Feel free to post your question here.

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Old February 7th, 2006, 04:05   #1
busyditch
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Default Turbo or clogged intake?

I have a 2000 Golf TDi with 80k miles. It has had a decreased amount of power recently, especially on hills. I have a suspicion that it is a clogged intake, but my friend/mechanic says he thinks its the turbo. I have a boost guage and the highest the boost gets is about 16.5 lbs. Is it possible the clogged intake will restrict the ability for the turbo's vanes to open completley for maximum boost? I plan on having the mechanic clean the intake soon. Should I go ahead and change the turbo while the engine is apart? Thanks to you all for your support.
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Old February 7th, 2006, 05:58   #2
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MAF sensor...You will need a VAG-Com to diagnose it.

Turbos don't go bad they grenade! No doubt you would notice that!

Most gasser mechanics have no clue how a TDI turbo works, turbos don't just stop producing boost.

There is a check you can do on the VNT ring to verify proper movement. This is perhaps the only situation where replacement of the turbo is warranted. However if the turbo is taken apart and cleaned it can be reinstalled with many miles remaining of useful life.

Again start at the MAF sensor or N75, also do you have a check engine light? If not this also point to a bad MAF sensor since a code willl NOT be triggered.

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Old February 7th, 2006, 07:09   #3
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I'd also say the intake with 80K. Seems to be the point I clean a LOT of them. Could be a combination of the two.
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Old February 7th, 2006, 07:43   #4
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My intake at 85k, you might want to clean yours along with replacing the MAF.

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Old February 7th, 2006, 09:12   #5
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Clean the intake while it's out.
Reaplce the MAF ($80).

It's probably not worth replacing the turbo at this point unless you really just want to spend the money.

Unless you see a cloud of white smoke in the rear view mirror and get 0 boost, you haven't destroyed the turbo yet...
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Old February 7th, 2006, 09:29   #6
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The key is "Reduced power recently". Intakes don't plug overnight, it takes thousands of miles and you will never detect it unless you drive another TDI and realize how aneamic your car is.

Maf sensors when they go bad cause the same symptoms as a clogged intake.

A plugged intake causes a narrowing of the passage way which reduces the volume of air entering the motor WITHOUT reducing the stock boost pressure which is in the area of 16.5 psi. The reduction in air volume also causes the maximum injection quantity to be reduced as well and this every so slowely causes power to drop off over the course of 50,000 miles. It occurs so slowely that you never detect it.

Get the MAF sensor checked by performing the load test as described in the Bentley manual along with using a VAG-Com. This is the only way to know exactly how the MAF sensor is doing.

IF the intake is in resonable shape don't let your average mechanic mess with it. THe reason is dropped carbon pieces or improper assembly of the components leading to a blown motor. Take it to somebody that has experience with EGR removal and de-coking. The intake can be cleaned without removing it from the car, the only thing that needs to be done is removing the EGR valve and scraping out the soot. It takes about 45 minutes and keeps you from turning this into a major project with all the power being restored as a side benefit.

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Old February 7th, 2006, 09:29   #7
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Start with the intake then check the maf after you did a cleaning. You would know for sure if it were the turbo
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Old February 7th, 2006, 09:49   #8
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Drivbiwire: How can yo clean the intake with it on the car without getting all that crap into the head?
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Old February 7th, 2006, 09:58   #9
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I had severe overboost problems with the clogged intake, now the highest it will go is 21. DBW you mentioned the maximum injection quantity being reduced, does this fix itself after cleaning or is there something I can do with vag-com?
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Old February 7th, 2006, 10:26   #10
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I second the info for a 45 min intake cleaning.? Our 00 Jetta has 171,000 miles and we are original owners. I know it is long past the need for an intake cleaning.
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Old February 7th, 2006, 10:54   #11
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I have made posts on this before. The simple part of it goes like this:

-Remove EGR

-Use a paint can opener, long rod with a 90 degree angle to scrape out the soot and pull it out the opening.


-Remove as much soot as possible (metal should be visible to bottom and sides) then,

-Cap off the EGR cooler outlet with a piece of metal

-Have somebody get in car and start it and keep rpms around 1500.

-Using a long flathead screw driver scrape away the rest of the small buildups which are easily passed through the motor and out the tailpipe

-Once the intake is scraped clean shut the motor off and put the EGR valve back on.

People freak out about soot getting down into the motor but they forget it happens all the time! You don't want large pieces falling in obviously, but small pieces are fine and easily passed on through and blown out the tailpipe the first time you get on the power.

Total time for this is around 45 minutes and accomplishes a complete intake cleaning.

As far as the ports go they don't get that much build up, the other thing is nobody ever gets the soot out of the head. The main restriction occurs at and just after the EGR valve, this is why VW made the valve removable so that you do not have to remove the entire intake manifold...They know this would happen on US spec high sulfur fuels.

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Old February 7th, 2006, 10:58   #12
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I cant imagine what yours looks like cody. What kind of mileage are you getting?
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Old February 7th, 2006, 11:06   #13
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45-47 mpg, last May got 52 and the motor had about 150,000. At around 100,000 I had the EGR disabled. Didn't start using diesel purge and klean until after 100K.
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Old February 7th, 2006, 11:14   #14
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MPG isnt too bad, disabling the EGR must have helped.
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Old February 7th, 2006, 11:19   #15
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I'd not recomend that procedure for the average joe though. Sometimes the carbon is not soft, powdery, or oily. Sometimes it's rock hard and that is the stuff that bends valves. That's what happened to the engine I helped rebuild this summer.
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