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Discussion Starter · #1 ·
Took our new (to us) '02 1.8T Passat Wagon (56k miles) in for some warranty issues last week. I complained that the car sometimes stumbles when it first starts and seems to me to be a bit low on power in the lower RPMs (compared to our 98 1.8T Passat). Dealer charged $96 for an hour of diagnosis and reported a "dirty throttle body' that "needs cleaning" (for an add'l 2 hours of labor - total, $300).

Is this a known problem w/ Passats and/or 1.8Ts? Seems odd to me that anything would need cleaning of this nature after 2.5 years and only 56k miles. Also, convenient that the suggested fix is not covered under my CPO warranty ("it's a maintenance issue, sir"). Has anyone experienced similar problems (stumble at first idle, low on power in the 2-3k rpm range) and solved it by cleaning the throlle body? Any idea what causes this dirt or carbon build up (if that's even what it is)?

Thanks,
Tim
 

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I just cleaned my 2001.5 AWM throttle body last week for some rich at idle fuel trim issues. I am super slow/over careful doing home maintenance. It took about twice as long to clean as to remove and replace- total about 1 and a half hour (please no flaming for how slow I work). This is not a difficult job, since they have done your diagnosis for you. There are some DIY threads on this, just do a search for "throttle and clean". Especially with DBW engines like ours, some may say the door-open-key-in-ignition-engine-not-running trick won't work but it will work. I reset the throttle body this way and then checked it with VAG-COM and it was fine.
Do it yoursef, it'll save time and money and you'll be surprised by how easy it is if you have minimal mechanical ability.
Oh, I'm not sure EXACTLY what it is, but it's like laquer/carbonized stuff. I used Simple Green and a toothbrush to clean. I think they make a specific throttle body cleaner. Good luck and keep us posted.
Brad
 

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did the dealer do the cleaning already? if not, then you can do it yourself. very easy to do, especially on the DBW's. i used brake cleaner and the carbon came off easily. really, it's just removing 4 bolts. be sure to buy a new throttle body gasket (~$2 at the dealer), and you're good to go.

here's a pic of mine at around 40k. i'm the second owner, but i doubt the first owner ever cleaned it.



low power is normal below 3k, doesn't fully spool up until 3k.

if he pulls "it's a maintenance issue", pull out the owner's manual and check the maintenance section. it's not there. don't think it'd work, but go ahead and try that.

anyway, here's a detailed guide:

http://www.taligentx.com/passat/maintenance/throttlebody/

just disregard the stuff about the throttle cable.
 

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Like NotAPreppie said,
in addition-those are gases of oil from your valves that were not burned in the engine. They are comming back to cylinders, for second time for burning, via your air system,i.e. throttle body. It is mainly during cold start to faster heat up engine and lower polution.
 

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Discussion Starter · #6 ·
Thanks, All!

Wow, thanks everyone. This is exactly the info. I needed - and great instructions for how to DIY.

Few follow up questions:
1) does the gasket go on "dry" or is some type of sealant required?
2) What is a DB8 engine? I assume a code for the engine in my car, but can someone provide more details on this and other 1.8T engine codes? In particular, is there a different code for the 1.8T in our '98 Passat? What are the differences between these (and other?) 1.8T engines?
3) I had heard that by '01.5 the 1.8T had a "drive by wire" electronic throttle - is that true? (just curious)
 

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Re: Thanks, All!

tflacke said:
Wow, thanks everyone. This is exactly the info. I needed - and great instructions for how to DIY.

Few follow up questions:
1) does the gasket go on "dry" or is some type of sealant required?
Goes on dry..

2) What is a DB8 engine? I assume a code for the engine in my car, but can someone provide more details on this and other 1.8T engine codes? In particular, is there a different code for the 1.8T in our '98 Passat? What are the differences between these (and other?) 1.8T engines?
3) I had heard that by '01.5 the 1.8T had a "drive by wire" electronic throttle - is that true? (just curious)
I think you may have mis-read BD8 for DBW .. DBW stands for "drive by wire"..

Your 98 (AEB engine code iirc) passat has throttle that is mechanically acutated by your foot via a throttle cable therefore drive by cable.

The later cars are an e-gas setup where the throttle is electrioncally controlled via a potentiometer on the throttle pedal. (not sure of the engine code of those motors.. AWP possibly?)

sorry if im am telling you something you already know.. vodka makes my head fuzzy... :)
 

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TurboBrad said:
You don't necessarily need to replace the gasket, if integrity OK just reuse it.
yeah, but its cheap insurance.. spend two bucks and get the gasket and replace it while you have it apart or bolt it all back up together and have to pull it all apart later because you skimped on a 2 dollar gasket..
 

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Taking off the throttle body?

Newby owner with Passat but with other cars.... never removed the throttle body from the car to clean it. Just used throttle body cleaner in a spray can (with a small squirt straw), an old soft toothbrush (with a long handle), and lots of clean rags. Usually just hold the throttle open by hand to clean the backside of the butterfly and venturi area.

Is there some reason you can't clean the throttle body in-situ on the Passat?

Also concerned about having to use Vag-Com to reset the Throttle body after cleaning (don't have access to one). Does this happen every time?... Would it happen if you clean it but didn't remove? Afraid to clean it if I am going to have to take it to the dealer to get the codes reset.
 

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Re: Taking off the throttle body?

Dave99 said:
...Afraid to clean it if I am going to have to take it to the dealer to get the codes reset.
I cleaned mine a few weeks ago, didn't realign the throttle body, and the car didn't drive very well. I stalled whenever coming to a stop and throttle response was hokey...

I would highly recommend not cleaning your TB, unless you have access to a vag-com.

I'm sure some have gotten away with cleaning the TB and not realigning it, but it's up to you ultimately... If you go to the dealer they will charge you a ridiculous price to realign your TB.
 

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tflacke said:
Dealer charged $96 for an hour of diagnosis and reported a "dirty throttle body' that "needs cleaning" (for an add'l 2 hours of labor - total, $300).
30 seconds to diagnose + $3 in parts + 15 minutes of cleaning work = $396!!! :shock:

Please don't go back to that dealer. You got ripped.
 

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Re: Taking off the throttle body?

madigan said:
Dave99 said:
...Afraid to clean it if I am going to have to take it to the dealer to get the codes reset.
I cleaned mine a few weeks ago, didn't realign the throttle body, and the car didn't drive very well. I stalled whenever coming to a stop and throttle response was hokey...

I would highly recommend not cleaning your TB, unless you have access to a vag-com.

I'm sure some have gotten away with cleaning the TB and not realigning it, but it's up to you ultimately... If you go to the dealer they will charge you a ridiculous price to realign your TB.
Yes, not realigning throttle body can lead to serious driveability issues.
But as in original post, tflacke drives an 02, AWM, which is DBW.
The TB realign on this engine takes three minutes, no VAG-COM required.
There should be no DTC stored from this proceedure.
Well, anywhich way you choose, good luck.
Brad
 
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