Volkswagen Passat Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
2,395 Posts
Discussion Starter · #1 ·
What are the following parts called, and what do they do on my AEB??? I'm trying to solve a throttle body position sensor error mystery. I found the following parts and I'm curious what the do, and if they could be causing my problems.

This looks like a sensor or something, located right behind my throttle body. It mounts to the intake manifold.


Are these a check valve of some sort? The outer plastic is dissolving, and the connections to the vacuum lines are not overly secure. The valve/hose connection is not tight enough, IMO.


This looks like an identical valve only it is right near the airbox and seems to be close to my MAFS. There is also a part nearby that has a vacuum connection and looks like it has an electrical connection to the MAFS.
 

·
Registered
Joined
·
432 Posts
The sensor is the intake air temperature sensor. Important to the ECU as 1 of the factors in calculating correct fuel mix.

Yes, I understand that those check valves are used in several places in the engine. You will need to replace them before they fail completely. You may buy them for a few dollars each. I saw them either on ECStuning or on Drewparts web sites.
 

·
Registered
Joined
·
2,395 Posts
Discussion Starter · #3 ·
thanks dread.

Does anyone know the part number of the vacuum check valves. I think I need a few of them...

Thanks. I'll check out ECS and Drewparts...

-Mark
 

·
Registered
Joined
·
2,395 Posts
Discussion Starter · #4 ·
Found both of the parts at www.impexfap.com
ECS had the check valve but didn't have the intake temp sensor. I wanted to order both from the same place in order to save on shipping.

The part numbers for my AEB are
058 905 291 - check valve - $10.72 each
058 905 379 - intake temp sensor - $35.12

I've been thinking that my idle problems may be linked to the intake temp sensor due to the fact that my idle is normally OK when the temps are moderate. During the winter and summer my idle wigs out.

The code that is thrown is always throttle body position sensor related. I'm on my second TB and I always readapt the TB with a VAG whenever I disconnect the battery, or perform intake work.

While poking around under the intake manifold I noticed that the check valves look really bad. The outer plastic is bad and the check valve fittings are not making a good connection on each of their hoses. Replacing them can't hurt. I'll replace the one time use clamps with some corbin clamps or something.

Also, I noticed one of these check valves near the airbox. I'm wondering if these bad connections may be causing the MAFS to give an OK reading, but then screw up the TB in some way down the line.

I guess if this doesn't fix the problem, I'm back at square one.

The big problem with me is that the TB codes are causing the A/C compressor to turn off and on due to the load varying. If the load decreases, the A/C turns on, when the idle is out of spec, it shuts the compressor off and blows warm air. Yuck!

Thanks again Dread.

-Mark

I've never had boost problems when the idle problem is happening. But I do get boost pulsating and the vacuum is "notchy" when I turn the car off.

-Mark
 

·
Registered
Joined
·
3,946 Posts
Mark those valves are imprtant because they are only one way. It means that they let air one way and prevent it from going back. If they don't seal you will have problem with the whole vacuum system. That may be your problem with the idle.
 

·
Registered
Joined
·
2,395 Posts
Discussion Starter · #6 ·
Yeah, I'm trying to figure out the following....

If there is a vacuum leak, why is it showing up as a TB code, instead of an A/F ratio DTC or something similar??

-Mark
 

·
Registered
Joined
·
1,482 Posts
Mark, have you upgraded you hoses yet? There are plenty of kits with tons of Silicone hoses in various sizes. For the smallest ones 3mm or 4mm works fine. Some info I think in the info forum. Some of mine disinegrated months ago. Went to Pep Boys and grabbed a $12 kit (Red or Blue or Yello) and worked great.
 

·
Registered
Joined
·
2,395 Posts
Discussion Starter · #8 ·
I've replaced the FPR and DV hoses multiple times. Its the hoses under the intake manifold and near the airbox that I'm concerned about. :)

-Mark
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top