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VR5 2.3 - Unpluged vacuum Line / Power loss when hot at 4000 rpm

11K views 62 replies 4 participants last post by  PZ 
#1 ·
Hello All,

If you have read my presentation, I'm french, so sorry for my poor english with mechanical terms.

Model:
PASSAT 3B5 - 2.3 VR5 Variant (Break Model) - 1999
F 3B-X-132 001>> * AGZ

I need your help. One of my vaccum line is not connected and i discover her during my cleaning.
On the technical manual, it should be plugged into the vacuum tank... but my vaccum tank est already connected with a line wich go in the car.

The vacuum tank for engine is the blue tank in the right of the engine ?

I drop 2 pics, I hope you can understand what i'm trying to say...
It's the line 44 / 45 / 46 on the diagram and I don't find the part 23 (bubble look ?), I have just the big blue tank.
Maybe if someone have pics for this lines ?

Motor vehicle Automotive fuel system Automotive design Automotive air manifold Auto part
Motor vehicle Automotive fuel system Car Automotive air manifold Auto part
Product Motor vehicle Automotive lighting Font Automotive exterior


Lot of thanks for your help,
David
 
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#56 ·
Before buy lot of thing (maybe useless)
I used the VCDS test function on the engine ECU.

It turns out that all tests are conclusive except 2.

Gas recirculation: ok
Heating Lambda probe: ok
Lambda probe: ok
Air conditioning: ok
Secondary Air Injection: FAILURE
Evaporative Emissions: ok
Heating Catalyst: ok
Catalyst: FAILURE

What to think of these 2 failed tests?
My first question: does my car have sensors to test the catalyst and secondary air injection?

Still no error codes on the ECU
 
#57 ·
The 1st O2 sensor checks the SAIP and the 2nd checks the CAT. When the SAIP runs, it pumps extra air into the exhaust and the ECU pumps extra fuel into the engine. This heats up the primary cat faster.

Is it possible you have the wiring for the 2 sensors swapped? That would screw up the air/fuel mixture. They are usally color coded from the factory, but replacements may not match.
 
#58 · (Edited)
I think there is a serious clue here.

Indeed, the secondary air pump does not start at cold start (I found a completely broken hose).
However, during the VCDS "actuator" test, the pump runs fine.

This would mean that the ECU does not tell it to start for a cold starting.

I can't identify these sensors you're talking about.
The one that checks the CAT is the Lambda? If so, it is correctly detected and connected (and new).
Where should she be the SAIP sensor ?

When I test my EGR valve with a vacuum pump, I have resistance to pressure and suction. So is she OK?
I also hear a little "TAC" noise, the valve must be activated.

EDIT : SAIP is working again since I repaired the hoses. I will do a test today.
For my science, what produces vacuum on VR6 / V6 engines (VR5 is just a VR6 with one cylinder less)
 
#59 ·
It has to be cold enough for the SAIP to activate. I don't know the exact temp range. I rarely heard mine run as it was often too warm here, even overnight.

The pistons moving down with the intake valve open is what creates vacuum. Later models added an electrical vacuum pump, usually near the ABS pump.
 
#61 ·
The SAIP is triggered by the ECU reading the temp sensor. Not sure if it's the outside temp sensor (in front of the bottom of the radiator) or the coolant temp sensor.
 
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#62 ·
New day, new tests!

And I was also able to put the car on a pit and inspected underneath.
I saw a drop of water at my manifold, I found a small air leak on a weld ... Could this disturb the values of the lambda? The hole just before the probe.
I also changed the way I drive, pushing the engine before 90 ° and it has the same symptoms. The heat would not necessarily be a factor.


However, SAIP still does not start cold. It only starts when I have "opened" the EGR before starting with a vacuum pump.

Ideas ?
 
#63 ·
Yes, the air leak can screw with the O2 values. The SAIP startup and valve opening should be at the same time. Is the valve getting vacuum at startup that is too low or none at all. The valve opening should not control the SAIP pump. It should be commanded by the ECU. The vacuum source should be backed up by the vacuum reservoir, so that might be why the valve opening is delayed.
 
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