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Passat Variant B5.5 2001 manual 2.0L gas engine AZM 85kw
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Discussion Starter · #1 ·
Last October I got a 2001 Estate with a 2.0L AZM engine. Never had or fixed cars before, but just in case when I got the car I bought a VAG-COM from ebay.

A couple of weeks ago it started shaking at idle. I already had a CEL from SAIS before (since last year already), but when I connected the VAG-COM now I had misfires on all cylinders:

7 Faults Found:
17831 - Secondary Air Injection System: Bank 1: Insufficient Flow
P1423 - 35-00 - -
17549 - Load Calculation Cross Check: Implausible Value
P1141 - 35-10 - - - Intermittent
16685 - Cylinder 1 Misfire Detected
P0301 - 35-10 - - - Intermittent
16687 - Cylinder 3 Misfire Detected
P0303 - 35-10 - - - Intermittent
16688 - Cylinder 4 Misfire Detected
P0304 - 35-10 - - - Intermittent
16686 - Cylinder 2 Misfire Detected
P0302 - 35-10 - - - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
I cleared the codes and ran the engine again and got these codes:

7 Faults Found:
16687 - Cylinder 3 Misfire Detected
P0303 - 35-00 - -
16555 - Fuel Trim: System Too Lean: Bank 1
P0171 - 35-00 - -
16555 - Fuel Trim: System Too Lean: Bank 1
P0171 - 35-00 - -
16685 - Cylinder 1 Misfire Detected
P0301 - 35-00 - -
16688 - Cylinder 4 Misfire Detected
P0304 - 35-00 - -
16686 - Cylinder 2 Misfire Detected
P0302 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
I tried removing the MAF connector, still ran bad. I tried cleaning the throttle body and did a TBA, wasn't bad to begin with and ended up with this:
Auto part Vehicle Car Automotive lighting Engine


It didn't help, still shakes at idle. Here you can get an idea of how much it is misfiring (the fields with "count" count the misfires):
. It gets around 100 misfires in the first minute. Then from 1:30 on in the video I have the gas pedal pressed down a little bit (> 2000 rpm) and it has no misfires in the next 1.5 minutes.

Searching the forums a likely problem is a vacuum leak. I tried spraying carburetor cleaner around the hoses but couldn't find anything. So I made a smoke machine out of a pickle jar, some PVC tubing and epoxy glue, used charcoal and cardboard to make the smoke and found that it leaked a lot from around the connection point of this hose shown in the video:
(I don't show smoke in the video but I just show the place it came from, I can also do it with live smoke).

What is that connection? It is under the intake manifold as can be seen from the video. If I can find out what this is then I can try changing it out. Is it an EGR or PCV valve? (btw where are these on my engine?). When I tried spraying carburetor cleaner towards this connection, I didn't notice any change in engine speed (maybe because it is too far below the intake manifold and I couldn't spray on it good enough). Here is an overview of the engine compartment:
Land vehicle Vehicle Car Engine Auto part


The two big hoses running from the intake air passage to the engine and somewhere down didn't have clamps. I'm assuming they are some DIY hoses by the previous owner and I should add clamps to them? Here is a close up, I mean the two big hoses running from the junction with the three hoses in it:
Auto part Pipe Fuel line Metal Engine


But with the smoke test they didn't leak, it only leaked a little from the third smaller hose going to the right from the same junction (probably because I removed the clamp from that hose when cleaning the throttle body, I'll get a new clamp and test it again):
Vehicle Auto part Engine Car Fuel line

There is a connector connected to the same junction (pointed to by the question mark), what is it? Is it some temperature sensor? Here is a close up:
Auto part Engine Fuel line Vehicle Pipe


I also tried removing the intake pipe from the MAF and completely blocking any air from getting in from there with my hand. The engine ran better with no massive misfiring. This must mean a massive vacuum leak. Anyway most of the smoke came out of the pipe connection shown in the video above and I'd appreciate help identifying it and what to replace/how to fix it. I browsed ELSAWIN, but couldn't find information about this pipe, what is the name of it and its purpose.
 

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That oily connection that is more/less under the rear side of the intake manifold is where the PCV system begins (a metal housing attached to the block attempts to separate the last bit of oil from the vapor phase to minimize oil in the crankcase ventilation system). The PCV line (may be metal -vs-plastic?) should wrap around behind the cylinder head on its way to a point where it re-enters the intake tract after (downstream of) the MAF sensor. Looks like you also have a valve cover vent that has been "jury-rigged" with a non-OE hose. :screwy:

You should attempt to begin piecing together the plastic and/or rubber parts of the PCV system (use ETKA) so you can source all the degraded rubber/plastic parts you'll need before pulling the intake manifold. The metal? tube running behind the head and alongside the valve cover can be cleaned using your favorite solvent or hot soapy water.

Any plastic or rubber component in the PCV system has a life span of 12-14 yrs. That said, your engine will run much smoother after fixing the PCV "dirty" air leak (air leaking out of the PCV system has been metered by the MAF).
 

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Passat Variant B5.5 2001 manual 2.0L gas engine AZM 85kw
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Discussion Starter · #3 · (Edited)
I forgot to mention the car has 380k km on it.

I managed to locate the breather hoses here: https://volkswagen.7zap.com/en/usa/passat/pa/2001-226/1/133-133029/

The smoke leak was from the bottom end of the hose 29 (near 34). If I understand correctly then hose 29 is for the PCV and near 32 is the cylinder head ventilation. There don't seem to be other hoses for PCV and it also seems that I don't have EGR?

Below 34 there should be the PCV valve (is there only one?)? I guess I should change it also just in case.

To change the leaking pipe I thought about removing the intake manifold, but the bolt 36 is behind the alternator and I cannot access it (there is a similar bolt on the other side which can be accessed after removing the throttle body)... Would it be possible to remove the intake manifold by removing the clamps with the number 7? (I guess I can take out the alternator if needed). However if I remove the throttle body I should be able to replace that hose without taking out the intake manifold, so I'll try that first.

Edit: Searching ELSAWIN and ETKA more, I still am unable to find diagrams about the other end where the breather hose 29 goes to (I assume there must be a PCV valve there, also can't find any information about the PCV valve).
 

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Passat Variant B5.5 2001 manual 2.0L gas engine AZM 85kw
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Discussion Starter · #4 ·
I found the following thread:

Passat 2.0i AZM Engine Smoking At Idle.

One post there seems to suggest that the PCV valve is right in the intake hose, that the round connection with the electrical connector at hose 28 in the diagram (https://volkswagen.7zap.com/en/usa/passat/pa/2001-226/1/133-133029/) has the PCV valve, and I guess that the connector there is to control the PCV valve (the one which I asked about in the first post).

Anyway I removed the throttle body, then I removed the fuel injectors and the coil pack (first time removing them) and I managed to get the hose 29 out (which was the leaking hose shown in the video). The hose seems to have melted from the bottom part or maybe someone has tried to put some sealant on there which has melted, see the picture (higher res http://i.imgur.com/0t8dyXz.jpg). Or maybe it indicates some kind of a problem that the hose has melted?

Auto part Engine Vehicle Car Automotive engine part


So I'm ordering a new hose and a new o-ring, getting them next week and I hope it will fix the massive misfiring problem.
 

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Passat Variant B5.5 2001 manual 2.0L gas engine AZM 85kw
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Discussion Starter · #5 ·
I replaced the hose and fixed a couple more vacuum leaks. Now at least I can kill the engine by blocking the air intake with my hand.

The car doesn't run better, still has a lot of misfirings when under 2000 rpm.

If it is only misfiring at low rpms, I think the problem cannot be the coil pack? I'll replace the fuel filter, maybe that helps and if it doesn't I should get a fuel pressure gauge and measure fuel pressure, because then it is the only possibility left that can cause these problems?

One thing I noticed is that before starting the engine VAG-COM shows 0.35V on both O2 sensors, but when the engine is running it shows exactly 0.00V on both of them and the fuel trims both stay at 0%. Is this normal when misfiring or does it indicate some problem with the sensors?
 

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Passat Variant B5.5 2001 manual 2.0L gas engine AZM 85kw
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Discussion Starter · #6 ·
Here are a few more interesting things I noticed.

After I disconnected the MAF connector, VAG-COM still showed the air flow data in field 4 of group 002 and it changed when I stepped on the gas pedal. How can this be, if the MAF is disconnected?

The gas pedal always had some delay and you needed to push it down a little bit before it started reacting. Currently it behaves as follows (car is in neutral): without pressing the gas pedal VAG-COM group 062 field 3 (accelerator pedal position) shows 14.5%. I can press it to 18% without the rpm changing from around 800. Then at 18% if I keep it constant the engine cycles from 800 to around 2000 rpm and back continuously, if I press it more to 20% it goes to around 1000 rpm and I can then smoothly increase the rpms. Does this indicate some problem with the throttle body?
 

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Passat Variant B5.5 2001 manual 2.0L gas engine AZM 85kw
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Discussion Starter · #7 ·
In the end the misfires turned out to be caused by a bad MAF.

For anybody interested, the connector I kept asking about was for a heater that is in the PCV valve in the intake hose (to it seems like there is just some membrane there and not a valve), and the car does not have EGR (now I am thinking duh, just check if there is a connection from the exhaust to the intake, but before I had no idea what is the exhaust manifold for example).
 
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