Mystery vacuum line

[TomsPassat]

Have a 1996 Passat GLX VR6 (B4), auto tran. 2.8 L VR6 (AAA)

98k miles. Notable repairs since 1998: Instrument cluster, window regulator, strut mounts, intake boot, ignition switch (4 X).

Has been idling rough for years. Codes have appeared for misfires, but cylinder numbers vary ("random"). Had the wires replaced within the last year.

The misfires led me to suspect a bad coil pack. On the internet there are some interesting home remedies for this. However, the spray test has never revealed anything.

Still, on close inspection, the coil pack does show physical detioriation and a crack, about 1" , running from the corner where the bolt head cranks down running back toward the cylinder head. No visible current leakage when wet.

Moving on from there, began to suspect a vacuum leak, thanks to postings in this forum. This bit of advice has proved helpful. Then something strange came up while intently searching for vacuum leak.

Seems there is no EGR valve on this car. Searching through Bentley, gives some clear indication of where it should be, but there is no trace of an EGR or solenoid or two-stage switch. There are two electric leads in the area that have been grounded. And most amazing, there is a short length of vacuum hose coming off the brake servo vacuum line that is just lying on the heat shield above the exhaust manifold. Here was the vacuum "leak."

On the servo vacuum line coming off the intake manifold there is a back flow stop valve which has two nipples. One is covered by a green plug. The other is where this heat-shielded (braid covered) 10" vacuum line was connected, and leading to nowhere. The loose end of this hose was cracked as if it was connected to something at some time and then worn off from heat stress. Hunted around for several hours, taking off the plastic covers on the head, trying to find something to connect this vacuum hose to: Nothing seen.

Plugging this vacuum leak helped idle tremendously. (Though it's not yet perfect.) Finally!

According to Bentley, this hose would be the perfect candidate for an EGR vacuum connection. Length about right. But, as mentioned above, no EGR.

There is a large metal plug into the head assembly near the place where Bentley figure B-26-9 would place the EGR. The two grounded wires match color codes for EGR regulator and temp sensor.

This vehicle was assembled in Germany and may have originally been intended for Canada sale? The dealership sale actually was in the state of Maryland.

Questions:
1) Does the vacuum hose go to something that I missed?

2) Is there an EGR on this car that I missed?

3) If the answer to 2 is no, why is there no EGR valve on this car.

4) Why have all the so-called dealers (3) and VW "expert" shops (2) overlooked this "little" unconnected vacuum hose?

Thanks for any help anyone can provide.

[boschmann]

If the car was sold in the US it should have an EGR valve, an EGR vacuum control (regulator) valve and an EGR temp sensor (screwed into the base of the EGR valve unit). Someone probably removed it & plugged the holes. I'm suprised it's not setting codes for it. The vacuum regulator valve should be mounted on the back of the intake manifold & have red/blue & green/grey wires. There were two vacuum hoses that went to the valve, one from in front of the throttle plate & another off the plenum behind the throttle plate.

[TomsPassat]

Yes, B-mann, that's what had me stumped at first. I'm beginning to think this car was assembled for sale in CAN -God bless 'em - and crossed the border without emission certs.

But I've found the answer to the vacuum line connection in the last pages of Bentley under A/C. After going through the entire book, found the overly complicated system for controlling the fresh/recirculating air flap. Lots of hoses, connections, valves, and even an air bladder reservoir, all for this little flap it seems. Tomorrow it's to the store for a short piece of hose to reconnect this system to the main intake vacuum line.

But at least I can get going off the stop sign with a little more pep now.

Wish you were with me when I tried to convince the dealer there is a PCV valve on this car.

Thanks for the response. Keep up the good work.