Purge Valve Noise - 2000 VR6

[Snort]

My N80 purge valve seems to make a lot of noise. No check engine light, no codes. Most noticeable when idling it runs for a while making rapid oscillating noises, stops and stops seemingly randomly. I had an aftermarket valve on it and switched to a used VW branded one which seemed to quiet it down a bit but still at times very loud when it's running.

Does this seem normal, or is it perhaps working overtime due to some other piece of the evap system being out of whack such as the charcoal canister or leak detection pump and whatever valves it might have?

[xEVC]

I think this is normal behavior. Here's a graph I made using VCDS of several parameters, including the N80 duty cycle - the light blue line labeled "evap %" in the graph. You'll notice it's all over the place while driving, and even when idling (the right 1/3 of the graph) it will sometimes slowly climb up, which would correspond to the ticking noises getting faster and faster.

I wouldn't call it "loud" - when I'm sitting in the van, with the windows closed and the hood closed, I can sometimes hear the tick tick noise when idling if I pay attention.
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[Snort]

Mine is more than a tick tick. I can drown it out with normal stereo volumes but with the radio off and the engine at idle it is often a noise that can not be ignored.

[logans5vw]

I don't recall ever hearing the N80 valve on my 02 mv while engine was running. But recently the N80 valve started making a loud clicking noise and caused engine to run rough. Replaced it with a new one and all's well.

[xEVC]

Testing the N80 is easy:
- with the engine off
- un-plug the electrical connector
- un-plug the hose line from the N80 at the intake manifold
- put the hose in your mouth, and suck - you should not be able to get any airflow
- apply 12VDC across the electrical connectors on the N80 - you should hear a soft click, and be able to suck some air (with fuel vapor).

Beware - when I replaced my N80 a few years ago, I purchased one from a FLAPS, and it was defective out of the box.

Bought another one (BOSCH) from a VW-specific vendor ( https://europarts-sd.com/evapcanisterpurgevalve1997-2000.asp ) which worked fine.
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[HeyCrutch]

FCP Euro also sells the Bosch N80 Valve for our Eurovans. And they offer a pretty good Lifetime Return policy.
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-2003 EV MV Wk - Forest - 51k
-2002 EV Camper - Ghost - 82k
-2003 EV GLS - Fluffhead - 176k

-1997 EVC - 12vVR6 (SOLD 5/2025)

[Snort]

I'm wondering if there is too much vacuum in my system causing the purge valve to work overtime. Is there a vent on the leak detection pump that is supposed to open when the purge valve is running? I would think that there should be some kind of valve to let fresh air into the canister when the purge valve is running.

[xEVC]

The N80 purge valve has one goal: pull gasoline fumes from the charcoal canister so they can be burned in the engine. This makes room for the canister to store more fumes later.

Why is there an N80 valve at all? The reason the N80 doesn't run fully open is that the fumes affect the air/fuel mixture, which could cause the engine to run overly rich.

Also, when you are decelerating with the throttle closed, the computer cuts off gasoline delivery to the fuel injectors entirely. If the N80 were open at that point, you'd just be letting raw gasoline flow into the cylinders, then out the exhaust ports.

Since the entire goal of the Evap system is to prevent gasoline emissions, that wouldn't work.

So, the computer tries to strike a balance. It opens the N80 valve partially, then measures the effect by using the Oxygen sensors to detect the change in fuel/air mixture. It adjusts it up (or down) by varying the duty cycle (from 0% to 100%). The rapid opening and closing is the "click click" sound you hear.

In my opinion, there is nothing unusual about your N80 running at various speeds at various times.

However, what is unusual is your description that it's "loud".

The N80 is mounted inside a rubber case, and the rubber case is mounted to the engine. I presume this is to make it quieter.

I wonder if your N80 is not mounted properly, so the N80 case is directly touching some part of the engine, increasing the noise?

Can you post a picture of your N80?
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[Snort]

[xEVC]

That looks quite similar to mine, though I notice a couple of differences:


1. On the right side in your picture, there's a hose clamp which doesn't look stock.

2. In both our pictures, there is a white vacuum hose that connects to a black rubber hose. But it seems to be going different directions in the two pictures.

Could one of us have a misrouted vacuum line?

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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[Snort]

I'm not sure why that clamp is there, its on the low pressure/vacuum side of the N80 valve and the hoses are all good, so it's somewhat redundant.

My vacuum line goes to the same place as yours, up between the heater core hoses, it just takes a curve to the left before it reaches that point. It's fastened to other hoses in two places with factory clips then tees into a line coming off the brake booster hose.

[Abscate]