Jug howl from Fuel filler - 986 Forum - The Community for Porsche Boxster & Cayman Owners

amagalla · 12-21-2020, 04:37 PM

Hello all,

I've posted this in several places but in the end, I think this might be the best place for this. As is in the title, I have the jug noise coming from the fuel filler vent. If I plug the vent, it stops. At one point I also got the 0446 code, but that has since gone away after changing one of the valves (more on this below). Here is what I've done so far to resolve this.

I've blown compressed air through every line I can find.
I changed out:

1. The Fuel Cap
2. The valve that is attached to the fuel filler neck.
3. The carbon canister
4. The evap valve under the intake manifold (I deleted the 0446 code after changing this and it hasn't returned.

But, after all this, I still have the jug noise, and the system won't go into ready state for a SMOG test.

There are 2 more valves under that right fender. They are the Purge Valve for Fuel Vapor Canister, and the Fuel Tank Vapor Control Valve. They are side by side in what seems to be the same plastic manifold. The purge valve is open with 0volts and closed with 12volts. When closed, it seems to hold both vacuum and pressure. The fuel tank valve is open with 12volts and closed with 0volts. When closed the valve can hold vacuum, but when I blow on it, it fairly easily allows air to pass. Is this normal for these valves? Is there anything else that I should be testing to resolve this issue? Please help. I'm at my wits end. I need to get this car SMOG'd and that can't happen till I solve this.

Thanks.
Tony

amagalla · 12-30-2020, 01:16 PM

Anyone have any ideas?

paulofto · 12-31-2020, 06:27 AM

I had the howl on my 03 S and partially covered the vent hole with duct tape, a very small piece covering half the hole. That was 4 years ago. I have not heard the noise since and have not had any issues filling the tank and no CELs.

amagalla · 01-01-2021, 11:32 PM

Thanks, but I'm looking to solve the problem, not hide it. I still have to pass SMOG.

Tony

maytag · 01-02-2021, 12:17 AM

You say after all you've done that it won't go into ready mode? What have you DONE to get it into ready mode?

I mean, have you performed the OBD drive cycle for the car at least 3 times?

If you have, and it still won't go into ready mode, but isn't popping codes, well then you've got a different problem.

If you've got a system failing, it will pop a code. No codes=no failing systems.

Sent from my SM-G970U using Tapatalk

amagalla · 01-03-2021, 12:40 PM

I've done the drive cycle many, many times. Still no luck. I did at one time get a 0446 code, but I changed the valve under the intake and cleared the code and haven't gotten it again. But, I still have the jug noise, and it still can't get to ready state for the smog test.

maytag · 01-03-2021, 03:58 PM

Quote:

Originally Posted by amagalla

I've done the drive cycle many, many times. Still no luck. I did at one time get a 0446 code, but I changed the valve under the intake and cleared the code and haven't gotten it again. But, I still have the jug noise, and it still can't get to ready state for the smog test.

As I say: if you're doing the drive cycle, it does the self tests and either passes or fails, going into ready mode or popping a code (not always a cel)

If neither are happening then you're either doing the drive cycle incompletely, or you have a problem with the computer.

What drive cycle steps are you taking? What does your drive cycle process look like?

Sent from my SM-G970U using Tapatalk

amagalla · 03-22-2021, 11:37 AM

It was the catalytic monitor that wouldn't go into ready mode, so I changed the fuel tank valve. During the time waiting for the part to come in, and me installing it, the battery went dead in the car, resetting the computer. After I changed the fuel tank valve, and recharged the battery, I took the car on the drive cycle. At this point the howling noise was gone, and the catalytic monitor went into ready mode. But, the secondary air system didn't (oh great, another issue). After doing some research, I found that, because of the computer reset, I had to put some miles on the car to gather enough data for the computer to understand the condition of the secondary air system. I finally got those miles on the car this weekend, and got the car SMOG'd. FINALLY! I'm so happy to have this issue behind me. The car is running great, and I think it's getting a bit better gas mileage too.

preppyr6 · 04-09-2021, 07:04 AM

Dealing with the howling noise since last fall. Replaced the fuel filler vent valve...no change. Replaced the purge valve housing and valves (2 cylindrical valves in black plastic housing)...no change. Kind of annoying having to go in and out repeatedly swapping parts to track this down. No consistent CEL codes, but def affecting idle smoothness.