Re: PCV Valve Retrofit - AES Motor (1997-2000)
I am driving across the U.S. in my 1995 Eurovan 5 MT. My mileage per gallon fluctuates: mostly over 20, but as high as 34 and as low as 17. I’d say the van gets peckish at altitude and isn’t keen on chilly weather.? If anyone could point me in the direction of what would incline this wonderful contraption to overachieve I’d be appreciative.?
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On Apr 17, 2023, at 1:47 PM, rmartin1962@... wrote:
?As many others have discovered, the PCV valve diaphragm for the AES motor fails most likely due to the harsh environment and/or age of the component. New replacements are essentially non-existent and crazy expensive if you find one. A used component, if you can find one, may fail in short order again given the age/construction of the component. In my case, the PCV valve failed in two ways. First, the vacuum line/side of the PCV was compromised allowing the suction of engine gases into the intake manifold causing a lean condition. The computer compensated by adding more fuel to correct the lean condition as measured by the front O2 sensor. Gas mileage had suffered for some time and I was unable to track down the cause as there was no check engine light nor was there a noticeable drivability issue. The partial load/long term fuel trim was running at 12.5% which is well above the specification of -5 to +5%. I replaced the original O2 sensors (140k miles) as their response were a bit sluggish and thought it may be contributing to the problem but there was no improvement in fuel trim. I then replaced most of the vacuum lines which were in fair shape but not terrible. In replacing the vacuum line to the PCV valve, I happened to check the PCV operation by sucking on the vac line to it and found the vac diaphragm had failed. I then plugged off the vac line and nipple to the valve. Bingo, fuel trims corrected and ended up in the range of 0-1% and the idle seems slightly smoother.? A further check of the PCV valve found that engine side diaphragm was also free flowing engine gases to the intake tube/throttle body in vacuum/load conditions which likely messes with the fuel trim in load conditions. Since replacement PCV valves are hard to come by, following is my fix that might be of interest to others. I wanted a dependable quality made part that was easily serviceable and/or replaceable along with no modifications to the original configuration should a quality OE style part become available (highly unlikely). I settled on Toyota part #12204-20040 which fits various 3.0-3.3L engines from 2001-2006. It's compact, designed to be mounted horizontally, and for an engine approximately the same size as the 2.8L VR6. Here's some pics of my MacGyver configuration. ? <02 PXL_20230417_165838965.jpg> <01 PXL_20230417_162647783.jpg> <03 PXL_20230417_163506712.jpg> <04 PXL_20230417_164318174.jpg> <05 PXL_20230417_164340366.jpg> <06 PXL_20230417_164404083.jpg> <07 PXL_20230417_164500355.jpg> <08 PXL_20230417_164624313.jpg> <09 PXL_20230417_164841546.jpg> <PXL_20230417_165710261.jpg>
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
More thoughts/questions about this problem.
Why is the fuel boiling in the gas tank? ?There are 3 reasons a liquid will boil: Head, Pressure, and Chemical composition.
Heat Too much heat is getting into the fuel. ?This is consistent with many reports that this happens when air temperature is hot, driving with air conditioning on, and driving uphill (which increases engine output and heat) and driving at a moderate speed. ?My theory is that when going slow enough, the airflow from the engine and radiator hits the gas tank exactly at the right angle (so the air hitting the tank is near 220F). ?However, if you are going faster, there is more ambient air to dilute the hot air from the engine, so the air hitting the tank is closer to 100F ambient.
Are there other sources of heat?
Mixture / Catalytic Converter: the cat is located near the right end of the gas tank. ?If the van is running rich, the cat will be extra hot, which could dump more heat into the tank. ? However, Don reported "I Insulated most of the exposed surfaces of the gas tank with adhesive backed foil heat reflecting material." which did not fix the problem.
Are there other sources of rich-running which do not trigger a CEL?
- bad Oxygen sensor (however, several reports that replacing Oxy sensors did not fix the problem)
- PCV valve - just today, a report of a failed PCV that did not trigger a CEL, but lead to a chronic rich-running condition: ? /g/eurovanupdate/message/163832
- leaky fuel injectors ???
Fuel Return: the fuel pump moves fuel to the injector manifold and then back to the tank. ?It seems like this round trip to the engine compartment and back would heat the fuel. ?Is there some failure mode where more fuel is flowing than normal, thus picking up much more heat? ? Is there some design change in the 2001 and later vans which reduces this problem?
Pressure A liquid's boiling temperature goes down with lower pressure. ?Most reports say it happens at altitude (personally, I've seen it at about 4000' up to 9000'). ?The fuel system is sealed and should hold pressure, and most reports say that opening the gas tank releases a lot of pressure, and almost nobody is having CELs showing small or large leaks. ? ?
However, perhaps there is some other part ?that is supposed to hold pressure but is failing at high enough pressure? ? For example, here's a video showing that an o-ring gasket in the gas tank filler tube neck can fail: ?
Chemical A liquid's boiling temperature depends on the liquid itself, and as previously mentioned, California gasoline formulations have changed over the years, and in particular Ethanol increases the vapor pressure. ?Summer gasoline blends are supposed to reduce the vapor pressure, but perhaps there are some gas stations still selling winter blends in the summer? ?I've not noticed any pattern with where I fill up with gas, other than that I usually fill up in Bishop CA heading to the sierras (but I've also had this problem heading to Joshua Tree). ? I feel like the problem is more likely to happen when the gas tank is closer to full vs. empty, but I'm not sure that makes sense.
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Re: PCV Valve Retrofit - AES Motor (1997-2000)
RMartin1962 - thank you for this great report.
How does one measure the "partial load/long term fuel trim" ? I have VCSD Lite (and am willing to upgrade to the paid version).
Mike
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The partial load/long term fuel trim was running at 12.5% which is well above the specification of -5 to +5%. I replaced the original O2 sensors (140k miles) as their response were a bit sluggish and thought it may be contributing to the problem but there was no improvement in fuel trim. I then replaced most of the vacuum lines which were in fair shape but not terrible. In replacing the vacuum line to the PCV valve, I happened to check the PCV operation by sucking on the vac line to it and found the vac diaphragm had failed. I then plugged off the vac line and nipple to the valve. Bingo, fuel trims corrected and ended up in the range of 0-1% and the idle seems slightly smoother.
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Re: PCV Valve Retrofit - AES Motor (1997-2000)
Nice work. Welcome to the world of the Cuban's!
As many others have discovered, the PCV valve diaphragm for the AES motor fails most likely due to the harsh environment and/or age of the component. New replacements are essentially non-existent and crazy expensive if you find one. A used component, if you can find one, may fail in short order again given the age/construction of the component.
In my case, the PCV valve failed in two ways. First, the vacuum line/side of the PCV was compromised allowing the suction of engine gases into the intake manifold causing a lean condition. The computer compensated by adding more fuel to correct the lean condition as measured by the front O2 sensor. Gas mileage had suffered for some time and I was unable to track down the cause as there was no check engine light nor was there a noticeable drivability issue. The partial load/long term fuel trim was running at 12.5% which is well above the specification of -5 to +5%. I replaced the original O2 sensors (140k miles) as their response were a bit sluggish and thought it may be contributing to the problem but there was no improvement in fuel trim. I then replaced most of the vacuum lines which were in fair shape but not terrible. In replacing the vacuum line to the PCV valve, I happened to check the PCV operation by sucking on the vac line to it and found the vac diaphragm had failed. I then plugged off the vac line and nipple to the valve. Bingo, fuel trims corrected and ended up in the range of 0-1% and the idle seems slightly smoother.?
A further check of the PCV valve found that engine side diaphragm was also free flowing engine gases to the intake tube/throttle body in vacuum/load conditions which likely messes with the fuel trim in load conditions. Since replacement PCV valves are hard to come by, following is my fix that might be of interest to others.
I wanted a dependable quality made part that was easily serviceable and/or replaceable along with no modifications to the original configuration should a quality OE style part become available (highly unlikely). I settled on Toyota part #12204-20040 which fits various 3.0-3.3L engines from 2001-2006. It's compact, designed to be mounted horizontally, and for an engine approximately the same size as the 2.8L VR6. Here's some pics of my MacGyver configuration.
?     
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PCV Valve Retrofit - AES Motor (1997-2000)
As many others have discovered, the PCV valve diaphragm for the AES motor fails most likely due to the harsh environment and/or age of the component. New replacements are essentially non-existent and crazy expensive if you find one. A used component, if you can find one, may fail in short order again given the age/construction of the component. In my case, the PCV valve failed in two ways. First, the vacuum line/side of the PCV was compromised allowing the suction of engine gases into the intake manifold causing a lean condition. The computer compensated by adding more fuel to correct the lean condition as measured by the front O2 sensor. Gas mileage had suffered for some time and I was unable to track down the cause as there was no check engine light nor was there a noticeable drivability issue. The partial load/long term fuel trim was running at 12.5% which is well above the specification of -5 to +5%. I replaced the original O2 sensors (140k miles) as their response were a bit sluggish and thought it may be contributing to the problem but there was no improvement in fuel trim. I then replaced most of the vacuum lines which were in fair shape but not terrible. In replacing the vacuum line to the PCV valve, I happened to check the PCV operation by sucking on the vac line to it and found the vac diaphragm had failed. I then plugged off the vac line and nipple to the valve. Bingo, fuel trims corrected and ended up in the range of 0-1% and the idle seems slightly smoother.? A further check of the PCV valve found that engine side diaphragm was also free flowing engine gases to the intake tube/throttle body in vacuum/load conditions which likely messes with the fuel trim in load conditions. Since replacement PCV valves are hard to come by, following is my fix that might be of interest to others. I wanted a dependable quality made part that was easily serviceable and/or replaceable along with no modifications to the original configuration should a quality OE style part become available (highly unlikely). I settled on Toyota part #12204-20040 which fits various 3.0-3.3L engines from 2001-2006. It's compact, designed to be mounted horizontally, and for an engine approximately the same size as the 2.8L VR6. Here's some pics of my MacGyver configuration. ?          
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Re: used Charcoal canisters available on SAMBA
Do your home work and caveat empor. There’s a decades long trail of misery in the VW parts desert of Nevada…. On Tue, Apr 11, 2023 at 1:14 PM Jonathan Mackenzie via <jonathanmackenzie= yahoo.com@groups.io> wrote:
Very useful, thanks!? I see they have a website and claim to specialize in NLA parts.??
Has anyone used them?
- Jonathan
On Tuesday, April 11, 2023 at 12:53:05 PM PDT, Spencer Allen < soxndubs1951@...> wrote:
Came across this ad on the SAMBA Eurovan parts site. Don't know anymore than what it says.
--
Justin
2000 EVW 1.9TDI Syncro 5-spd
492k mi :-)
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Re: used Charcoal canisters available on SAMBA
Very useful, thanks!? I see they have a website and claim to specialize in NLA parts.??
Has anyone used them?
- Jonathan
On Tuesday, April 11, 2023 at 12:53:05 PM PDT, Spencer Allen <soxndubs1951@...> wrote:
Came across this ad on the SAMBA Eurovan parts site. Don't know anymore than what it says.
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used Charcoal canisters available on SAMBA
Came across this ad on the SAMBA Eurovan parts site. Don't know anymore than what it says.
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
Macon, Don, and others, thank you all so much for joining the discussion!
It's nice to know I'm not alone, and maybe with more minds and more data, we can figure this out?
Mike
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On Apr 6, 2023, at 2:32 PM, Don Daynes <ddaynes@...> wrote:
Hi, long time lurker. Don't think I have ever posted.
2000 EVC with the EXACT same issue/ symptoms as?Michael Diehr has related. Problem really only happens on one road traveling to somewhere I like to camp. Things I have done: Used this forum and online references to test the evap canister and system. Could not find anything wrong. Would have replaced it if it was still?available. Replaced gas cap. Wrapped the exhaust piping with fiberglass heat tape before and after the cat near the gas tank. Insulated most of the exposed surfaces of the gas tank with adhesive backed foil heat reflecting material. Replaced the radiator. Removed the engine oil based transmission cooler and replaced it with a tranny cooler in front of the radiator.? AND added a second, thermostatically controlled tranny cooler with a fan, located aft of the gas tank. Nothing I have done has had any effect except for somewhat lower engine and trans temps, as monitored with a Scan gauge. Still gets hot, has exterior gas smell, excessive gas tank pressure, and boiling/gurgling noises from the gas tank when going up that road.? I have learned to monitor temps when going up that road and stopping at a couple of convenient?places on the way up. I carefully?vent the gas tank, and wait for the engine and tranny cooler fan to stop running before proceeding. May contemplate?replacing the gas tank per the post that had luck with that. The change in gasoline properties?seems as likely as anything. Giving up trying to do anything more to mine for the time being. Just waiting for the definitive?fix posted here.
Don Daynes? Anaheim, CA ?
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
Hi, long time lurker. Don't think I have ever posted.
2000 EVC with the EXACT same issue/ symptoms as?Michael Diehr has related. Problem really only happens on one road traveling to somewhere I like to camp. Things I have done: Used this forum and online references to test the evap canister and system. Could not find anything wrong. Would have replaced it if it was still?available. Replaced gas cap. Wrapped the exhaust piping with fiberglass heat tape before and after the cat near the gas tank. Insulated most of the exposed surfaces of the gas tank with adhesive backed foil heat reflecting material. Replaced the radiator. Removed the engine oil based transmission cooler and replaced it with a tranny cooler in front of the radiator.? AND added a second, thermostatically controlled tranny cooler with a fan, located aft of the gas tank. Nothing I have done has had any effect except for somewhat lower engine and trans temps, as monitored with a Scan gauge. Still gets hot, has exterior gas smell, excessive gas tank pressure, and boiling/gurgling noises from the gas tank when going up that road.? I have learned to monitor temps when going up that road and stopping at a couple of convenient?places on the way up. I carefully?vent the gas tank, and wait for the engine and tranny cooler fan to stop running before proceeding. May contemplate?replacing the gas tank per the post that had luck with that. The change in gasoline properties?seems as likely as anything. Giving up trying to do anything more to mine for the time being. Just waiting for the definitive?fix posted here.
Don Daynes? Anaheim, CA ?
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
Dear friends:
Michael Diehr described the symptoms thus:
Some of us experience the following symptoms:
- when it's very hot out (like 95F or higher)
- driving at a medium speed (20-40 mph)
- arriving at a high altitude (5000' - 7000' )?
- strong raw gas smell (around the gas tank area, not from the engine compartment or tailpipe)
- gas tank literally sounds/feels like it's boiling
- pressure in gas tank (relieved if you open the gas cap)
- typically no CEL or codes via VCDS
- van otherwise drives just fine
- once the van cools down, starting and driving at altitude is normal
- reports are more common with the 1997-2000 Eurovans vs. the 2001-2003 Eurovans (which have a redesigned Evap system)
- this problem seems new - several of us who drive the same routes each year began to notice it 5-10 years ago.
- some people report that it gets better with parts replacement (typically N80)
- however, many of us have R&R many parts (Evap canister, N80 valve, gas cap, Oxygen sensors...) with no improvement.
I will just tell you that I had this identical constellation of problems in my 1997 EVC that started in July 2014 when my van had 139,000 miles.?
I replaced the fuel tank cap and associated seals and hose clamps. I replaced a bad check valve and the gas tank with a new one in July 2014; then replaced the gas tank again under warranty (for the 2014 tank) in July 2015 and I replaced the carbon cannister at the same time. The EVC then had 147,000 miles. I also removed the belly pan to give better ventilation to the engine so that the heat is not all directed around the gas tank.
The problem described did continue, despite all this. I am told by my current mechanic that this problem was fixed in the 2000-2003 EVCs, as the vapor recovery system was changed substantially and there is no longer a tail on the carbon canister that exhausts fumes directly onto or into the frame when the canister cannot absorb all the vapor.
Gas fumes can be caused by a variety of things. Some of those things, are fixable. I am going to paste below a string of comments from the VW list in 2014-2021 on the topic, and you will see the comments, a fix or two for certain causes, and the frustration that this has caused:
Wolfgang Baudler, EV list, August 29. I had the same problem as the original poster with fuel fume smells inside and outside on my 1995 EV. Smell was intermittent, seemed to depend on temperature, weather etc and also was more pronounced when going uphill. ? In my case it turned out to be a broken breather tube, the line connecting the top of the fuel tank with the EVAP canister.? ? It was broken at an inaccessible location near the top of the tank. Took a long time to track this down, but once I have replaced that breather tube the fume smells went away. The whole line was very brittle, so possible that this might be the cause for others as well. ? I managed to replace it without dropping the tank, but you will need to cut the carpet in the cabin for access to the top of the tank. It would be much easier to inspect and replace with the tank dropped. ? Part number for the 95 is 7D0-201-059-C? ? Wolfgang ? From: "websailn2@...?[ev_update]" <ev_update@...> To:?ev_update@... Sent: Wednesday, August 20, 2014 1:51 PM Subject: [ev_update] Re: Fuel Evap System for 1997 Eurovan ? ? There are a few diagrams of the system in the Bently Manuals, but not much of a description of operation. Without doing some more study here is a general summary off the top of my head of how things work: In your fuel tank, you have liquid on the bottom and vapor on top of that. As you refill the tank, adding more liquid, the vapor needs somewhere to go. In the old days, it just vented into the environment around the side of the fill nozzle. Now, for environmental reasons, it's forced into a charcoal canister, where the vapor is adsorbed. Later, when the engine is running and up to operating temperature, the canister is connected to the intake manifold by a valve that allows the vapor to be drawn off and burned, cleansing the canister for the next refueling cycle. There are a number of check valves in the filler neck assembly that allow this to happen as described and you can stare at the Bentley diagram for a long time trying to figure it out. ? One issue regularly reported, is overfilling the tank thereby pushing liquid into the canister. The liquid turns the charcoal granules into a solid briquette which will block the canister, sending the vapor out around the nozzle like the old days. You'd smell it, but also likely experience the gas pump nozzle clicking off a lot. Doesn't sound like you have that problem. ? Alternately, the canister may have lost some of it's "storage" capacity. It may be "full" because the stored vapor is not being drawn off because of a blockage in the system or a failure of the vapor recovery valve. You'd smell this too - the canister is behind the driver side wheel and has a breather tube that would expel any excess vapor that couldn't be adsorbed. However, I recollect there is a self test of the system on start up so you'd get a check engine light if this is the problem - I think. ? Finally, over time, the charcoal granules get pulverized so there is more void volume in the canister, less adsorption surface - again less vapor storage capacity. So any vapor that couldn't be adsorbed would also pass out the canister's breather and you'd smell that. ? One more obscure thing: some people have mounted things under the front seat - stereo amps and such, inadvertently drilling through the top of the tank. That would give you a gas smell but most of the time though, not just during refueling. ? I have heard of the trick of leaving the gas cap off to "dry out" the canister but I don't think this actually works. One, I don't believe the system check valves are oriented to allow this and two, a damage canister (solid brick or excess void) can't be restored with just an airing out. ? If you problem is persistent, a new canister is probably the easiest solution. If it isn't affecting drivability, it's just an environmental issue. ? OK, lost my head on this post. I need a life. ? Regards, Duane? 2000 EVC ? Thread on the issue on Eurovan FB page Feb. 18, 2021Hello, I own a T4 shop and we see this often. We see dirt/debris/insect nest clog the breather lines, cracks in the tank and/or hoses. A saturated canister / stuck purge/evap check valve can also cause this. ? Tom Smith My 2002 is doing the same thing currently.?? ? Terry Schmerk My 99 had the same problem..replaced the gas tank..problem solved ? Chelo Cobian Terry Schmerk cost? Like ?· Reply · 14h Terry Schmerk Chelo Cobian the tank was only 75...out of a used one from a scrap yard...this was in Toronto..shipping for it was about the same amount ? Chelo Cobian My 2000 has that same smell...sometimes. had shop check it out and they found no cracks or leaks and everything working fine?? ? Obaid Zamani Snow and ice / Debris dirt there’s breather lines by your rear wheel for your gas tank I had this issue years ago over the winter in northern Virginia ? Gary Lewis I had a the same issue. My issue was pressure buildup in the tank when I removed the cap just as you stated. I could smell gas at times before removing the cap. It turns out that there is a small valve that gets pushed in when the gas cap is inserted. The gas vapors are then released into the charcoal canister etc. All i had to do is carefully bend the flat metal v shaped valve out a bit so when the gas cap was inserted the valve would open into the line and release the tank pressure. It's on the left inside. Hope that makes sense. ? Chelo Cobian Gary Lewis anyway you can take a pic and point to it? ? Mark O'Neil Conner '95 EVC, here. Been to this movie. My mechanic replaced the fuel line, it was badly corroded. Problem solved. ? Corporal Ninny I have a ‘97 with 190K had a similar issue and replaced my gas cap which solved the problem - I bought this cap off ebay but don’t see it listed anymore it was just under $15 May be an image of text that says 'Item info Seat VW I $14 Shipping ad'
Macon Cowles
Boulder
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
On Apr 4, 2023, at 2:13 PM, Duane <txpigeon@...> wrote:
Pressure increases the boiling temperature for all liquids But... Increased pressure also causes increased temperature.
I've never run across anyone with a properly working EVAP system that had "boiling" or excess pressure. Well, there may be at least two of us on this very email list saying it's happening to us. :-) Mine acted up once, but it turned out to be the N80 clogged, so pressure built in the system.
Since the N80 cycles constantly after the engine warms up, there should be no way for it to build pressure. Was this in your 2005 Rialta? What were the conditions (air temperature, altitude...) I think it's possible that we are seeing different scenarios: (A) a clogged or broken N80 will cause these symptoms under relatively benign conditions (low altitude, warm but not hot) (B) in the 1997-2000s, a perfectly working evap system can get overwhelmed under rare conditions. Mike p.s. thanks for engaging on this, I appreciate the back & forth ideas...
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
On Tue, Apr 4, 2023 at 03:21 PM, Michael Diehr wrote:
Pressure increases the boiling temperature for all liquids
But...? Increased pressure also causes increased temperature.? I've never run across anyone with a properly working EVAP system that had "boiling" or excess pressure.? Mine acted up once, but it turned out to be the N80 clogged, so pressure built in the system.? Since the N80 cycles constantly after the engine warms up, there should be no way for it to build pressure. -- Duane 05HD Rialta 220K Miles
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
On Apr 4, 2023, at 11:24 AM, Duane <txpigeon@...> wrote:
On Tue, Apr 4, 2023 at 11:31 AM, Michael Diehr wrote:
If the fundamental problem is gasoline boiling in the gas tank?I believe this is because the vapor can't escape, building up pressure.? That all goes back to the EVAP system not operating properly.?
--?
Duane
05HD Rialta
220K Miles The idea that the EVAP system is malfunctioning is very logical and I'm not ruling it out, but I am leaning towards other explanations.
Pressure release / vent failure? Pressure increases the boiling temperature for all liquids - so if the gasoline in the tank is boiling, it's actually not under enough pressure. (Or, it's just way too hot)?
The EVAP system has a LDP (leak detection pump), and although it's vacuum operated, it tests for leaks by holding a positive pressure. ? In my van there are no LDP codes in normal operation, but I've accidentally triggered the "small leak" and "large leak" codes when I was messing around, which leads me to believe the LDP is working, and my system is tight.
I believe in the Eurovan the LDP is dual purpose, and is also the vent. ?From the same guide:?
The LDP is integrated into the EVAP system and can have two functions. The LDP can: ? pressurize the EVAP system and detect a drop in pressure that would indicate a leak ? function as the EVAP Canister Vent on vehicles that do not have a separate EVAP Canister Vent.
I'm not clear what happens if the system gets over pressured - does the LDP vent have some sort of safety blowoff valve? ?Could that blowoff valve have failed somehow? ?
Capacity Logically, the evap system does not have infinite capacity to deal with vapor.
For example, the evap guide you referenced says:
A 1% concentration of fuel vapor from the EVAP Canister can vary the air/fuel mixture by as much as 20%. This can have a drastic effect on engine driveability and vehicle emissions.
I think it's quite possible that this system has a limit, and there is some combination of heat, altitude, and gasoline volatility which could overwhelm the system, so the purge can't keep up, and eventually the pressure is released, even if the system is 100% functional as designed. ??
Under this theory, VW designed the 1997-2000 evap system to handle "normal" conditions, but gasoline changes in the last decade were not something they planned for.
As I say, I'm not sure of any of this, just trying to get more data and see what theories fit the evidence...
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Re: Eurovan Gasoline Fumes when Hot & High - Recap
On Tue, Apr 4, 2023 at 11:31 AM, Michael Diehr wrote:
If the fundamental problem is gasoline boiling in the gas tank
I believe this is because the vapor can't escape, building up pressure.? That all goes back to the EVAP system not operating properly. -- Duane 05HD Rialta 220K Miles
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Eurovan Gasoline Fumes when Hot & High - Recap
To recap:
Some of us experience the following symptoms: - when it's very hot out (like 95F or higher) - driving at a medium speed (20-40 mph) - up a steep hill - arriving at a high altitude (5000' - 7000' )?
Positive symptoms: - strong raw gas smell (around the gas tank area, not from the engine compartment or tailpipe) - gas tank literally sounds/feels like it's boiling - pressure in gas tank (relieved if you open the gas cap)
Negative symptoms: - typically no CEL or codes via VCDS - van otherwise drives just fine - once the van cools down, starting and driving at altitude is normal
Background: - reports are more common with the 1997-2000 Eurovans vs. the 2001-2003 Eurovans (which have a redesigned Evap system) - this problem seems new - several of us who drive the same routes each year began to notice it 5-10 years ago. - some people report that it gets better with parts replacement (typically N80) - however, many of us have R&R many parts (Evap canister, N80 valve, gas cap, Oxygen sensors...) with no improvement.
Design flaw? The Eurovan's gas tank is right behind the engine, and with the right combination of factors (speed, temperature, altitude) you can get in a situation where tons of hot air are coming off the engine and radiator, blowing right by the gas tank, causing the gasoline to boil. ?Even if the N80 and evap system are working properly, gas fumes are created faster than the engine can burn them, eventually overloading the evap system leading to pressure release of gasoline fumes. ? ?An argument consistent with this is that the 2001 and later models have a beefier evap system, seem to be less likely to have this problem, suggesting that VW may have indeed fixed this flaw.
The main argument against this theory is that many of us feel like this is a new?problem that didn't happen when the van was younger, suggesting that something changed.
Malfunction? If something has changed, it's most logical to think something has worn out or broken in our vans. ?E.g., if the evap system were working better, the problem would go away. ??
The main argument against this theory is that several of us have R&R multiple parts and never found a cure.
Could it be the Gasoline? Perhaps something else has changed? ? If the fundamental problem is gasoline boiling in the gas tank, perhaps gasoline formulations have changed to increase the vapor pressure??
In fact, around 2003 California phased out MBTE and started using about 5% Ethanol, and around 2010 rules changed to allow up to 10% ethanol in California fuel blends. ??
It so happens that E10 gasoline is allowed to have a Reid Vapor Pressure (RVP) up to 1 psi higher:?
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Re: Oxygen sensor, N80, gassy start and when hot & high?
Unbelievably, parts.vw.com still shows VW 7D0201801? as 'Available For Order'.? Has anyone successfully ordered anything from this outfit?? I have ordered from internet sellers before who seemed to have something in stock (not VW related) - they immediately put the credit card transaction through and then announced they were waiting on stock and became difficult to deal with. I had to contact the credit card company to cancel the transaction and get a refund. A good internet seller will not run the card number until the goods are dispatched.
- Jonathan
On Tuesday, April 4, 2023 at 08:10:35 AM PDT, Michael Diehr <md03@...> wrote:
Further updates:
1. The part (VW 7D0201801) was showing as "AVAILABLE FOR ORDER" on parts.vw.com so I placed an order.? They charged my credit card and emailed to say the order was being processed.?
A few days later, I received another email saying
"The evap canister is no longer available. It was discontinued 1-04-2016."
2. David, who has almost identical symptoms in his 2000 EVC, such as boiling in the gas tank, fumes, pressure when releasing the gas cap, when at altitude and hot temperature, replied, saying
"I was not able to find a solution, but I only experience the issue when climbing a long steep hill at altitude.? Since I generally only encounter this once a year (on my way to Pinecrest CA) I just deal with it.? I tried replacing the N80 and both Oxygen sensors and then really just decided that I was chasing my tail and spending unnecessary money."
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Re: Oxygen sensor, N80, gassy start and when hot & high?
Further updates:
1. The part (VW 7D0201801) was showing as "AVAILABLE FOR ORDER" on parts.vw.com so I placed an order. They charged my credit card and emailed to say the order was being processed.
A few days later, I received another email saying
"The evap canister is no longer available. It was discontinued 1-04-2016."
2. David, who has almost identical symptoms in his 2000 EVC, such as boiling in the gas tank, fumes, pressure when releasing the gas cap, when at altitude and hot temperature, replied, saying
"I was not able to find a solution, but I only experience the issue when climbing a long steep hill at altitude. Since I generally only encounter this once a year (on my way to Pinecrest CA) I just deal with it. I tried replacing the N80 and both Oxygen sensors and then really just decided that I was chasing my tail and spending unnecessary money."
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Re: Oxygen sensor, N80, gassy start and when hot & high?
In trying to solve the mystery gassy smell on my 2000 Eurovan, I came across a similar story in the archives from "Dave dave2napa@... <mailto:dave2napa@...>" which sounds almost identical to the problems with my 2000 EVC.
Is dave2napa still on the list?
Dave, if you are here, did you find the solution?
Here's what Dave wrote back in 2015:
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On Feb 20, 2015, at 7:28 AM, dave2napa@... [ev_update] <ev_update@...> wrote:
Hi All,
While driving to Yosemite this past weekend, I experienced a strong gas odor in the interior of our 2000 EVC. We were traveling uphill at low speeds (35 mph) at around 5,000 feet of elevation. The car was driving just fine except for the gas smell. The smell started just as we approached the entrance gate to the park, the ranger and I both noticed that the car also has a strange mechanical humming noise. I pulled over and could not locate a leak and when I started the car back up, the mechanical noise was gone. Here is the strange part, with the engine off, I placed my hand on the gas tank and it felt warm and the contents appeared to be moving around (boiling/bubbling?). The engine and tranny temperatures were normal (190 and 212). We decided to continue on with the windows rolled down and after we started to descend, the smell went away, but shortly thereafter, the check engine light c ame on and the gear selector indicator light went out. All the while the car drove normally, but we headed straight to the garage in Yosemite Valley (fun way to start the trip).
The garage in Yosemite valley pulled the following codes: P0740 (torque converter clutch circuit malfunction TDC) and P0134 (Oxygen Sensor 02 Circuit no activity detected). However they could find nothing wrong and the car ran perfectly the rest of the trip.
Back in Napa, my local shop discovered that we have a vacuum leak at the brake booster hose. They will replace that tomorrow and see if that helps.
Any thoughts?
Dave
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Re: Oxygen sensor, N80, gassy start and when hot & high?
Thanks, Duane, I'd love to see a copy of the 841903 document if possible. ?Can you just attach as email?
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On Feb 20, 2023, at 6:58 AM, Duane <txpigeon@...> wrote:
On Sun, Feb 19, 2023 at 06:00 PM, Michael Diehr wrote:
I've read some posts mentioning that failing Oxygen sensors can cause the N80 to malfunction and not throw a CEL, but I'm wondering if this is rumor or there's actual science behind it?
I don't understand all I know about this, but I believe that could be true under exceptional circumstances.? The ECM controls the N80 based on other inputs, including the O2 Sensors.? However, in most situations where the O2 sensors were 'bad', you'd get a CEL.? I think they'd have to be reacting very slowly to not throw a CEL nor open the N80.? The training manual for EVAP, 841903, says: "Based on information from the Oxygen Sensors about the fuel to air ratio in the exhaust, the ECM opens the EVAP Canister Purge Regulator Valve and allows vapor from the EVAP Canister to be drawn into the Intake Manifold." BTW, I was going to upload the relevant section, but apparently the group is set up so that only moderators can upload files or photos.? They could be included as attachments though. -- Duane 05HD Rialta 220K Miles
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Justin Soares
Spencer Allen
Duane