On Feb 7, 2023, at 5:32 PM, Michael Diehr <md03@...> wrote:

?My 2000 EVC has over 100k miles.

In the past few years I've noticed some symptoms, and I wonder if they could be connected:

* very gassy / rich smelling exhaust at startup - not "evacuate the neighborhood" bad but "air out the garage for a while" bad. Definitely coming from the exhaust pipe only.
* after the van warms up, this stops, and subsequent warm starts don't have this problem
* sometimes, a "tick tick tick" noise upon cold start, especially if the van hasn't been driven in weeks. This usually goes away in minutes as the van warms up, and often doesn't come back for days.
* when it's very hot and/or at high altitude, gas fumes - these are not coming from the exhaust, but possibly from the EVAP system hoses around the gas tank or maybe from engine compartment?
* sometimes the tank "gurgles" after filling, and this happens even after I rehabilitated and later replaced my EVAP canister

On the positive side:
* R&R evap canister
* new gas cap
* new N80 valve
* all new plugs, wires, and coil packs (which fixed some misfires, but did not change these other symptoms)
* no codes
* MPG is expected
* passes smog

Basically, if you only encountered this van after it had warmed up, and never took it to the high desert, you would think it was running perfectly.

I have a few ideas - some of these are my own, and some distilled from prior posts on the list:

1. this is all normal, the van always runs in "open circuit" mode at startup, which runs rich, and I'm not remembering how gassy older vehicles are (I do live in California and my other car is an EV).
And, the other gassy smell when hot & high is due to extreme driving conditions (110F, high altitude) and just a flaw with Eurovans.

2. the "tick tick" noise sounds like a hydraulic valve lifter that lost pressure, which could cause incomplete combustion leading to the gassy exhaust.
Once the lifter pumps up, the problem goes away. (This does not explain the hot + high gassy smell, however)

3. it's one of the oxygen sensors? An oxygen sensor malfunction might not trigger a CEL?
But a malfunction could lead to rich running problems, explaining the super rich running at cold start.
Also, (so I've read) oxygen sensors are tied into the N80 (the valve which pulls gas fumes from the tank / charcoal canister and burns them).
If one or both of the Oxygen sensors is bad, this could explain both problems (ultra rich @ startup, and N80 not venting enough).

4. bad fuel injector - it gets stuck open when cold, dumping fuel into the cylinder, but when very hot, leaks into the engine compartment?
(This seems unlikely to me...)

I like #3 because it explains both problems, but am not sold on any theory at the moment, and some of my assumptions are likely wrong.

On Feb 17, 2023, at 6:45 PM, Duane <txpigeon@...> wrote:

On Fri, Feb 17, 2023 at 08:29 PM, FlashVan wrote:
when I opened the gas cap it began to “boil” and gas actually spewed out of the filler tube That's a common sign that the N-80 valve (or related tubing) isn't working. The whole purpose of the valve is to allow the fumes to be sucked into the engine to be burned after the engine warms up.
--
Duane
05HD Rialta
220K Miles

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

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