IROCZ1989

iTrader: (1)

What are all doing with the canister. Have a dominator ECU. Guess I could set up and output to work the solenoid. Confused here . Any help appreciated thanks.

Abubaca

iTrader: (3)

Well the Holley isn't legal for OBD, assuming your state requires it, so you're already outta luck for legality reasons. ....but for fumes and smell/venting, etc, etc. I'm running the Holley HP and I got rid of the charcoal canister all together. Found a lot of the Factory Five guys (and certainly many others) running a home made filters.
-Mine is made of PVC tube and is about the size of a monster energy can.
-Bought caps for both ends.
-Drilled some holes in one end.
-Plumb a brass, barbed pipe fitting on the other.
-Rubber line between the hard fuel line and your filter.
-Fill with fish tank filter charcoal
-replace charcoal every six months or so.
Works great!

Abubaca

iTrader: (3)

I looked into setting up an output, but considering it's already "technically" illegal anyway....and there's almost no way (if at all) to program all the conditions as to when the factory ECM purges the tank, into the Holley system....I felt it was a losing effort.

IROCZ1989

iTrader: (1)

15 years an older is emissions exempt in my state. Is the factory ECU purge on a timer? Or is it parameters? I wanted to keep it if I could.

Abubaca

iTrader: (3)

I'm sure you could set up an output, but what would be your trigger? What condition would you use?

Since gasoline vapors contain HC, these vapors must not be allowed to escape from the fuel tank to the atmosphere. In the EVAP system, a hose is connected from the top of the fuel tank through the tank pressure control valve (TPCV) to a charcoal canister. Gasoline vapors from the fuel tank are stored in the charcoal and then purged into the intake manifold when the engine is running under certain conditions. A fresh air line is connected to the charcoal canister. Some EVAP systems have a fresh air intake directly on the bottom of the canister with a filter in the air intake. EVAP systems vary depending on the vehicle make and model year. Always obtain the exact system details from the vehicle manufacturer's service manual. A canister purge solenoid is connected in the purge hose from the canister to the intake port near the edge of the throttle. The PCM provides a ground for the canister purge solenoid winding to operate the solenoid. How the system works The PCM energizes the canister purge solenoid and allows vacuum to purge vapors from the canister under these conditions:

1. 150 seconds have elapsed since the PCM entered closed loop.
2. Coolant temperature is above 176 degrees F. (80 degrees C.).
3. When the PCM is not enabling injector shut-off, such as on vehicles with traction control while one drive wheel is spinning.
4. The idle contact switch in the IAC motor is open.
5. Vehicle speed is above 20 mph.
6. Engine speed is above 1,100 rpm.
7. The engine metal temperature sensor is not indicating excessive temperature.
8. Low coolant level is not indicated.

If any of these conditions are not present, the PCM does not energize the canister purge solenoid, and the gasoline vapors from the fuel tank are stored in the canister. When the engine is running, intake manifold vacuum is supplied to the TPCV valve. This vacuum opens the valve and allows vapors to flow through the valve into the canister. When the engine is not running, the TPCV valve closes, and fuel vapors are contained in the fuel tank. If the tank pressure exceeds 15 inches of water with the engine not running, this pressure forces the TPCV valve open and allows vapor flow to the canister. The canister contains a liquid fuel trap that collects any liquid fuel entering the canister. Condensed fuel vapor forms liquid fuel. This liquid is returned from the canister to the tank when a vacuum is present in the tank. This liquid fuel trap prevents liquid fuel from contaminating the charcoal in the canister. The EVAP system reduces the escape of HC evaporative emissions from the gasoline tank to the atmosphere. Mechanically Operated EVAP System In some EVAP systems, the purge hose between the charcoal canister and the intake manifold is opened and closed by a thermal vacuum valve (TVV) that is mounted in the cooling system. The TVV contains a thermowax element and a plunger. When the thermowax is heated, it expands and moves the plunger. If the engine coolant temperature is below 95 degrees F. (35 degrees C.), the plunger in the TVV closes the purge hose between the intake manifold and the canister. Above this temperature, the TVV plunger opens the purge hose. Three check valves are located in the top of the charcoal canister. When the throttle is open enough so the edge of the throttle uncovers the purge port, and the TVV is open, check valve #1 in the canister is opened by vacuum. Under this condition, fuel vapors are purged from the canister through the TVV into the intake manifold. Check valve #2 in the canister is open with pressure in the fuel tank and closed with vacuum in the tank. Check valve #3 operates in the opposite way to check valve #2. A vacuum valve is located in the fuel tank filler cap. This valve opens and allows air into the tank if a specific amount of vacuum develops in the tank.

Bob88GTA

iTrader: (2)

Thanks for the write-up Abu. I had asked that question before on what triggers the operation of the EVAP system. Now I know.

Abubaca

iTrader: (3)

I found that via search, not via direct hands on knowledge, FYI. Words in there like "some" and "often" lead me to believe this is some sort of industry wide way of doing things, but not necessarily EXACTLY how thirdgens operate.

....but it should certainly serve to show what the system is trying to do and when, and provide a baseline gameplan for trying to replicate it.

Bob88GTA

iTrader: (2)

I figured you found it somewhere.
Yes, it tells you what the system is basically trying to do. The reason I asked a while ago was I was reading the several threads on the excessive fuel tank pressure / vacuum issues that so many people experience. I thought that if the EVAP system was working correctly, it could help some of the issues.
But THAT is another box of marbles!