Building an EVAP System
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On The Tree
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Building an EVAP System I don't have any provisions for wiring in an EVAP system in my harness I got from Speartech for my Gen 5 L83/6L80 that I have swapped into a Land Rover Defender. I don't need the test function to work but I'd like to get the purge solenoid to work and keep the fuel vapors from building up, these things are notorious for leakage so I'm guessing any vapors would work there way into the cabin.
So far as I understand is I'll go from my fuel tank to the canister to the purge valve and also have a rollover valve coming off the canister. Now to get it to work I was looking over the E92 pin outs and I could only see two for EVAP. One for vent solenoid which I don't think I need as it will remain open when no power. The other is the purge solenoid. I can't run a scan on my ECU yet as my wiring isn't done, so I just downloaded one from my Gen 4 LS Jeep JK so I could start poking around. I'm using HPTuners but I'm new at that and I can't find anything that looks like it would control the purge valve.
I thought I read that the pin will provide a ground ref to open the solenoid but I don't know where to go from here and would appreciate some help. I know I can just block it off but I don't want to.
Thanks in advance,
Sean
So far as I understand is I'll go from my fuel tank to the canister to the purge valve and also have a rollover valve coming off the canister. Now to get it to work I was looking over the E92 pin outs and I could only see two for EVAP. One for vent solenoid which I don't think I need as it will remain open when no power. The other is the purge solenoid. I can't run a scan on my ECU yet as my wiring isn't done, so I just downloaded one from my Gen 4 LS Jeep JK so I could start poking around. I'm using HPTuners but I'm new at that and I can't find anything that looks like it would control the purge valve.
I thought I read that the pin will provide a ground ref to open the solenoid but I don't know where to go from here and would appreciate some help. I know I can just block it off but I don't want to.
Thanks in advance,
Sean
Last edited by sgo70; Mar 6, 2021 at 09:01 AM.
My suggestion is that you find out everything that you can about how the vehicle EVAP system actually worked and maybe also find out how a GM system works. In broad strokes, there is a purge solenoid and also a fresh vent solenoid. There is also a pressure sensor in the system that is used for diagnostics. If you go on youtube there are numerous videos that you might find helpful.
Andrew
Andrew
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On The Tree
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Yeah I've been reading a ton but the problem is I can't seem to find any information about what signals the purge solenoid to open. I was starting to think that I might just wire it in to the start circuit so it would close the circuit and purge whenever I started the truck. The stock system should only purge between 15-85% fuel in the tank but I think adding that might get a bit too complicated. I can't for the life of me figure out the wiring, I've tried to find something on the LS even to give me somewhere to start looking. Speartech built my harness so I might call them on Monday to see if they can give me any info, they've been quite helpful whenever I call them.
Sean
Sean
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I found this:
The PCM energizes the canister purge solenoid and allows vacuum to purge vapors from the canister under these conditions:
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.
Still can't figure out how the ECM signals this though.
Sean
The PCM energizes the canister purge solenoid and allows vacuum to purge vapors from the canister under these conditions:
- 150 seconds have elapsed since the PCM entered closed loop.
- Coolant temperature is above 176 degrees F. (80 degrees C.).
- When the PCM is not enabling injector shut-off, such as on vehicles with traction control while one drive wheel is spinning.
- The idle contact switch in the IAC motor is open.
- Vehicle speed is above 20 mph.
- Engine speed is above 1,100 rpm.
- The engine metal temperature sensor is not indicating excessive temperature.
- Low coolant level is not indicated.
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.
Still can't figure out how the ECM signals this though.
Sean
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From: Montgomery (Lake Conroe,) TX north of Houston
Thanks for posting all of that information. This topic seems to be pretty popular but no one seems to have all of the information, i.e. how long does the ECM purge the system? How often during a drive will the ECM purge? I'm planning on using the OEM Ford EVAP system on my LS swapped Fox body Mustang.
Last edited by dannyual777; Mar 6, 2021 at 07:53 AM. Reason: I noticed some random symbols that ls1tech added. I removed them.
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I found this:
The PCM energizes the canister purge solenoid and allows vacuum to purge vapors from the canister under these conditions:
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.
Still can't figure out how the ECM signals this though.
Sean
The PCM energizes the canister purge solenoid and allows vacuum to purge vapors from the canister under these conditions:
- 150 seconds have elapsed since the PCM entered closed loop.
- Coolant temperature is above 176 degrees F. (80 degrees C.).
- When the PCM is not enabling injector shut-off, such as on vehicles with traction control while one drive wheel is spinning.
- The idle contact switch in the IAC motor is open.
- Vehicle speed is above 20 mph.
- Engine speed is above 1,100 rpm.
- The engine metal temperature sensor is not indicating excessive temperature.
- Low coolant level is not indicated.
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.
Still can't figure out how the ECM signals this though.
Sean
I don't remember where I saw it, but I recall that the ECU grounds one pin of the solenoid, while the other pin has switched power.
Your description about is very helpful, but it doesn't mention the vent solenoid, which I believe most new systems utilize. The other things that your description doesn't mention is how often it purges. As I understand it, there is not need for the purge solenoid to be active all the time. It usually only needs to purge once per drive cycle.
Andrew
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Thread Starter
On The Tree
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Thanks, I fixed it so I don't mislead anyone.
I think it's pin 51 on the x2 black plug for the purge, I also think I read it gives a ground.
I also understand the vent solenoid is always open and only needs to be closed for testing which I can live without, I guess if I can figure out the purge then I can probably figure out the vent as well. Gonna have to figure out the fuel tank pressure sensor as well I guess.
Sean
I think it's pin 51 on the x2 black plug for the purge, I also think I read it gives a ground.
I also understand the vent solenoid is always open and only needs to be closed for testing which I can live without, I guess if I can figure out the purge then I can probably figure out the vent as well. Gonna have to figure out the fuel tank pressure sensor as well I guess.
Sean
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On The Tree
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Just another update, I just found this:
"Purge valve - don't plug it in. Disabled. Then as previous poster said check for codes. Which ever coded are logged for it then disable with 3-no report
There is not magical on/off for every sensor on car. They all rely on unplugging and setting codes correctly to disable them."
I can't imagine it would be that simple that I just plug the pin in and it will magically work haha. After 3 days of searching that would be kinda funny.
Sean
"Purge valve - don't plug it in. Disabled. Then as previous poster said check for codes. Which ever coded are logged for it then disable with 3-no report
There is not magical on/off for every sensor on car. They all rely on unplugging and setting codes correctly to disable them."
I can't imagine it would be that simple that I just plug the pin in and it will magically work haha. After 3 days of searching that would be kinda funny.
Sean
