Snowboarder12345 Posted June 19, 2017 Share Posted June 19, 2017 Anyone ever deleted their charcoal canister and not had the CEL come on? My idea is to splice resistors into the wiring harness to mimic the signals that the sensors would send back to the ECU, but I'm wondering if perhaps there is a simpler way. I want to get rid of it because it's just one more thing to fail, and I could see it perhaps letting water into my fuel system down the line should I ever get adventurous. Link to comment Share on other sites More sharing options...
fixinto Posted June 20, 2017 Share Posted June 20, 2017 as far as i know, there is a signal to open the EGR valve and as long as it opens when the ECU tells it to you are ok. Don't think a resistor will work since it is looking for a response from a component. Link to comment Share on other sites More sharing options...
rc_cola_j Posted June 25, 2017 Share Posted June 25, 2017 Anyone ever deleted their charcoal canister and not had the CEL come on? My idea is to splice resistors into the wiring harness to mimic the signals that the sensors would send back to the ECU, but I'm wondering if perhaps there is a simpler way. I want to get rid of it because it's just one more thing to fail, and I could see it perhaps letting water into my fuel system down the line should I ever get adventurous. You're asking about the EVAP system right? Not the EGR? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Slartibartfast Posted June 25, 2017 Share Posted June 25, 2017 If anything, I'd expect the evap system to make it harder for water to get into the tank vs having just a vent on it. Plus it means you don't smell gas around the truck unless there's a leak. Link to comment Share on other sites More sharing options...
rc_cola_j Posted June 25, 2017 Share Posted June 25, 2017 If anything, I'd expect the evap system to make it harder for water to get into the tank vs having just a vent on it. Plus it means you don't smell gas around the truck unless there's a leak. When I was tracking down my rough idle issues, one of the things I did was disconnect the EVAP sensors and hoses to the canister. I drove around for a few weeks like this and oddly enough, I threw no codes. My rough idle didn't change, and yes, you could smell gas around the vehicle......why no codes though? Sent from my iPhone using Tapatalk 1 Link to comment Share on other sites More sharing options...
clkindred Posted June 25, 2017 Share Posted June 25, 2017 I half deleted mine after it sent charcoal through the evap lines all the way to the intake, plugged up the lines solid. After blowing out the charcoal out of the lines and tapping on the canister until it was empty, I put it all back together. The system does a self test periodically to check for leaks by letting the intake pull a vacuum on the system, if there is a leak like a bad gas cap seal, or something else it will cause a SES light and a code. I'm not sure if it does this test every run cycle or every number of them, but before I discovered the charcoal problem, clearing the code would have it stay gone for a while, a few days to up to a week. This made me think several times the problem was gone, only to have the code come back. Perhaps only certain conditions like high engine RPM allow the self test to happen, so with easy driving you could dodge a code maybe? I can't recall all the components sending signals to the ECU in the system, but I think there are at least 3 valves and a vacuum sensor to deal with. The signals are not constant, such that the ECU only looks for the vacuum signal when the self test is commanded. There is also a vacuum cut valve that shuts the system off from the intake during engine start so it dose not provide a vacuum leak. I also believe it monitors the state of the valves so if one sticks it throws a code. Much more than I wanted to try to spoof, so I reinstalled everything and the whole system works like it should, only with no charcoal to adsorb fuel vapors. No codes since. 1 Link to comment Share on other sites More sharing options...
Snowboarder12345 Posted June 25, 2017 Author Share Posted June 25, 2017 If anything, I'd expect the evap system to make it harder for water to get into the tank vs having just a vent on it. Plus it means you don't smell gas around the truck unless there's a leak. Every breather line on the vehicle is going to end up high in the roof. I was thinking some sort of check valve to stop fumes from getting out but to still allow air to enter the tank as fuel is consumed. Link to comment Share on other sites More sharing options...
Snowboarder12345 Posted June 25, 2017 Author Share Posted June 25, 2017 I half deleted mine after it sent charcoal through the evap lines all the way to the intake, plugged up the lines solid. After blowing out the charcoal out of the lines and tapping on the canister until it was empty, I put it all back together. The system does a self test periodically to check for leaks by letting the intake pull a vacuum on the system, if there is a leak like a bad gas cap seal, or something else it will cause a SES light and a code. I'm not sure if it does this test every run cycle or every number of them, but before I discovered the charcoal problem, clearing the code would have it stay gone for a while, a few days to up to a week. This made me think several times the problem was gone, only to have the code come back. Perhaps only certain conditions like high engine RPM allow the self test to happen, so with easy driving you could dodge a code maybe? I can't recall all the components sending signals to the ECU in the system, but I think there are at least 3 valves and a vacuum sensor to deal with. The signals are not constant, such that the ECU only looks for the vacuum signal when the self test is commanded. There is also a vacuum cut valve that shuts the system off from the intake during engine start so it dose not provide a vacuum leak. I also believe it monitors the state of the valves so if one sticks it throws a code. Much more than I wanted to try to spoof, so I reinstalled everything and the whole system works like it should, only with no charcoal to adsorb fuel vapors. No codes since. This is good to know, thanks! Maybe I will just reinstall it all then, but plumb the breather up higher and wait for it to fail and decide then. I was mostly worried about it failing and putting me into limp mode when I'm out into the bush somewhere. Link to comment Share on other sites More sharing options...
Slartibartfast Posted June 25, 2017 Share Posted June 25, 2017 I could be wrong but I don't think the evap system is essential enough to trigger limp mode. 1 Link to comment Share on other sites More sharing options...
rc_cola_j Posted June 26, 2017 Share Posted June 26, 2017 I half deleted mine after it sent charcoal through the evap lines all the way to the intake, plugged up the lines solid. After blowing out the charcoal out of the lines and tapping on the canister until it was empty, I put it all back together. The system does a self test periodically to check for leaks by letting the intake pull a vacuum on the system, if there is a leak like a bad gas cap seal, or something else it will cause a SES light and a code. I'm not sure if it does this test every run cycle or every number of them, but before I discovered the charcoal problem, clearing the code would have it stay gone for a while, a few days to up to a week. This made me think several times the problem was gone, only to have the code come back. Perhaps only certain conditions like high engine RPM allow the self test to happen, so with easy driving you could dodge a code maybe? I can't recall all the components sending signals to the ECU in the system, but I think there are at least 3 valves and a vacuum sensor to deal with. The signals are not constant, such that the ECU only looks for the vacuum signal when the self test is commanded. There is also a vacuum cut valve that shuts the system off from the intake during engine start so it dose not provide a vacuum leak. I also believe it monitors the state of the valves so if one sticks it throws a code. Much more than I wanted to try to spoof, so I reinstalled everything and the whole system works like it should, only with no charcoal to adsorb fuel vapors. No codes since. Where did you disconnect the EVAP line to find the plug? Was it where the EVAP line comes into the engine bay (driver's side)? Link to comment Share on other sites More sharing options...
hawairish Posted June 26, 2017 Share Posted June 26, 2017 I had a similar issue as Clkindred on my 98 Frontier where the canister ruptured and sent charcoal all the way to the engine bay. PITA. Rebuilt a solenoid, replaced all hoses, and had to blow/vacuum the hardlines to clear the crap. Fortunately, someone shed light on a $30 Maxima canister that was just a reverse of the $130 Frontier one...rigged it up properly, cleared all my codes. Frontier uses the same solenoid as my truck; helpful for diagnostics. Given that experience, the EVAP system seems far too delicate to mess with. I don't believe it can trigger limp mode (didn't on my Frontier, but it's a far car from the sophistication of the R50), but it seemed to degrade performance on the truck. I'd say if you can avoid messing with it, do. Link to comment Share on other sites More sharing options...
Citron Posted June 26, 2017 Share Posted June 26, 2017 Just curious, how would it degrade performance? It's only purpose is to catch gas fumes from the tank. Link to comment Share on other sites More sharing options...
hawairish Posted June 26, 2017 Share Posted June 26, 2017 Not sure exactly, and I agree with your reason for asking. The canister has the function of trapping fumes, but I'm not sure if the clogged-open purge solenoid changes anything about the fuel pressure once the engine is warmed up and vapors cleared. I wouldn't think there's a correlation either, but this is an observation from driving 150 miles in this condition and it couldn't accelerate past 75mph. Condition cleared, no hiccups getting up to 90mph. The only difference was changing the EVAP can, clearing the lines, fixing the solenoid, putting a clear fuel filter by the can to prevent this from happening again, and resetting the ECU. Not sure what else could have contributed to the poor performance. 1 Link to comment Share on other sites More sharing options...
Citron Posted June 27, 2017 Share Posted June 27, 2017 Very interesting. I wonder why... Link to comment Share on other sites More sharing options...
Slartibartfast Posted June 27, 2017 Share Posted June 27, 2017 If it's trying to apply a vacuum to the canister, and the canister's not sealed, you'd have a vac leak messing with your fuel mix. That's the best I can think of. Link to comment Share on other sites More sharing options...
Exorpmtech Posted June 28, 2017 Share Posted June 28, 2017 (edited) The system checks for a change in the tank/evap system vaccum while driving. It has a purge valve that allows the engine to pull vacuum on the system while driving and vent/evap solinoid to close the system allowing it to build negative pressure. You could fool the computer by installing resistors in place of the solinoids but you'd have much more difficult time fooling the vapor pressure sensor that monitors evap/tank pressure. It has to see a rise in vacuum and then a decrease within a specified time constraint. Edited June 28, 2017 by Exorpmtech 2 Link to comment Share on other sites More sharing options...
clkindred Posted June 30, 2017 Share Posted June 30, 2017 Where did you disconnect the EVAP line to find the plug? Was it where the EVAP line comes into the engine bay (driver's side)? Yep, drivers side kinda behind the throttle body if memory serves. Pulled the little hose off the barb and charcoal came out. Link to comment Share on other sites More sharing options...
rc_cola_j Posted June 30, 2017 Share Posted June 30, 2017 Yep, drivers side kinda behind the throttle body if memory serves. Pulled the little hose off the barb and charcoal came out. I'm gonna go check mine. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now