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Thread: EVAP Delete

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    Modfag Saleen4971's Avatar
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    EVAP Delete

    ever want less hoses and crap under the hood?

    well, so do most people.

    DISCLAIMER: SFN and the OP (Saleen4971) take NO responsiblity for any damage to your vehicle, or any legal responsibility if you decide to perform this on a registered road going vehicle. THIS IS MEANT FOR OFF-ROAD USE ONLY. IT IS ILLEGAL TO TAMPER WITH OR REMOVE FEDERALLY MANDATED EMISSIONS EQUIPMENT!

    that being said, i have not performed this as of yet (jeep is down for the count) but i will be doing it very shortly. it HAS however been performed on dakota/durango's with succes.

    ISSUE 1: the PCM throws a CEL when the evap valve is disconnected.
    ISSUE 2: cali emissions vehicles are equipped with a Leak Detection Pump. no way to get around removing this in a cali vehicle. (AFAIK CA, NY, NJ and MA have cali emissions vehicles)


    PROCESS:

    place a breather filter on the evap line that connects the fuel tank to the charcoal canister (located under the drivers side of the front bumper).

    NEXT: remove all of the crap you dont want. aka everything. where the electrical connector is for the evap solenoid/valve/whatever plugged in - simply put a 1/2 watt 100 ohm resister (availabel in a 5 pack for dirt cheap at any radio shack) - make sure you seal it please.

    BAM! you're done - assuming this is a federal emissions vehicle.

    IF YOU HAVE A CALI EMISSIONS ZJ - we will assume that you already run SCT tuning. if not, get it. i dont care what mods you have or dont have. get it. and when you ask for a tune, tell your tuner that you have cali emissions, and you want it written to disable cali. thats it. they will write you a tune that will flash your PCM, and it becomes a federal emissions vehicle. AS FAR AS I KNOW THIS IS LEGAL. cali emissions states allow federal vehicles, given they are a certain age, or have a certain mileage. but DO NOT QUOTE ME ON THAT.

    so there you have it. cali truck? get federal tune, remove evap, place 100ohm 1/2 watt resister in line.

    i will post pics when i end up performing this.

    for now - just to make sure that everyone is clear on what is what, this will also help show you which plug gets the resistor.98zjevap.pdf
    Last edited by Saleen4971; 12-10-2012 at 04:33 PM.
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    Will there be the smell of fuel vapors around the ZJ due to this mod?

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    Modfag Saleen4971's Avatar
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    a little, at times.
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    Forum CONDUCTOR Man Z88Z's Avatar
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    If you left just the cannister and the line going directly to it, do you think it would reduce the fumes at all?

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    RallyJeep GO
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    Probably a little bit, but not much.
    1998 ZJ 5.9 Limited - Deep Slate
    Mods: Big trans cooler, 231 swap, Indy MA-X heads prepped by IMM, Comp 20-744-9 cam, 1.7 HS roller rockers, 52mm TB, Airgap manifold, DT headers and full 3" exhaust, SCT tune homebrewed by me, Martin Saine valve body, B&M tranny pan, magic suspension made from unicorn tears, power steering cooler, lots of lighting mods

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    Quote Originally Posted by Z88Z View Post
    If you left just the cannister and the line going directly to it, do you think it would reduce the fumes at all?
    Doubt it- I removed the cannister on the parts nine, and was going to ship it but it stunk like gas. I think any part of that system vented to the outside will stink. Any reason you couldn't loop that line back into itself?
    -Dave

    1998 GC Laredo SE/1998 Plat 5.9/1998 Plat 5.9/1994 Laredo 5 speed/1998 Slate 5.9- All sold/scrapped

    2004 BMW 330i ZHP- New DD

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    Modfag Saleen4971's Avatar
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    you mean effectively plugging the evap line from the tank? because then you would have pressure issues in the tank - either more pressure when it warms up, or a vacuum from fuel being pulled out, or cooling off.
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    Quote Originally Posted by Saleen4971 View Post
    you mean effectively plugging the evap line from the tank? because then you would have pressure issues in the tank - either more pressure when it warms up, or a vacuum from fuel being pulled out, or cooling off.
    Makes sense.

    What about relocating the charcoal can to underneath the Jeep (like the WJ's have) then running one line back to the engine? Doesn't eliminate the system but makes it look a lot neater.
    -Dave

    1998 GC Laredo SE/1998 Plat 5.9/1998 Plat 5.9/1994 Laredo 5 speed/1998 Slate 5.9- All sold/scrapped

    2004 BMW 330i ZHP- New DD

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    Modfag Saleen4971's Avatar
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    yup. after that thread i started doing some reading, found info on a dakota site.

    i removed most of it last night, will load tune and check it out in the next couple of weeks.
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    i can see deleteing the carbon canister as it take up lots of space but theres really no reason to get rid of the line and purge valve, keeps the CEL off, saves some gas by not letting it evaperate, keeps it smelling good, doesnt hurt performance at all, the valve is smaller than your fist,

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    Modfag Saleen4971's Avatar
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    Removing thibgs underhood is why I did it.
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    Member Paranign's Avatar
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    Nice! consider it done on both my ZJs when I get the time. I will plug the line. I already run a vented gas cap so it doesn't matter.
    94 ZJ Limited - 5.9, Edelbrock headers w/full 2.5" Flowmaster exhaust, Comp torque cam, EQ 1.92 heads, 3.5" lift, Bilstein, OME HD coils, Truetracs F/R, 31" Cooper STT, Galaxy CB, JKS Supernerfs, Mopar efan w/DC Controls box, 242 TC, built trans, 4.10

    95 ZJ Limited - 5.9, 2.5" Flowmaster exhaust, UC, 242 TC, Taurus efan, MX6, mostly stock

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    sfn's lonely vajay jay
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    Bumping this from the dead for some clarification and possible suggestion.

    Hose #1 from gas tank. Was considering maybe looping this guy back into the intake to avoid the gas smell and keep it cleanly vented. If the fumes are combustible, maybe add a one way check valve? Thoughts?

    Hose #2 and #3. From my readings of the system one is for exhaust and one is for intake. For the sake of cleaning up the engine bay I follow these lines up to their location and pull/cap them. Or, another option is to T them together. Any drawback with the T'ing them together?
    Last edited by BoostinChick; 04-19-2015 at 07:29 PM.
    - Sandy

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    im super special x10radsponge's Avatar
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    Thanks for bringing this back. I would love to get rid of the clicking and the reservoir also.

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    Quote Originally Posted by BoostinChick View Post
    Hose #1 from gas tank. Was considering maybe looping this guy back into the intake to avoid the gas smell and keep it cleanly vented. If the fumes are combustible, maybe add a one way check valve? Thoughts?


    Hose #2 and #3. From my readings of the system one is for exhaust and one is for intake. For the sake of cleaning up the engine bay I follow these lines up to their location and pull/cap them. Or, another option is to T them together. Any drawback with the T'ing them together?
    Hose 2 goes from canister to purge valve inlet, hose 3 goes from purge valve outlet to TB (nothing goes to exhaust).


    Looping the tank vent straight into the intake would create a vacuum in the tank when there's vacuum in the intake, and could vent the vapors unfiltered (an air filter won't filter vapors) when the engine isn't running, reverse flowed through the air intake. With the evap system the vapors are only open to the TB when the engine is running, and then only in certain conditions for short durations, controlled by the purge valve.


    On http://thespeedfreaks.net/showthread...highlight=evap one guy mentioned keeping the purge valve but bypassing the canister, running hose #1 straight to the purge valve inlet (deleting hose 2 that usually goes from canister to purge valve) - hose 3 (from purge valve to TB) stays in place. The problem with this is when the purge valve is closed (most of the time) pressure from heat expansion or vacuum from cooling can build in the tank because there's no vent to air. It doesn't really make sense to me to operate a partial evap system - either vent to air or stick with evap.


    I don't mind keeping my evap system in tact, but I need to at least move my canister. I picked up a spare canister, which I planned to crack open, cut down smaller, and plastic weld back together so it can fit inside the fender (behind the driver corner light), or somewhere else. I figure a smaller filter is better than no filter.

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    sfn's lonely vajay jay
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    Function from the FSM
    Quote Originally Posted by FSM
    A maintenance free, EVAP canister is used on all vehicles. The EVAP canister is located below the left front headlamp. The EVAP canister is filled with granules of an activated carbon mixture. Fuel vapors entering the EVAP canister are absorbed by the charcoal granules.

    Fuel tank pressure vents into the EVAP canister. Fuel vapors are temporarily held in the canister until they can be drawn into the intake manifold. The duty cycle EVAP canister purge solenoid allows the EVAP canister to be purged at predetermined times and at certain engine operating conditions.
    So, sounds like a check valve may be a good idea to put on the fuel tank vent line. This way whatever fuel vapors with the fuel tank pressure can be purged, and nothing gets sucked back in. The vapors are sucked back into the intake manifold as per the description which is why I was just going to loop it back to the cold air intake.

    Still debating on whether or not to follow the other 2-lines to the intake manifold and TB and cap them, or use one as a vacuum source for something like a boost gauge.

    For those that like pictures -


    From the diagrams it looks like there are 2-plugs. 1 for the solenoid and 1 for the leak detection pump. Resistor goes to leak detection pump (Item #5 in the original posted diagram) connector?

    P.S. Also reading that this CEL/check can also be removed via SCT. May be a good question for Mr. FlyinRyan as an option for his canned tunes.
    Last edited by BoostinChick; 04-21-2015 at 03:08 PM.
    - Sandy

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    Forum CONDUCTOR Man Z88Z's Avatar
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    Quote Originally Posted by BoostinChick View Post
    ....

    ....Resistor goes to leak detection pump (Item #5 in the original posted diagram) connector?.........

    From the diagrams it looks like there are 2-plugs. 1 for the solenoid and 1 for the leak detection pump. ........

    P.S. Also reading that this CEL/check can also be removed via SCT. May be a good question for Mr. FlyinRyan as an option for his canned tunes.

    No, the resistor goes into the DCPS connector, the one with only two wires. (LDP has 3)

    If it has the LDP it's a CALI PCM, and as Ross said up top the resistor trick will only keep you CEL free if this is a FED PCM ZJ. It will not keep you CEL free if it's a CALI PCM ZJ.

    I'm not sure whether Ryan can actually turn off the CEL for the LDP through SCT or not, but I believe it's less complicated than that. What he can do is to re-write it while he's doing the tune (switch something on/off in his menu?) so that it changes it from a CALI to FED spec PCM. That way it's no longer looking for it's LDP. That might have been what you read, maybe?

    Just for clarification, a CALI PCM will be looking for both DCPS and LDP and will CEL if it doesn't see them. FED PCM is only looking for the DCPS, but the resistor trick will satisfy it. (just FYI stuff: If you put a FED PCM into a CALI ZJ it doesn't "see" the LDP pins so the extra wiring is moot...)



    Good .pdf in Ross's original post, and there's some good comments in the thread Moparr07 linked to in post #9

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    sfn's lonely vajay jay
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    Being on the East coast pretty sure I have a FED PCM. And my reference about the SCT on/off, check box, whatever, was from the Dodge forums where they post that the resistor mod only works for 99 and older. Again, something that can be vetted with Ryan.

    As of right now I am more concerned with my plan for cleaning up the vac hoses and adding the check valve for the fuel vapor and routing it back through the intake. Would be nice to have a dedicated/free port on the intake manifold for the BOOOOST gauge.
    - Sandy

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    Modfag Saleen4971's Avatar
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    a cali PCM can be flashed via SCT with a federal tune - meaning the LDP is no longer an issue.

    - - - Updated - - -

    also - dont use a check valve, and DONT hook up to the intake (re: vent tube from tank)

    the tank has to breathe - as fuel goes out, air must go in. check valve will stop that. also when tank warms up, air goes out, then when it cools (overnight) you will create a vacuum int he tank, which is no bueno.

    vac being no bueno is why you dont want to directly hook it up to the intake (or any vac source)
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    sfn's lonely vajay jay
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    ...filter on the end it is! Are you using one?
    - Sandy

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    Ross nailed it more clearly and with fewer words than I used. Glad we got that cleared up.
    Of course an air filter on the end will prevent crap from getting vacuumed back into the tank, but won't trap the vapors unless it's something fancy with activated charcoal... like an evap canister!

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    sfn's lonely vajay jay
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    You are more than welcome to keep yours! I will be ditching mine, and the spaghetti of tubing, during my battery move effort.
    - Sandy

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    Forum CONDUCTOR Man Z88Z's Avatar
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    Quote Originally Posted by BoostinChick View Post
    Being on the East coast pretty sure I have a FED PCM. ....
    Actually, a lot of states sold new vehicles with CALI spec. I think NY and Mass used them, among others.

    It's not that important since Ryan can knock the CALI out of it, lol..., but you can tell which yours is by comparing it to the .pdf in the first post. If it only has the #1 DCPS piece it's FED. If it has the #s 5 & 9 (LDP and filter and all that) it's CALI.


    Good info from Ross there re the venting.

    You could always just keep the line and run it right to the charcoal canister since the can isn't visible anyway. Bypassing and removing all the EVAP stuff in the process.


    If you're going for max cleanliness and not ever worried about converting it back you could also cut the connectors off (the LDP connector is there whether it's used or not) Add the resistor across the wires there and tape those wires back into the harness. Just be sure to use some heat shrink tubing on the LDP wires and the whole mess, really - especially that orange "on with ignition" wire.

    On my 93 I removed the LDP wires all the way back to the PCM and pulled the pins from the C3. I put the resistor for the DCPS about six inches from the PCM and removed the rest of those wires from there to the EVAP area too. Not really practical unless you're rebuilding your whole harness though - and I really don't recommend that!

    Last edited by Z88Z; 04-23-2015 at 07:34 AM.

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    Quote Originally Posted by Z88Z View Post
    On my 93 I removed the LDP wires all the way back to the PCM and pulled the pins from the C3. I put the resistor for the DCPS about six inches from the PCM and removed the rest of those wires from there to the EVAP area too. Not really practical unless you're rebuilding your whole harness though - and I really don't recommend that!

    I've done SO many things I wouldn't recommend, but once you get started you can't just stop and change your mind! When I start my OCD SC build thread (soon), you'll see what I mean.

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