Conversions & Swaps LSX Engines in Non-LSX Vehicles
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Old Feb 2, 2016 | 08:38 AM
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Default Evap System

I have a 98 Wrangler with a 4.8 4L60. Bought it as a bunch of parts and finished the project. The p/o had the EVAP removed from the swap harness and deleted from PCM. The tank is stock jeep with the Novak FPR modification to support the GM pressure. The Jeep evap canister is intact and located in the engine bay, but the engine side of the purge valve is currently blocked off.

On longer drives and warmer days, especially with a full tank, the fumes will overcome the canister and its gets pretty unpleasant in the cab. The inspections here will not notice whether or not the canister is there, but I do want the fumes addressed for my own benefit.

Is there a simple way to have the GM ECU fire the jeep purge valve? Any other simple ways to fix this?
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Old Feb 3, 2016 | 06:06 AM
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Old Feb 6, 2016 | 09:22 AM
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I am doing a swap on a 76 c10 my self that will need a smog inspection. When I had my processor tuned and emissions monitoring turned off it was explained to me that the system still functioned but did not run the monitor so the check engine light would not come on. You may just need to plumb the purge valve up and let it run as designed. I want the evap to function on my set up as well to reduce the fumes. good luck and post back with what you find.
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Old Feb 8, 2016 | 03:28 AM
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Originally Posted by A-Dub
I have a 98 Wrangler with a 4.8 4L60. Bought it as a bunch of parts and finished the project. The p/o had the EVAP removed from the swap harness and deleted from PCM. The tank is stock jeep with the Novak FPR modification to support the GM pressure. The Jeep evap canister is intact and located in the engine bay, but the engine side of the purge valve is currently blocked off.

On longer drives and warmer days, especially with a full tank, the fumes will overcome the canister and its gets pretty unpleasant in the cab. The inspections here will not notice whether or not the canister is there, but I do want the fumes addressed for my own benefit.

Is there a simple way to have the GM ECU fire the jeep purge valve? Any other simple ways to fix this?
If it were me, I would plumb the vent line from your tank to your induction after your air filter/MAF, but before the throttle body. I would use small hose (1/4" or smaller) to do it, since you won't need much flow to eliminate the fumes. Would also enlarge the vent on your gas cap a bit, in case your air filter gets a bit plugged, you don't put vacuum on your fuel tank.
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