Rednroll

Well, maybe I lucked out. So far no CEL. A couple weeks ago, I tried tightened my gas cap multiple times, made sure things seemed cleaned and reset the CEL and after 3 attempts of that, the CEL came back on within 15 minutes. Today I've driven for close to 2 hours and no CEL after reconnecting the hose.

By the same guy in the above video he explains in the video below of how to use an OBD2 scanner in Mode 6 to do some further inspections. I'll get my BlueDriver scanner out tomorrow on my drive to work and see if I can get the same type of Mode 6 data to see where my readings are now, and then disconnect that hose again and see if the readings change.

And since these evap leaks seem to be a pretty common problem on our JK's with multiple points of failures, I decided to go ahead and invest in an budget smoke tester. This one seemed like a pretty good value and doesn't look like a modified paint can compared to all the others in its price range.
https://www.carsmoketester.com/produ...er-evap-vacuum



Currently $82 for the black one, then use promo code "Youtube" to get an additional $10 discount. Free shipping and no tax as well.

LC Boyer

Let us know how you come out!

Rednroll

Does anyone know if the JK has a EVAP service port anywhere? It should be a valve stem with valve core with a green cap on it. Apparently that's what can be used to perform a smoke test. I looked in the engine bay and couldn't find anything with a green cap on it. Only black cap A/C service ports. I haven't crawled underneath to look for it.

Rednroll

My CEL for a P0456 came back yesterday on the drive home from work.

In this post, they mention doing a smoke test and observing smoke coming out of the oil fill cap, replaced the cap and seems to have fixed their problem.
https://www.jk-forum.com/forums/stoc...k-code-338847/

Which leads me to believe that if a non air-tight oil fill cap could cause the problem, then it would make sense that if my valve vent hose was disconnected then that should cause the same as a leaky oil fill cap since they're both essentially a hole in the same valve cover. Heck, a leaky valve cover gasket could cause it. That's why I'm thinking investing in a smoke machine seems like a good idea to help take the guess work out of it. Same reason to purchase a pressure tester when you have a coolant leak.

I put silicone grease around my gas cap seal, and reset the CEL, expecting the P0456 to come back.

Here's what my Mode 6 test showed after the CEL came back on.


In regards to performing a smoke test after the smoke machine arrives, so far I haven't been able to get a good answer on how and where to connect the smoke machine to the evap system. However, it seems disconnecting the purge valve and connecting to each of the vacuum lines which connects to it seems to be the way to go. One vacuum line should run towards the back to the gas tank, and the other vacuum line connects to the intake manifold.

I'm learning more about the evap system and here's how I think the flow of the evap system goes where there could be a small leak anywhere along this path.

REAR of JK [Gas Cap>Gas filler neck>Gas Tank>Gas Tank Vapor lines>Vapor Canister/Vapor Canister leak Detection Pump assembly> vacuum line up to engine bay]
UNDER HOOD of JK [vacuum line from rear>Purge control valve/switch>Upper Intake Manifold>Valve covers/Oil Fill cap/Valve Vent hose>Air filter box]

So essentially a leak anywhere along that entire path of hoses, connections, or parts could cause the code to be set.
Is there a diagram of this system for our JK's anywhere?

This weekend I will disconnect the purge control valve and do the blow test on the valve to determine if that is the problem or not. Then move on to a smoke test while I have that off and have access to the vacuum hoses that connect to the purge valve. I doubt the smoke machine will be here by this weekend to perform the test but eliminating the purge valve should be a good start to diagnosing this.

Rednroll

Just an FYI, to let others know. The company selling the smoke tester listed above no longer seems to be shipping the product. I waited over a month to receive and didn't. I reached out to their multiple email, and live chat services and received no responses. I now need to contact my bank to see if there's anything I can do to get my money back. What a headache!

That smoke tester was reviewed in the below youtube video and others have mentioned in the comments, that they have not received their orders placed in within the last month or so as well.

This is the reason I typically shop on Amazon and Ebay but couldn't find this smoke tester there and against my better judgement went through the website. With Ebay or Amazon, if this type of sh*t happens I know I would get my money back.

Agua

Did you ever end up finding an evap service port on the Jk/ testing through the purge valve? I’m having the same issue and have a smoke machine so want to hook it up and test cause I’ve already replaced half of the evap system with no luck of getting rid of the leak! And can’t find any diagrams or videos of anyone actually smoke testing the JK.

Rednroll

After reading multiple discussions on this topic, people said they performed a smoke test but never responded to my question of where they connected to run the smoke test. It seemed to be discussions where they joined the forum, reported their problem, got their problem fixed and were never before seen from again.

Anyways, I've become more familiar with the entire system while looking into it, and disconnecting the purge valve and running the smoke test into each of the 2 tubes the purge valve connects to, seems to make the most sense to me. I never did receive my smoke tester. The company took my money, closed shop, and could never be reached afterwards.

I ended up throwing parts at it instead.
- Started by 1st checking the purge valve by disconnecting it and trying to blow through it. (everything checked out ok...I couldn't blow through it).
- Then replaced my gas cap (52030387AB), reset the code, ran for 2 days and CEL came back.
- Then I replaced the Fuel Vapor Canister Leak Detection Pump (4861962AB) and its gasket (52129436AA). It's now been 2 weeks and the CEL has not come back on. Cross my fingers, but so far I think that was the fix for me.

So replacing this part and its gasket seems to have worked for me. The most important for me, was that it is now cold in my area and when the CEL is on, your remote start will no longer work and that sucks in my area once you've grown accustomed to using remote start in the winter.

Agua

Hey RednRolll Thanks for the detailed response!
I ended up doing the same thing by disconnecting the purge valve and smoke testing each line! I ended up finding the hose that pulls vacuum going into my BOV which had a very small leak ( its supercharged which just has made everything more difficult lol). Im sorry to hear about your smoke tester luck! companies like that make me sick. If it makes you feel any better I had already replaced my MAP sensor, evap cannister, gas cap, gas cap seal, leak detection pump and its gasket lol.

I couldn't find anything else but havent had anymore evap codes just my catalyst efficiency "Permanent" code but that led me to find that my brand new High flow cats that came with my new BBK long tube headers had completely blown out and plugged my muffler. so now am trying to figure out if i can get another set of Cats(which im worried of even putting back on) and already had to buy a brand new muffler to replace my gibson exhaust.

so now going to replace with same or different Cats, rear exhaust section and then going to get a custom tune because right now my motor is falling on its face around 4000 rpm im guessing because of false readings from the 02 sensors due to lack of Cats but im no expert.

I wonder if anyone has added on an evap test port to an existing line? it would make future tests much simpler and i couldnt imagine would be that difficult.