Marc in az

So it took me a year to get it all ironed out and I learned a lot so I thought I would pass it to all my jeep buddies who will be having this problem.

When it came time for emissions I failed with all sorts of codes. Misfire codes, large leaks, small leaks, etc. I thought emissions was very technical ad hard but slowly I wasted time looking. So lets get to brass tacks......

If you have all those codes, especially the misfire code, don't waste time with gas caps and spark plugs (my jeep has 334.000 miles). go straight for a leak down test and compression test. Both are actually quite easy and plenty of how-to's on youtube. In my case, I failed the leak down test as the compressed air went right out the tail pipe. (exhaust valve was toast cylinder 1.
Got the head rebuilt and took a complete day to change out the head but I got it done. I used a permatorque head gasket by felpro and it works absolutely amazing.
So after replacing the head ran the OBD check and had P0441, P0456 etc. Small emission leaks. I wasted many hours listening to stupid advice, tricks and looking at hoses. If you have an old jeep like mine , do this : in the engine compartment replace every emission line and elbow that you can get your hands on. The leak detection pump and the purge solenoid and cheap enough. Toss them out and put in new ones. Who cares if they work! they're old as F___, just toss them out. lol Next, drop the tank. It literally takes ten minutes to drop the tank so just drop it and replace the rollover valve. I had to drill mine out with a hole saw because on a 2001 it is bonded to the tank. I used quiksteel tank repair and that shizzle works awesome. I dropped in another rollover valve. Check to make sure the fuel pump screw collar is tight or replace the gasket even better. replace the filler neck hoses and inspect the filler neck. I noticed a good size crack on the inside which I repaired with the quiksteel. replace all the elbow and lines going to the charcoal cannister. And lastly, there is one line that goes from the cannister to the leak detection pump. It's rubber then plastic then metal then rubber again. Get rid of it. Keep only the first section of vacuum line coming from the cannister. I bought 6 ft of 1/2 in heater hose and attached from under the jeep, between the firewall and engine and directly across to the LDP (leak detection pump) . And don't bother testing the cap (if its the original). Just toss it out, get a new one.

As of yesterday, 0 codes, green light. (and took 4 days to get through the drive cycle.) Passed emissions and it runs great. In my quest to solve misfire problems I also changed the spark plugs, fuel injectors (4 hole upgrade) , coil pack and the grommets on the valve cover .
Also study your emissions diagrams. It's really not that complicated to figure out. If I had done it that way from the beginning it would've only taken me a few days. ha . Feel free to ask questions.

Marc

Silver01Bullet

Marc,
The evap hoses that are connected to the charcoal canister on my 2001 are needing replaced. Where did you get yours, or did you use a different type hose?

Gotyoulooking

same here, been looking for the rubber part that attaches to the canister to the line coming from the front for ever. Damn thing is different diameter on both ends.

Silver01Bullet

I'm sure it can be done with a few pieces of hose and maybe some fittings, or even stretch/boil some. I have called one of our local dealers, one of the largest in the country, and they say the hoses seem to be NLA. I may just crawl under it and mic the lines and see what I can come up with

TheBoogieman

Jeep stealership or junk yard.

Gotyoulooking

tried the one by me but they only have the whole assembly, go figure.

Silver01Bullet

So, after measuring the lines and nipples at the charcoal canister, I went to the parts store and got a few pieces of fuel line, in different sizes. Went to Westlake and got a few brass fittings (barbed), put them together, clamped the lines to the fittings. In the process I went and bought a smoke tester off ebay. Hooked up the smoke tester, and found no leaks apparent. Had the wife scheduled to bring the Jeep to work today to clear the check engine light, she pulled in the lot and informed me that the light had went away. Hooked up the Snap-On scanner and showed no codes. I'm good with that for now, we'll see what happens from here.