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Where can I find a vacuum line diagram?

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My truck failed an emissions test the other day because of high Nox so I am looking into the EGR system. I replaced the vac hoses and tested the EGR valve by applying vacuum directly to it and it moves properly.


Were can I find a good diagram for the vac lines to verify if mine are right?


Is there anything else I should be checking that could cause high Nox? The Jeep was overheating during the test, can that cause high Nox? I'm replacing the radiator next week since it recently started leaking slightly and hopefully that will fix the heat issue.

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For a 4.0 L



For a 2.5



I've heard that it's entirely possible to delete the EGR altogether, but I don't know how and/or if it's legal where you live. I failed miserably 5 years ago and so I'm really anal about it. Frankly I don't know what causes NoX, HC or CO getting out of whack, so I just make sure everything is clean and tight.


I know it's probably unnecessary but my checklist for smogging my XJ every 2 years is:


Change oil

Plugs, wires, rotor, regular tune-up

New O2 sensor, yep, every 2 years. $50 worth of insurance.

NEW gas cap.

Check and replace (not duct tape) any suspicious vac lines.


...and a can of G2P...follow instructions on container.

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