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Topic Review (Newest First)
09-30-2011 02:52 AM
2xs Rule of thumb:
You vehicles model year or newer, and it has to have been an option for your model year.

Since the 4.0L was a stock option you should be ok putting a 4.0L in your Wrangler
You should still check with your local emissions inspection guys, but all that information should be available on your states DMV website.
09-30-2011 02:14 AM
Xpress Go down to your DMV and ask to speak with a smog referee. I know California requires that you get the swap legalized before a smog shop will touch it, and that requires some fees and a very scrutinized inspection by a smog referee. It only takes one thing and they will fail you.

If you pull a 4.0 with ALL of the emissions equipment, and get a good cat and new sensors, then there's no reason it won't pass smog. Vehicles have to pass emissions testing from the factory since 1974.
09-30-2011 12:48 AM
DamnBigPapa Some counties have some strange regulations. Dont "assume" what's coming out the pipe is the only factor. Better safe than empty pockets. I'd ask
09-29-2011 01:37 PM
ninja07 Thanks for the input everyone. I'll check what the hydrocarbon limit is for my engine and year jeep, and the average output of the 4.0. If nothing else, I guess I can always run two catalytic converters to filter out a little more.
09-28-2011 04:19 PM
DamnBigPapa Don't take anyone's word for it. Go talk to the folks at the DMV testing facility. Not the yahoos at the local Jiffy Lube, each county should have an official county facility.
09-28-2011 02:29 PM
XJ Knight
Originally Posted by schnutzy View Post
this is false. it is a state by state thing.
Awesome thanks derek.. Now I know for sure..
09-28-2011 02:27 PM
Originally Posted by XJ Knight View Post
Engine going in needs to be the year of the vehlicle it's going into or newer.. I think thats federal law and not state to state but someone here can verify that
this is false. it is a state by state thing.
09-28-2011 02:06 PM
XJ Knight Engine going in needs to be the year of the vehlicle it's going into or newer.. I think thats federal law and not state to state but someone here can verify that
09-28-2011 02:02 PM
Leans93 I'm in AZ but I swapped a 2.5L for a 4.0L and I pass emmissions every time. You should be fine if you do it right.
09-28-2011 01:24 PM

09-28-2011 01:16 PM
2.5 swap 4.0 still pass emissions?

I've got a 1994 YJ w/ a 2.5. I was wondering if I swapped a 4.0 in it, would it still pass emissions. I'm in Nashville Tennessee, so 1995 and older only has the tailpipe only test. But would it create too many hydrocarbons, monoxides or dioxides or whatever? If anyone has already encountered this dilemma, any advice would be appreciated. Thanks,

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