Removing Emissions? - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 12-11-2001, 04:44 PM Thread Starter
Join Date: Oct 2001
Posts: 409
Thanks: 0
Thanked 0 Times in 0 Posts
Removing Emissions?

I have done a few searches and can not find pin pointed what i am looking for.

When you remove the emissions from a 4.2, what do you remove and how?
To get rid of the computer controled items, how do you do that and what do you replace them with?
When can i get my hands on Holley TBI for the 4.2? How much?
Any other tricks to get it running excelent???

Headed for Gunnison, soon....

87Warrior is offline  
Sponsored Links
post #2 of (permalink) Old 12-11-2001, 05:30 PM
Way Outta Control
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
Re: Removing Emissions?

1. Emissions are controlled by the ECM (computer behind the glovebox).
2. Remove the ECM and the emissions are brain dead and you can remove the emission vacuum lines and devices...
3. Removal of the Computer is accomplished by doing the Nutter bypass. (do a search on Nutter Bypass)
4. The Nutter bypass ties the ignition module straight to the distributor.
5. Look into the 4.0L head swap and an Webber or MC2100 carb.
6. See if you'd like to do a Junkyard GM TBI swap.
7. EFI alternitives:
a. Junkyard 4.0L engine.
b. Hesco/Mopar SMPI.
c. Howell TBI.
d. Holley TBI.
e. Turbo City TBI.

LEVE is offline  
post #3 of (permalink) Old 12-12-2001, 07:04 AM
I Might Just Know What I'm Talking About
Pete88YJ's Avatar
Join Date: Sep 1999
Location: BOSTON
Posts: 1,748
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Removing Emissions?

I'm surprised LEVE didn't say more about WHY you want to do this? [img]/wwwthreads_images/icons/wink.gif[/img] I think he's slipping. [img]/wwwthreads_images/icons/wink.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img]

The main goal is to have a Jeep that runs well, AND keeps our air fresh. We all have to breathe. [img]/wwwthreads_images/icons/cool.gif[/img]

Yes, the existing system on 87-90 YJs is troublesome, BUT there's no reason to just dump everything because it's "emissions stuff". [img]/wwwthreads_images/icons/crazy.gif[/img] A closed loop injection system is probably best, as it proably will make your jeep run the cleanest at all times, hot, cold, etc. If you don't like injection, or just don't have the $ for it, there is a lot you can do, and still stay clean.

Lose the BBD, go to a simple carb. There are a few options. I have the weber. Go to a better, simpler, ignition. I like the GM HEI. Most here seem to favor the TR upgrade. Be sure that your advance curve is correct for your engine - this has a lot to do with what your emissions are.

I took out the pulse air system and it's associated pipes, and the 3 solenoid things on the rear of the valve cover. Keep the EGR, as it will lower your NOx emissions. Keep the PCV. Keep the cat, as it lowers your emissions. Generic-fit cats be had for like $40 now. Go with a high-flow cat if you think the stock one will rob you of power. (I think this is a myth personally - a stock one is fine for a jeep, in my opinion.) Change your plugs, wires, cap, rotor, etc., on a regular basis. Check that your choke is operating properly. Most poorly running and polluting jeeps, in my opinion, are simply due to a lack of maintenance.

With all that said, my Jeep passes the new dynometer sniffer here in Massachusetts. [img]/wwwthreads_images/icons/smile.gif[/img] First time I went in my EGR valve was bad (I had no idea), and it had high NOx. I replaced it and passed no problem.

Not saying that you will pass if you do what I did, or if it's legal for you (my state has no visual, it's just gotta pass the sniffer).

Perhaps TR will chime in with his thoughts. He's much more knowledgeable than I.

Just my $0.02
Good luck

"Everything I've got to offer, girl, is beneath this dirty hood." -- Bruce Springsteen.
Pete88YJ is offline  
Sponsored Links
post #4 of (permalink) Old 12-12-2001, 07:44 AM
Way Outta Control
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
Re: Removing Emissions?

Hey Pete... Me Slipping? Nah, I'm starting to think though I don't have Alzheimer’s I can at least start selectively remembering stuff. I've been doing it with the Wife and Kids for years and it's been ever so successful.

Geezz, even less attractive girls are gettin' prettier the older I get. I think I'm getting to like the "golden years"....

In all seriousness, I though I was slippin' when I read your excellent follow up.... but then I re-read the 87Warrior’s post... The question of <font color=red>Why?</font color=red> was never asked and I assumed that 87Warrior knew why.

But then you know what happens when one assumes! [img]/wwwthreads_images/icons/smile.gif[/img] It frequently happens to me.

LEVE is offline  
post #5 of (permalink) Old 12-12-2001, 05:30 PM
Join Date: May 2001
Posts: 3,501
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Removing Emissions?

You assumed? well you know what "Assumed" did?

Followed a dump-truck and assumed it was a wedding?

My mother always used to get me with that one, only it was Thought, not assumed.

Infernozx is offline  
post #6 of (permalink) Old 12-12-2001, 11:19 PM
Posts: n/a
Re: Removing Emissions?

These were awesome directions I got from a member of the Jeep list... But definitely have a haynes manual and Jeep service manual to guide you as well. I am running the BBD carb with no problems (knock on wood) at the moment so I would only swap it out if you are having trouble with it. I also modified my stock air cleaner because the baffle was not openeing correctly and limiting airflow. Now it is basically an open element after some work with a grinder and sawzall. I also cut the air tubes with a sawzall coming out of the ehaust and made up some caps to cover them off. My truck runs like a champ now. Make sure you check the timing though after you screw with the computer. I also have an HEI distributor waiting to go in...

(Here they are as I received them...)

I will try to paint a pic, of what I did, but since our vehicles are different years, some things may be different.
1. The line coming off the intake manifold under the carb. I left the larger hose on(going to the brake booster), and plugged the small port.
2. Removed the line coming off the carb base pointing to the radiator, and plugged it off.
3. Removed the line coming off the carb base pointing to the brake booster, and plugged it off.
4. Left the line on #6 intake manifold runner alone.
5. Removed the solenoids from the valve cover and firewall, and all the lines connected to them. (lots of lines) If lines went to the vaccum res. in the rt
fender I capped the ports on the res., that they came from.
6. Removed all related lines from vac. tree below and to the front of the carb.
7. Left pcv hose alone.
8. Left carbon canister alone.
9. Vac advance now comes off of port 1/2 way up carb facing valve cover. Put a T in this line, and run the egr off of this line also.
10. Follow the nutter bypass instructions, and add the mod that I did, if you want your carb to react with the O2 sensor. I like how it runs when the carb is doing what it is supposed to. It saves the catalyst also.

Just remember, because the vehicles are different years, you may end up with an extra line here or there leaking vac. Just plug it off. All vaccum leaks are bad. I also pretty much gutted my air cleaner, and removed the flapper in the snorkle. It had a bad diaphragm. It didn't effect how my critter ran to any noticable degree.

(this is a modification to the nutter bypass that worked well for me as well....)

You essentially leave the orange wire from the distributor alone, and take the wire that nutter wanted you to hook up to the orange wire from the distributor and piggyback it on to that wire also. The orange wire from the dist. to the emissions control unit will just have an extra wire tied into it, from the ignition control unit. Everything else is as Nutter instructed, except unplugging your carb.

Jon - 1985 CJ7, 258, 77k, T-176, Dana 300, 1" body lift, 31's, wrangler tub, yellow!
post #7 of (permalink) Old 12-13-2001, 06:33 PM
Posts: n/a
Re: Removing Emissions?

you do something like this for your own thing.
i came from mich to az, and i am TOTALLY screwed
because of the emissions thing. this jeep
had NOTHING on it anymore.
i have NO idea what to do.
and it's STUPID! at LEAST......can i buy your stuff?

when in doubt.........
empty the magazine.
post #8 of (permalink) Old 12-14-2001, 03:54 PM Thread Starter
Join Date: Oct 2001
Posts: 409
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Removing Emissions?

LEVE- you are right. I did not want to know why, it is becasue i do know why. Looking to make it run a lot better for the lowest buck.

The head of a 4.0 will fit perfectly? Witch set of rods do you use?

Thanks for the info. I will begin to plan my attack and look up "nutter bypass"

Headed for Gunnison, soon....

87Warrior is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome