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View Full Version : Mallcrawling at its finest (emissions)



ATL ZJ
10-02-2004, 05:15 PM
:roll: Yes, my vehicle is registered in metro Atlanta so I have to pass emissions. You're right, this is a JU question, but everyone there talks out of his ass. That said...

I was fine until I chopped the exhaust and ran a turndown right after the muffler to clear the tri-link. Well, my NOx numbers aren't the best. Readings are:

25/25 test- 1407 NOx ppm. (930 Allowed)
50/15 test- 1550 NOx ppm. (1017 Allowed)

Should I throw a new cat on there? Or drive it a lot longer before I get it tested? :x

Pearce
10-02-2004, 05:39 PM
Shit boy, my 94 YJ is better than that! And the allowable was different. Strange for being the same 4.0 motor.
25/25 test - 30 NOx ppm allowable 1047
50/15 test - 48 Nox ppm allowable 1146

You sure u had the motor up to temp for the test? If you were asking drive it longer before you actualy test it that day, then yes I would. I think running a higher octane can help to, but not sure.
Maybe try one of those addatives to reduce it first.

Just thought of another thing, you sure you were not reading the RPM numbers right below the NOx number? Thats around the RPMs for the tests.

ATL ZJ
10-02-2004, 08:24 PM
Yeah I am pretty sure I was reading the right ones :D:. The temp showed about what it usually does, but I only drove it 3 minutes to the test location. I'll run down what gas I have in there now, toss in some 93 octane and additive, and test it again on Monday.

The tailpipe probe was basically in the muffler... And I had to use a strap wrench connected to the lower control arm to keep it from falling out of the turndown. :lol:

When did you get yours tested Pearce? The only thing I can think of is maybe that the allowable values have gotten stricter recently.

robselina
10-02-2004, 09:21 PM
what about doing the Mopar CCC treatment mentioned in the FAQ section? If you can clean out the chamers and the valves a little, might be enough to do the trick...some injector cleaner won't hurt either...

talking out my ass but hopefully it's not too bad advice :lol: We don't have emissions testing out here, actually, I just gutted the emissions system in my car, it's amazing how much better it runs :roll:

ATL ZJ
10-03-2004, 02:09 AM
We don't have emissions testing out here, actually, I just gutted the emissions system in my car, it's amazing how much better it runs :roll:

No shit, power and enviromental "friendliness" are opposites. I might try the CCC business if nothing else works.

Other ideas still welcome...

LouisianaZJ
10-03-2004, 02:43 AM
how bout cleaning the airfilter (replacing) and cleaning the TB

Pearce
10-03-2004, 06:12 PM
My test was earlier this year so they may have gotten harder to pass. But My YJ has been on its top once, and that was with the stock cat. So ya gotta figure some crap was in there. Shouldnt matter that you have a turn down. But you do need to run it longer than 3 min. Since your having a problem I would say go ahead and run it on 285 for a bit first. If you have to dyno it, the place by my house has a guy thats real cool about testing big Jeeps. Maybe change out your O2 sensor if you haven't recently. I did that too before my test, also had the high octane in it.

bambamzj
10-06-2004, 10:17 PM
Throw some grain alcohol in half a tank of gas and run at highway speeds for 20 minutes before testing. Hillbilly Engineering at its finest but it works.

ATL ZJ
10-07-2004, 04:19 PM
Well, I failed a second time :?. Cleaned my whole intake out, ran some of that fuel injector cleaner/ guaranteed to pass stuff/ and drove around 20 miles beforehand. I was finishing breaking in my front gears at the same time so I didn't get up to really high speeds though. The NOx numbers were still high but went down a little bit. I'm thinking maybe a new cat or at least an O2 sensor is in order.

Pearce
10-07-2004, 04:38 PM
Found this for future info:

Some Reasons Why Your Vehicle Might Fail the OBDII Test (1996 and newer)

The OBDII system test determines whether there is a malfunction or deterioration of up to 175 emission-control devices. The systems monitored by OBDII include:

Catalytic converter
Fuel delivery
Secondary air
Misfire
Evaporative emissions control
Oxygen sensor
Exhaust gas recirculation (EGR)
Continuous monitoring of the power control module


Some Reasons Why Your Vehicle Might Fail the ASM Emissions Test (1995 and earlier)

Excessive Hydrocarbons (HC)

These emissions result from unburned fuel. Check for problems with the following:

Internal engine trouble
Faulty air pump
Ignition system
Exhaust gas recirculation system (EGR)
Catalytic converter
Gas cap


Excessive Carbon Monoxide (CO)

High amounts of carbon monoxide occur in a rich fuel mixture when there is too much or too little air reaching the combustion chamber. Check for problems with the following:

Mis-adjusted carburetor
Faulty fuel-injection system
Dirty air filter
Worn rings or valve guides
Air pump system

Oxides of Nitrogen (NOx):

High levels of NOx can be caused by excessive temperature in the combustion chamber or a damaged catalytic converter. Check for problems with the following:

Air injection system
EGR system
Combustion chamber deposits

ATL ZJ
10-07-2004, 05:49 PM
That's similar to the list they have at the test centers. At least for the pre-96 NOx section, with about 4 more items, including cat and 02 sensors. There's a decent chance that I have deposits on the cylinder walls after about 150k miles, but I suspect something in addition to that is preventing me from passing. I'm leaning towards it being the cat at this point since my ZJ has killed them every 3-5 years for its whole life. And the one on there is 3 years old and was recently beat around a little bit during some exhaust work to clear the tri-link under there.

FinlayZJ
10-08-2004, 09:34 AM
I called my friend at Goodyear and he thinks it sounds like the cat w/o being able to see it tested in person. If you're borderline failing in other areas, a hi-flow cat wont be any help. Just get a regular OEM or similar cat. Or just change residency to SC. I don't believe they have emissions testing. It might be cheaper if you have to chase 100 million emissions items.

ATL ZJ
10-08-2004, 04:54 PM
Changing my residency to SC would be pretty difficult since I live on-campus rather than in a house with a real address. I'm pretty sure that it's considered only temporary residency by the college.

That advice leads me to suspect the cat even more, so I might grab a new one and see. I have some other exhaust work in need of doing since the turndown is melting one of the bushings on the trilink.

FinlayZJ
10-11-2004, 08:03 AM
Changing my residency to SC would be pretty difficult since I live on-campus rather than in a house with a real address.....

Sorry, it was a failed attempt at a joke.

Replacing all the emissions equipment if it's not the cat will get real expensive real quick. => Moving to SC is cheaper.

All humor is now lost. Carry on..........

ATL ZJ
10-11-2004, 02:49 PM
Changing my residency to SC would be pretty difficult since I live on-campus rather than in a house with a real address.....

Sorry, it was a failed attempt at a joke.

Replacing all the emissions equipment if it's not the cat will get real expensive real quick. => Moving to SC is cheaper.

All humor is now lost. Carry on..........

Haha sorry. I seriously considered selling the vehicle to a very close friend who lives in SC and being done with this, so it didn't seem that far-fetched. I figured it wasn't the best idea though... :lol:

Bulldog 6
11-17-2004, 10:29 AM
So what is the latest to this story? Did ya get it to pass? What did you have to change out?

ATL ZJ
11-17-2004, 02:40 PM
I filed for an emissions waiver since myself and the Jeep are out of state at school. It was granted, but only until 1/1/05. So I will be solving this fiasco over Christmas break. I'm going swap in a new cat.

Any sources for cheap cats? I don't really need a high-flow cat because my exhaust is already pretty loud with the FM 40 and turndown right the muffler.

FinlayZJ
11-19-2004, 04:56 PM
Ghetto G & S muffler on Canton Highway did mine for about $120 installed.

ATL ZJ
11-19-2004, 05:58 PM
Ghetto G & S muffler on Canton Highway did mine for about $120 installed.

Ooh I like the sound of 120.

ATL ZJ
12-19-2004, 11:20 PM
Which one? I didn't find a Canton Highway location, but there's on in Marietta on Lower Roswell, one in Kennesaw on Cobb Pkwy NW, and one in Woodstock on Main St.

ATL ZJ
12-22-2004, 07:02 PM
Got the new cat in. Passed emissions today.

Old readings:

25/25 test- 1407 NOx ppm. (930 Allowed)
50/15 test- 1550 NOx ppm. (1017 Allowed)

New readings:

25/25 test- 268 NOx ppm. (930 Allowed)
50/15 test- 158 NOx ppm. (1017 Allowed)

nate
12-24-2004, 08:16 PM
:shock: New cat made a HUGE difference!