Failed Colorado Emissions

**LaddieHanus** · 03-31-2011, 02:45 PM

97 TJ 4.0 Automatic 130,000 miles

Took it in to the test station last week after changing the oil and air filter.

HC 1.306 Limit 1.200
CO 18.8110 Limit 15.000
NOx 6.6770 Limit 3.000

Replaced the spark plugs and the O2 sensor on the ex manifold and took it
in today

HC 1.3029
CO 18.4293
NOx 6.2924

In the last 2 years since it passed I have rebuilt the transmission and replaced the radiatior. Before this it sat a lot because the tranny was in bad shape.

The High NOx numbers have me confused otherwise I would just replace the catalytic Converter. The entire exhaust including the converter was replaced about 9 years ago when the mainifold cracked in a number of places and I put on a Borla header and catback.

Anybody got any ideas? I was planning on a V8 swap this summer but it would be nice to have this running till then.

Laddie Hanus

bluefox_gt · 03-31-2011, 05:14 PM

Alot of the time aftermarket coverters stop doing there job faster than OEMs. The NOX is pretty high. Try checking the PCV valve or check the header and exhaust for air leaks. Run some seafoam or injector cleaner through it. When have your T-stat been changed?

SilverTJMike · 03-31-2011, 05:52 PM

Was it good and hot, usually helps, and not drive down the road hot but drive down I-25 hot? One of my cars failed, the mechanic took it back and it passed, he just warned it up.

dm0ney · 03-31-2011, 05:59 PM

My wife's 4Runner failed due to high NOx (4.5573) and it turned out to be the catalytic converter. (Well I assume that, since we replaced the new catalytic converter and then it passed.) The shop we took it to said the majority of the time they see high NOx it is the catalytic converter.

However her HC and CO readings were both well under 1.0, unlike your readings, so maybe you've got something else going on. Not to mention possible differences between a 4Runner and a Jeep. But I figured I'd mention it anyway.

**freeskier93** · 03-31-2011, 06:07 PM

I bet its your cat. I went through this same thing exactly. Replaced o2 sensors, spark plugs, oil, etc...

Pulled out my emissions reports, I kept failing at:

20.9 PPM CO2
1.23 HC

Brought it to a mechanic who hooked it up to their computers, they said the o2 sensors were reading the same thing, indicating the cat was bad. Replaced the cat and dropped down to 5.6 PPM CO2 and .5 HC. NOX also dropped down a bit. I wish emissions would tell you this kind of thing instead of "you failed, figure it out yourself", when they could easily have told me this since they hook up to the computer.

Your higher NOX is a bit odd, maybe try changing the oil and check the CCV components. I bet it's your cat.

**LaddieHanus** · 03-31-2011, 07:10 PM

Its a hour drive from Nederland to the emissions station in Broomfield so I am pretty sure it was hot enough. The tstat was replaced with the radiator last year and the temp gauge shows no overheating. Leaning to Seafoam and replacing the Cat.

Aftermarket cats dont seem to have a good reputation. Wonder if I have the original around.

**Knuckelhead** · 03-31-2011, 07:11 PM

Quote:

Originally Posted by bluefox_gt

Try checking the PCV valve

TJ's don't have a PCV. They do have a CCV and it's not a valve...

bluefox_gt · 03-31-2011, 07:17 PM

Quote:

Originally Posted by Knuckelhead

TJ's don't have a PCV. They do have a CCV and it's not a valve...

I thought pre 99 or 2000 had them, I didnt know I know mine doesnt

AFD113 · 03-31-2011, 08:33 PM

have you tried this? http://www.amsoil.com/storefront/api.aspx Have had good results. $ back guarantee too!

**freeskier93** · 03-31-2011, 09:37 PM

Quote:

Originally Posted by LaddieHanus

Its a hour drive from Nederland to the emissions station in Broomfield so I am pretty sure it was hot enough. The tstat was replaced with the radiator last year and the temp gauge shows no overheating. Leaning to Seafoam and replacing the Cat.

Aftermarket cats dont seem to have a good reputation. Wonder if I have the original around.

lol, why do you go to broomfield? There's a testing facility right here in longmont, 45 minute drive from ned.

**freeskier93** · 03-31-2011, 09:39 PM

Quote:

Originally Posted by bluefox_gt

I thought pre 99 or 2000 had them, I didnt know I know mine doesnt

Nope, there just two little plastic elbows coming from the valve cover. One goes to the manifold and the other to the intake tube.

2005X · 03-31-2011, 09:41 PM

Quote:

Originally Posted by freeskier93

lol, why do you go to broomfield? There's a testing facility right here in longmont, 45 minute drive from ned.

or go to the one in Boulder. thats where i went and passed

**freeskier93** · 03-31-2011, 09:46 PM

Quote:

Originally Posted by 2005X

or go to the one in Boulder. thats where i went and passed

Ha, I wasn't sure if their was one in boulder. That makes it a 30 min drive.

SilverTJMike · 03-31-2011, 10:40 PM

Boulder one is just past the airport and the jail, end of the road on the left.

**LaddieHanus** · 04-01-2011, 12:41 PM

I work over in Broomfield so its the closest. I actually live off of Magnolia road so its quicker to take Coal Creek Canyon. Lived in Longmont until about 15 years ago (bought the YJ over at Herbert Motors new in 89) so I have used all 3 stations since Envirotest came in the 90's. Will probably go to Boulder for the retest as Broomfield guys moved me to a different lane yesterday and the 2 cars behind me left before I did. I also try to avold driving in Boulder whenever possible.

Anyone know of anyplace local that has the Seafoam spray. I have a couple of bottles that I bought at NAPA but have not found the spray at Napa or autozone.