Emissions Help

[ColoJeep]

Wow , That's cool , now we suck worse that Kali in at least one area !
I guess it's a " follow the money " scenario now.

 

[freeskier93]

Wow , That's cool , now we suck worse that Kali in at least one area !
I guess it's a " follow the money " scenario now.

Denver metro area has a massive ozone pollution issue. IIRC we have to do emissions testing because we violate EPA ozone limits (we are in a non-attainment zone).

https://cdphe.colorado.gov/history-of-ozone-in-colorado
We have some of the worst air quality in the country.

 

[ColoJeep]

Denver metro area has a massive ozone pollution issue. IIRC we have to do emissions testing because we violate EPA ozone limits (we are in a non-attainment zone).

https://cdphe.colorado.gov/history-of-ozone-in-colorado
We have some of the worst air quality in the country.

That's unfortunately what happens when you build the metro area in a river bottom surrounded by higher ground and plaqued with temperature inversions.

 

[NskLJ]

I'm hoping to get some ideas for what is wrong before I have to take my 97 2.5L in to a mechanic. Been trying to pass emissions since June. Here's what I've replaced: both 02 sensors, CCV valve, evap canister and evap purge solenoid. I put some of the gumout in and ran through a tank of gas, then changed the oil and filter. Checked the plugs, they looked fine - plugs, wires, distributor cap and rotor were all replaced 3 years (about 15k miles) ago.

Second test, after the EVAP fixes, my CO was well within levels. This morning, I'm back up to over. No idea what's been going on.

Just took my third test - before going in I drove on the highway for 40 minutes and had inflated my tires to 35 PSI. Still failing. I have the readouts - it looks like at times the emissions levels are fine, but then they spike a bunch. Could this be a bad MAP sensor? Maybe someone here can give me some ideas.

Here's the data:
View attachment 358093


View attachment 358096

Have you checked the egr system also to verify it’s working?

 

[lunchbox3]

Have you checked the egr system also to verify it’s working?

No, hadn't considered it. I'll see if there's a youtube on how to do that. Thanks for the idea, it's been added to the list!

 

[Jerry Bransford]

I'd start with the replacement 195 degree thermostat.

 

[freeskier93]

No, hadn't considered it. I'll see if there's a youtube on how to do that. Thanks for the idea, it's been added to the list!

There is no EGR on a 97 2.5L.

 

[NskLJ]

There is no EGR on a 97 2.5L.

I was wondering about that, how are are they controlling the Nox emissions. Just strictly through the cat?

 

[freeskier93]

I was wondering about that, how are are they controlling the Nox emissions. Just strictly through the cat?

Yep, strictly with the 3-way cat.

The big red arrow pointing at the cat can't get much bigger. Modern 3-way cats control hydrocarbons (HC), Carbon Monoxide (CO), and nitrous oxide (NOx). If you're failing all 3, you can pretty damn well rest assured the problem is the cat.

 

[NskLJ]

Yep, strictly with the 3-way cat.

The big red arrow pointing at the cat can't get much bigger. Modern 3-way cats control hydrocarbons (HC), Carbon Monoxide (CO), and nitrous oxide (NOx). If you're failing all 3, you can pretty damn well rest assured the problem is the cat.

I am a Ford guy, this is my first Jeep so I wasn’t sure about the 4 cyl motor. I am sure cat also easy enough to test.

 

[freeskier93]

I am a Ford guy, this is my first Jeep so I wasn’t sure about the 4 cyl motor. I am sure cat also easy enough to test.

The 2.4L 4 cylinder might have it because it's a much more modern design, but the old 2.5L doesn't.

The later model TJs did add the mini cats on the exhaust header, but 97 the only emission devices are the single 3-way cat and evap system.

 

[NskLJ]

The 2.4L 4 cylinder might have it because it's a much more modern design, but the old 2.5L doesn't.

The later model TJs did add the mini cats on the exhaust header, but 97 the only emission devices are the single 3-way cat and evap system.

My Jeep is an 06 LJ, I have replaced all 3 cats on it. I have been out of the automotive business for about 18 years now.

 

[lunchbox3]

In case this helps anyone else: it was the cat. Replaced the thermostat and failed, almost identical numbers. Took it in to a shop finally and the mechanic told me he thought it was most likely the cat. So, with that replaced, I went and passed emissions. So if you're in CO and failing on all three, it may be time for a new cat.

Thanks to everyone for the suggestions. These new required California compliant cats aren't cheap.