Emissions Help

[lunchbox3]

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:

 

[RMETeeJay]

That stinks, BTDT. In case you weren't aware, they set a limit on your expenses to pass so keep all of your receipts.

Do you currently have any OBDII codes? Did you replace the O2 sensors with the recommended brand (NTK)? How is your MPG and does it smell like it runs rich?

 

[Jerry Bransford]

How's your engine temperature at the time of the test? It needs to be as hot as possible to pass. Is the correct 195 degree thermostat installed? A lower temperature thermostat can cause an engine not to pass its smog test.

 

[lunchbox3]

That stinks, BTDT. In case you weren't aware, they set a limit on your expenses to pass so keep all of your receipts.

Do you currently have any OBDII codes? Did you replace the O2 sensors with the recommended brand (NTK)? How is your MPG and does it smell like it runs rich?

No OBDII Codes. O2 Sensors were the recommended brand listed in our O2 Sensor master thread. MPG seems fine, my buddy thought it smelled like it was running rich a month or two ago but I can't really tell.

How's your engine temperature at the time of the test? It needs to be as hot as possible to pass. Is the correct 195 degree thermostat installed? A lower temperature thermostat can cause an engine not to pass its smog test.

Engine temp seemed fine - after I got off the highway and was sitting in line for the test the needle was just sitting at 195 (or what I assume to be 195). I replaced the thermostat a couple years back and used the forum here to order my (stant?) thermostat.

 

[RMETeeJay]

If the gauge is sitting at 195 fully warmed up, you're most likely running too rich. Exhaust will smell a little like gas and tailpipe will have black soot inside.

Use an OBDII reader that shows the reported engine coolant temperature (ECT) so you can figure out what coolant temps you're running at when fully warmed up.

 

[tworley]

HC and CO being that high I'd take a look at the cat. Is it original?

 

[freeskier93]

It's time to replace your cat.

 

[Jerry Bransford]

No OBDII Codes. O2 Sensors were the recommended brand listed in our O2 Sensor master thread. MPG seems fine, my buddy thought it smelled like it was running rich a month or two ago but I can't really tell.



Engine temp seemed fine - after I got off the highway and was sitting in line for the test the needle was just sitting at 195 (or what I assume to be 195). I replaced the thermostat a couple years back and used the forum here to order my (stant?) thermostat.

The temperature gauge is supposed to be at 210 or close, not 195. That's a clear sign the thermostat is defective or a lower/incorrect temperature thermostat was installed like a 180. Replace it with the correct 195 degree (non-failsafe!) thermostat so the engine will start running at the correct 210 degrees. It may pass the smog check then since an engine that isn't fully warmed up won't pass.

 

[IJK]

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

This thread may help, https://wranglertjforum.com/threads/failed-emissions-help-the-fng-please.35582/ , , keep us posted on your progress and the solution. Thanks

 

[lunchbox3]

The temperature gauge is supposed to be at 210 or close, not 195. That's a clear sign the thermostat is defective or a lower/incorrect temperature thermostat was installed like a 180. Replace it with the correct 195 degree (non-failsafe!) thermostat so the engine will start running at the correct 210 degrees. It may pass the smog check then since an engine that isn't fully warmed up won't pass.

Well shoot! Alright I'll give that a shot. Thanks, Jerry. I'll keep everyone updated in case the thread helps someone else.

 

[freeskier93]

The temperature gauge is supposed to be at 210 or close, not 195. That's a clear sign the thermostat is defective or a lower/incorrect temperature thermostat was installed like a 180. Replace it with the correct 195 degree (non-failsafe!) thermostat so the engine will start running at the correct 210 degrees. It may pass the smog check then since an engine that isn't fully warmed up won't pass.

Exact temperature the engine runs at is going to vary. During the winter my 4.0 has always run between 190 and 200, with an external reader you could pretty easily pinpoint when the thermostat was opening and closing. During the summer it runs closer to 200 to 205, rarely ever actually see it hit 210. Usually only see it hit 210 when it's exceptionally hot and off roading.

I can assure you I've never run anything other than a regular 195 Stant thermostat.

 

[freeskier93]

Well shoot! Alright I'll give that a shot. Thanks, Jerry. I'll keep everyone updated in case the thread helps someone else.

You can either keep chasing your tail or bite the bullet and replace the cat. The fact that Nox, CO, and HC are all failing (but not by a ton) pretty squarely points to the cat going bad. If just one was failing or extremely high that would point to something else, but those numbers are typical of the cat going bad, they should all be about half what they are.

Engine temp of 195 vs 210 isn't going to make that big a difference as long as the PCM is in closed loop (which it is at those temperatures).

 

[Jerry Bransford]

Exact temperature the engine runs at is going to vary. During the winter my 4.0 has always run between 190 and 200, with an external reader you could pretty easily pinpoint when the thermostat was opening and closing. During the summer it runs closer to 200 to 205, rarely ever actually see it hit 210. Usually only see it hit 210 when it's exceptionally hot and off roading.

I can assure you I've never run anything other than a regular 195 Stant thermostat.

Except in extreme cold I've never see a 4.0 run at those temps with a 195 degree thermostat that was functioning properly. 210 or close is what it most commonly runs at in non-cold conditions.

 

[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

I would check the cat. Get and IR thermometer and check inlet vs outlet temp of the cat. Outlet should be at lead 200 degrees hotter. Then check it after holding the RPM at about 1500 for 2 to 3 minutes. If it is. Enter after holding the idle, I would do that right before they pull it in for the test.

 

[ColoJeep]

For E - tests I always drive the last 2-3 miles in 2nd or 3rd gear to get the exhaust temp up (cats) .
Basically work the engine , to get the cat temp up where it works better.
However , seeing the weird spikes from the OP's E test I doubt this would help much. Sorry man.

 

[freeskier93]

FYI, Colorado started doing "2nd chance" runs, during the same test, a number of years ago. My assumption is they started doing this because a lot of people were failing due to cold cats; whether from sitting in line or not driving enough prior to getting there.

Unless there is no line, and I can drive right in, I rarely pass on the initial run. You can watch their monitor and it will show all this.

Long story short, it's unlikely you are failing due to the cat not having enough time to warm up.

 

[freeskier93]

Another thing to point out, the PCM switches to open loop under moderate to hard acceleration. You can see in your printout at 160 seconds the throttle position is 78%. During that harder acceleration the PCM is most definitely switching to open loop, which is going to cause emissions to go way up.

 

[Pantera99]

Hmmm, all they do in AZ anymore is make sure your check engine light isn't on, unless it's pre-1996.

 

[ColoJeep]

Hmmm, all they do in AZ anymore is make sure your check engine light isn't on, unless it's pre-1996.

Here , Jared want's us to desperately to be Kali.

 

[IOwnCalculus]

Can't blame CA, they don't sniff OBD2 vehicles either.