Jeep Emissions Testing

[steveh_131]

I'm just about out of ideas with this, but hoping someone here can give me some insight.

I've got a 1997 Jeep Grand Cherokee Laredo, with the 4.0L inline 6. I've seriously rebuilt this thing from the ground up. Spent a lot of time and money on it. Unfortunately that has involved a lot of battery disconnects over the last year or two - and now it won't pass the emissions test.

I've got an OBDII bluetooth adapter and the Torque app on my phone. The last remaining test is the Catalyst - and it has been at a constant 'Catalyst Not Ready' state for ever now. I've done so many drive cycles, put hundreds of miles on it, and now both 30-day temporary tags have expired and it still won't pass the test.

The catalytic converter is definitely marginal at best - but it doesn't throw a code. It just says it's 'not ready'. It has a new-ish aftermarket O2 sensor. O2 heater test passes, everything else says 'ready' but the catalyst.

Does anyone here know any tricks for this model of Chrysler to get it through that damn drive cycle? I've read a few folks say that a marginal catalytic converter sometimes keeps it from throwing the ready flag, so I'm going to go ahead and replace that. But once I do, I might be able to get another 30 day temp tag to drive it and try to get it to pass.

Any info would be greatly appreciated. I won't even get started on the tyranny of emissions testing, except to say that someone should be tarred and feathered.

 

[HoughMade]

...I won't even get started on the tyranny of emissions testing, except to say that someone should be tarred and feathered.

I will. It simply makes all the sense in the world that only a very counties have emission testing (not that I'm wishing it on anyone). I mean CLEARLY any air pollution there may be in NWI is due to individual passenger vehicles, right? What else could it possibly be?

...and as for your issue, yes, I've heard the same thing about a marginal cat. Being a '97 and that particular engine, while great for its intended purpose, is not inherent a clean runner, so the cat has been working very hard for 17 years.

 

[steveh_131]

I will. It simply makes all the sense in the world that only a very counties have emission testing (not that I'm wishing it on anyone). I mean CLEARLY any air pollution there may be in NWI is due to individual passenger vehicles, right? What else could it possibly be?

I literally can not think of a single factor causing air pollution in northwest Indiana other than my fully maintained Jeep Grand Cherokee with its missing readiness flag, spewing carbon monoxide into the atmosphere and causing a hole in the sky.

 

[steveh_131]

...and as for your issue, yes, I've heard the same thing about a marginal cat. Being a '97 and that particular engine, while great for its intended purpose, is not inherent a clean runner, so the cat has been working very hard for 17 years.

This was my thought as well, so I actually did a quick trick by installing these spark plug non-fouler devices to pull the O2 sensor out of the air stream as a test. Supposedly this will pass the test even with no catalytic converter whatsoever, so I thought it would at least tell me if my cat was bad. It's a no-go. It's still my best guess so I'll go ahead and replace it.

I still need the damn drive cycles for this model. I swear, if you look it up you will find 10 different versions, all of them completely different. I may have to do this on expired tags so I don't have 6 hours to run around drawing attention to myself with all these ridiculous drive cycles.

 

[Clay]

you should have a pre-cat and post-cat O2 sensor.

If the post-cat O2 sensor isn't seeing a difference from the pre-cat sensor, then you're going to have an issue. Whether that will hold you out of closed loop operation I'm not sure, but I know it will cause issues and usually throw an emissions code. If you're going to replace the cat, then I would get that done and I bet that helps or fixes your issue.

On that note if you're going to replace the cat, KEEP THE OLD ONE! take it to a scrap yard, with proof that it was replaced (receipt, etc), and you can sell them. Some can be worth a pretty good chunk of change.

 

[steveh_131]

Never occurred to me to scrap the old one. Will a receipt for the new part be sufficient, or do they require a receipt for its installation as well?

Thanks for the idea!

 

[rosejm]

I had a similar experience, and found that you may need to find the exact specs for your ECM's catalyst ready test.

They can be for a very limited range of sensor values as I found for my Neon.
It required a 37-48 MPH, 1300-1700 RPM rage to execute the test. As I never lugged the engine around town in 5th gear, I wasn't matching the ranges the ECM was looking for and never activated the test.

Took one drive out of town and loafed it less than a mile. Everything was ready after that.

 

[steveh_131]

Ok, that must be what I'm missing. I just can't find those exact specs anywhere. Any Chrysler experts around here know what it is for this model, or where to find it?

On another note, a $150 Walker catalytic converter from advance auto parts, minus $50 coupon code TRT30, minus a $50 rebate from Walker.... it looks like I may break even on this thing once I scrap my old one.

 

[Clay]

Not sure on the receipt. I know the last one I tried to scrap they wanted either the title for the vehicle or proof that it had been replaced.

 

[steveh_131]

Ok. Do you think I should replace the O2 sensor with an OEM replacement? I think I put a bosch in there. It's not throwing any codes, but could it be preventing the catalyst test from completing even without throwing a code?

 

[Clay]

I wouldn't worry about it. I've not had any major issues with bosch sensors. If your worried put a volt meter on it and watch the output.

 

[Mr. Habib]

Does it show any codes?

Reading comprehension failure, my bad.

 

[Mr. Habib]

Can you monitor the O2 sensors?

 

[steveh_131]

Can you monitor the O2 sensors?

No codes yet. I can monitor the sensors if I knew what to look for.

I've been investigating the Mode 6 data through my android app. I'm seeing some interesting failures, but I can't figure out how they're related. Note that these aren't normal codes that trigger check-engine lights. They are hidden codes.

According to those codes, the following tests failed:


----
TID:$13 CID:$01
-
Max: 16
Test result value: 114
FAIL
----
TID:$15 CID:$01
-
Test incomplete or dependant test failed
--
TID:$19 CID:$01
-
Min: 3,760
Test result value: 1,581
FAIL
----
TID:$1a CID:$01
-
Min: 15,722
Test result value: 2,440
FAIL
----
TID:$1c CID:$01
-
Min: 15,722
Test result value: 2,440
FAIL
----
TID:$35 CID:$01
-
Max: 16
Test result value: 128
FAIL
----

I found this explanation of each test:

So this tells me that I have problems with:

• O2 Sensor 1/1 Big-Slope Counter
• Catalyst Slow O2 1/1 Response Counter - Incomplete because dependent test failed?
• O2 Heater 1/1 Hot Trend Counter
• O2 Heater 1/2 Hot Trend Counter
• O2 Heater 1/2 Delta Voltage
• Catalyst Slow O2 2/1 Response Counter

So now.... I just have to interpret what these secretive codes mean.

 

[steveh_131]

Update: Hooked it up to the Torque app and went for a long drive while monitoring the RPM, air intake temp, coolant temp, etc. Finally made it 'ready'. Required a good long drive at 50mph then coasting down to 20 without touching the brake - fun times.

Thank you guys for the advice and help. I guess this one just took a long time. I cleaned the ground connections a while back, I'm wondering if I fixed the issues then and it just needed more drive time to finish the test.

 

[RyanGSams]

I just took my car to get tested yesterday. All monitors came back ready besides catalyst. So I just bought a Bluetooth obd2 device and going to see what it says.

Glad you got it figured out I'm hoping to get mine ready so I can retest Friday.