Incomplete Emissions Inspection

[Hulk]

The #1 is the one the ECM uses to control air/fuel so it should be all over the map. The #2 is there to check catalytic converter is working.

Hmmm. So maybe my O2 sensors are working as designed.

 

[MountainGoat]

I'm no pro, but I am pretty sure a flatline signal from an O2 sensor means it is bad. That or the wiring is knackered.

 

[Hulk]

Here's what Fusion OBD is showing. The green is sensor 1 and the red is sensor 2.

 

[DaveInDenver]

The green #1/upstream looks like what you'd expect. An O2 should swing across 0.5V as you drive. You'll never stop swing over and under 0.5V, which represents the perfect air-fuel ratio. You're always going from lean to rich and back as you drive, which the ECM is constantly trying to adjust for. Using a OBD scanner like this is slower than the ECM is actually working, which you could see with an oscilloscope or voltmeter on the O2 itself. It's very active in a good O2.

The rear #2/downstream O2 should be less active than the front if the catalytic converter is working. But I'd expect it to be around 0.5V, not 0.9V. At least if you're not failing for excessive unburnt HC when you test at Air sCare.

So I'd suspect the #2 isn't working correctly. But I wouldn't necessarily say it's bad. These sensors are not absolute values, they're relative O2 measurement to the ambient atmosphere. You can have a good O2 that has it's outside air port blocked so it's not properly measuring relative to the actual air around it. Replacing it would probably fix it but it could that yours is just clogged and a cleaning would solve it.

 

[Hulk]

UPDATE: I replaced my ancient exhaust system with all-new OEM parts, including new catalytic converters and new Denso O2 sensors. It's shiny and quiet, but the catalyst test still didn't complete. So last night I drove the pattern that @satchel posted.

With initial intake air temperature above 50° F, the test looks like this:

• Drive 3 minutes at at 40-55 MPH
• Then drive 7 minutes at 35-45 MPH
• Drive with smooth throttle operation
• Avoid sudden acceleration
• Avoid sudden deceleration as much as possible with the throttle fully closed
• Engine temp must be 176° F or greater
• Also read somewhere that this should be done with about a half tank of gasoline

All the roads near me have never-ending stoplights, so I drove the pattern on I-25 at 9:00 pm so traffic was flowing freely. During the first 3 minutes, I drove just under 55 MPH which is hard to maintain when everyone is zipping past at 70 MPH. @Mrs Hulk sat in the passenger seat with the stopwatch app on her phone, and she kept warning me to slow down. During the second part of the pattern, I set my cruise control at 40 MPH, turned on my hazard lights, and drove in the right lane like I was limping home a barely-working vehicle.

It worked!!!

This morning, I went back to Air Care Colorado. I finally passed the OBD test but they failed me on the gas cap. Made the trip to NAPA, bought a gas cap for $12.50, drove back to Air Care Colorado, and finally passed.

I bet auto parts stores in Colorado sell 1000% more gas caps than in non-emissions states.

New exhaust parts:

Shiny exhaust under a rusty back bumper:

OBD Fusion with the good news that my Catalyst test finally completed:

 

[satchel]

Great news! For posterity sake, the times required to run for the various steps are minimums, so don't worry if you drove the 3 min step for 10 mins then proceeded to the next step. I usually run each step for a min or more than the minimum. I've never been able to do it all correctly the first time, so if all steps are ran and still not showing as ready, turn the truck off and wait a min, then start it up and try again.

 

[nuclearlemon]

UPDATE: I replaced my ancient exhaust system with all-new OEM parts, including new catalytic converters and new Denso O2 sensors

good lord, how much did that cost?!

 

[Hulk]

good lord, how much did that cost?!

>$3,000

 

[DaveInDenver]

>$3,000

I rationalize expensive stuff like this by remembering "At least my hobby isn't driving a vintage Porsche or sports betting."

 

[Hulk]

I rationalize expensive stuff like this by remembering "At least my hobby isn't driving a vintage Porsche or sports betting."

I've been patching my exhaust together with rando parts for the last 10 years. I figure this new exhaust will probably last the rest of my life, and I'm planning to live a good long while yet.

 

[AimCOTaco]

Nice job Matt, new stuff is nice, way to hang with it!

Don't forget to lick your gas cap seal before the smog test kids. (or smear some plumbers silicone grease on there if you're a smarty)

 

[Notyourmomslx450]

UPDATE: I replaced my ancient exhaust system with all-new OEM parts, including new catalytic converters and new Denso O2 sensors. It's shiny and quiet, but the catalyst test still didn't complete. So last night I drove the pattern that @satchel posted.

With initial intake air temperature above 50° F, the test looks like this:

• Drive 3 minutes at at 40-55 MPH
• Then drive 7 minutes at 35-45 MPH
• Drive with smooth throttle operation
• Avoid sudden acceleration
• Avoid sudden deceleration as much as possible with the throttle fully closed
• Engine temp must be 176° F or greater
• Also read somewhere that this should be done with about a half tank of gasoline

All the roads near me have never-ending stoplights, so I drove the pattern on I-25 at 9:00 pm so traffic was flowing freely. During the first 3 minutes, I drove just under 55 MPH which is hard to maintain when everyone is zipping past at 70 MPH. @Mrs Hulk sat in the passenger seat with the stopwatch app on her phone, and she kept warning me to slow down. During the second part of the pattern, I set my cruise control at 40 MPH, turned on my hazard lights, and drove in the right lane like I was limping home a barely-working vehicle.

It worked!!!

This morning, I went back to Air Care Colorado. I finally passed the OBD test but they failed me on the gas cap. Made the trip to NAPA, bought a gas cap for $12.50, drove back to Air Care Colorado, and finally passed.

I bet auto parts stores in Colorado sell 1000% more gas caps than in non-emissions states.

New exhaust parts:

Shiny exhaust under a rusty back bumper:

View attachment 119828

OBD Fusion with the good news that my Catalyst test finally completed:

View attachment 119827

Hey @Stuckinthe80s have you tried this for yours??

 

[Stuckinthe80s]

Hey @Stuckinthe80s have you tried this for yours??

Something similar, but not this exactly. But you can bet I'm going to!

 

[simps80]

great thread!

my 1997 fzj80 had an incomplete test yesterday
for catalyst not ready

i found the drive pattern documentation on mud not knowing this thread was here..

just recently fixed p0325 with the knock sensor harness fix after p0171 p0133 and p0130 which were fixed like Matt with all new toyota oem exhaust (ouch) including cats but bosch o2 sensor…

anyway took it in yesterday to find out about this get and catalyst not ready situation.

I followed drive pattern 2 and 3 and it finally went ready from not ready on the scan gauge…
yes it’s true you can’t tell which system the scan gauge is triggered for not ready but it does tell you it’s not ready…
after following the patters for both to the letter the scan gauge finally read “ready” from the main scan window so I took it back to CAC testing and it FAST PASSED

i have never seen such a thing, it was only on the wheels of death for like two minutes
i was so relieved!!
i was worried somehow something was still wrong with o2 sensors or something but no it just needed those patterns to map correctly

these levels are so insane