OBDII Emissions - Catalyst Monitor Not Ready (2 Viewers)

[Heckraiser]

Hi Folks,

So I took my LX in for Colorado emissions a couple weeks ago. To my surprise, they did not put it on the rollers (I assume they must have decided 315's are too big?). When this is the case, they just check your ecu for "readiness"- basically if the ecu is communicating through the OBD2 port and not throwing any codes, you're good to go, no sniffer required.

I thought this would be an awesome bonus, but it's turning out to be a headache instead. My ECU is showing the catalyst as "not ready." I have read about the drive cycles to reset this, but find them completely impossible to achieve in the real world (start from cold, idle for ten minutes, drive at a constant 50mph for a half hour, idle for thee minutes, drive at a constant 30mph for ten minutes, etc... ) I can only imagine someone with a private race track or in a remote area would be able to achieve this. After several attempts, I haven't been able to replicate that procedure. The emissions guy also suggested just driving around gingerly for a few days--don't gun it. That hasn't worked either.

Are there any tricks to reset this?

 

[RoaringFork]

Have you cleared the ecm fault memory recently? Whenever the DTC memory is cleared the readiness monitors are reset.

Usually just driving around will set all the monitors. And sometimes they won’t set with your best attempt at the readiness drive.

Maybe if your catalyst is not as effective as it was, or it should be, it may take longer to set??

It looks like you can monitor the readiness. For now keep driving it and see if it switches to ready...

 

[mingles]

I just went through this in NJ. I could get all my monitors to set except the CAT. In the end it took 650 miles of driving over a week and a half to get the CAT monitor to go ready.

The other thing I did, at my long time mechanic's suggestion, was run two bottles of "CRC Guaranteed To Pass" fuel additive through the system. Maybe it was snake oil, but the monitor did set and it was a whole lot cheaper than digging into cats and O2 sensors.

Also, keep in mind that every time you clear the ECU, ALL the monitors reset. I was having EGR issues as well so once the EGR went READY, I didn't want to take the chance that it wouldn't go READY again by resetting the ECU to chase the CAT readiness.

 

[Rwhat]

Had the problem on my Tacoma. Was a bad downstream/post cat O2 sensor.

 

[Bambusiero]

Have just been going through this kind of OBD2 DTC readiness business on another Toyota/Lexus vehicle.
Yup - really difficult to drive at certain speeds for given times.

Be aware or this - it can block your DTC progress:
Any existing or pending MIL code will halt the readiness drive cycle.
You must be completely free of error conditions to make DTC progress.

Suggest finding a drive route and time of day that has minimum traffic to get in your way.
Like - 10PM.
However, the stated drive cycle times are more of a driver guideline than a strict exact requirement.
The ECU is following an internal algorithm and adding time up in some cumulative fashion.
Impossible to really know when it's counting or not.

Get an OBD2 reader than shows you DTC status on the fly, like like "Torque" or "Torque-Lite" that you show above - good.

You might find this document helpful (attached):
Lexus Technical Service Information Bulletin - READINESS MONITOR DRIVE PATTERNS, All '96 - '02.

p.s. Suggest going for a drive, watching the O2 Sensor #1 and #2 waveforms (on Torque-Lite).
#1 (upstream) should be banging up and down, 0 - 0.7V or so, in roughly a square wave - normal.
#2 (downstream) should be spending at least some time in the middle, 0.4-0.6 or so.
Doesn't seem to require staying in the middle full time for counting as a functional catalyst.
But - if it's just banging up and down, just like the upstream, then your catalyst isn't a catalyst, it's just a pipe.
> Replace, or do the citric / oxalic acid de-scaling restoration procedure.
> Worked for me on a 20 year old / 230K mile car. Could see the waveform difference before/after.

 

[bigredmachine]

when you perform the driving pattern the times should be cumulative and not continuous so no worries if you have to go below the speed or stop.

heres the monitor for cat readiness

 

[Rivman1243]

Usually if mine won't set the the cat readiness monitor its because the egr sys is about to throw the P0401 code. So when that happens I blow out the vacuum modulator. My egr actuator was disconnected when I bought it and consequently puts out lots of rust particles. I have since installed an inline filter to keep the vacuum modulator clean and its been working for about a year but this morning I did get a pending P0401 this morning

 

[Heckraiser]

Thanks for the suggestions guys. Both my cats are fairly new, so I doubt the problem is with the hardware, although I suppose it's possible my rear o2 could be having trouble. I'll just put some more miles on it and keep my fingers crossed. My registration technically expired sunday, but I have a 30 day grace period to get it to pass before I get into any real trouble.

 

[Bambusiero]

@Heckraiser - just take a look at your O2 sensor waveforms.
No fingercrossing needed - it will be very obvious if they are functioning and reacting to the constantly varying exhaust chemistry.
20 minutes driving around while comparing the #1 and #2 waveforms, you'll see.
DTC readiness and pending error codes won't keep you from looking at the waveforms any time you want to.
Indeed, a bad O2 sensor is your best case scenario - $70 or so and a few minutes wrenching and you're good again.

 

[Heckraiser]

Is "o2 sensor1 equivalence ratio" the correct display?

Or do I open up both "o2 volts bank 1 sensor 1" and "o2 volts bank 1 sensor 2"?

:edit: nevermind, I think I got it figured out (second option). Just need to find the time to drive and watch. Thanks again!

 

[Rivman1243]

Is "o2 sensor1 equivalence ratio" the correct display?

Or do I open up both "o2 volts bank 1 sensor 1" and "o2 volts bank 1 sensor 2"?

:edit: nevermind, I think I got it figured out (second option). Just need to find the time to drive and watch. Thanks again!

Here's a screen shot of the sensors and gauges I watch when I'm connected.

 

[Bambusiero]

Right, think you got it.

O2 1x1 V graph = Bank1 Sensor 1 (upstream, closest to engine) always actively banging rich, lean, rich, lean.
O2 1x2 V graph = Bank1 Sensor2 (downstream, farthest from engine) should be more of an average stochiometric value.

Bank2 has no meaning for the Landcruiser because Bank1 and Bank2 are Y-piped together before O2 sensors and cats.
I have a GS300 with a separate cat for Bank1 (cyl. 1,2,3) and Bank2 (cyl. 4,5,6) and so it has 4 O2 sensors.

Your O2 1x1 V graph looks fine, I think. The full scale swing proves the sensor is working, regardless of anything else.
Your O2 1x2 V graph (if truly representative) looks to be attenuated and sort of stuck near "lean".
Looks like it's trying to work, but can't quite, like it's coated (guessing here).
If that same waveform was up around 0.3-0.5, it would be perfect.
To me, that's an unambiguous diagnostic indicator - replace Sensor#2

I don't understand exactly what the "equivalence ratio" means, so I ignored it.

 

[Rivman1243]

Right, think you got it.

O2 1x1 V graph = Bank1 Sensor 1 (upstream, closest to engine) always actively banging rich, lean, rich, lean.
O2 1x2 V graph = Bank1 Sensor2 (downstream, farthest from engine) should be more of an average stochiometric value.

Bank2 has no meaning for the Landcruiser because Bank1 and Bank2 are Y-piped together before O2 sensors and cats.
I have a GS300 with a separate cat for Bank1 (cyl. 1,2,3) and Bank2 (cyl. 4,5,6) and so it has 4 O2 sensors.

Your O2 1x1 V graph looks fine, I think. The full scale swing proves the sensor is working, regardless of anything else.
Your O2 1x2 V graph (if truly representative) looks to be attenuated and sort of stuck near "lean".
Looks like it's trying to work, but can't quite, like it's coated (guessing here).
To me, that's an unambiguous diagnostic indicator - replace Sensor#2

I don't understand exactly what the "equivalence ratio" means, so I ignored it.

I have an exhaust leak. That's why its reading the way it is. It was also -10°F

 

[Bambusiero]

I have an exhaust leak. That's why its reading the way it is. It was also -10°F

Oh, sure, that could explain it. Extra air leaking in, leaning the sensor a bit?

 

[Heckraiser]

So I got wildly varying graphs depending on driving condition. I took a bunch of screen captures, but honestly can't remember what is cruising at 40mph, what is idling, etc. Except the last screen capture is idling.

 

[Heckraiser]

I mean the last of these ones is idling in front of my house.

 

[Bambusiero]

@Heckraiser - just trying to read between the lines and interpret your graphs & guessing bit...

O2 1x2 - it wiggles some, but always down near zero (the lean end).
Only in two cases did it struggle up into the middle.
I don't think it's responding normally.

Conclusion - replace O2 sensor #2.

OR - you have an an exhaust leak around the cats that's sucking in some air - like @Rivman1243.

Now, having something to compare to - after you replace, you should see a distinct difference in behavior.
If not, then you know to look elsewhere.

I think probably the best situation for making judgements on this kind of thing is mid-load "nominal operation", like cruising steady state 45-60 mph. The ECU is happily running things closed loop.
Idling and full throttle are exceptions to it's normal rules, so avoid using that to figure things out.

 

[Rivman1243]

Do you the test results option on your home screen in the torque app?

If you do go there and see what pops up. It should tell you the response time of your o2 sensors.

 

[Heckraiser]

@Heckraiser - just trying to read between the lines and interpret your graphs & guessing bit...

O2 1x2 - it wiggles some, but always down near zero (the lean end).
Only in two cases did it struggle up into the middle.
I don't think it's responding normally.

Conclusion - replace O2 sensor #2.

OR - you have an an exhaust leak around the cats that's sucking in some air - like @Rivman1243.

Now, having something to compare to - after you replace, you should see a distinct difference in behavior.
If not, then you know to look elsewhere.

I think probably the best situation for making judgements on this kind of thing is mid-load "nominal operation", like cruising steady state 45-60 mph. The ECU is happily running things closed loop.
Idling and full throttle are exceptions to it's normal rules, so avoid using that to figure things out.

Should I be concerned that 1x2 was bouncing up and down like 1x1 when it did reach the middle of the chart? Is that normal, or should 1x2 look relatively smooth?

 

[Rivman1243]

Should I be concerned that 1x2 was bouncing up and down like 1x1 when it did reach the middle of the chart? Is that normal, or should 1x2 look relatively smooth?

Try connecting to a newer vehicle and watch the same parameters. It should be fairly smooth but that's only if the cat is at operating temperature. The whole drive cycle you were following is to get all of the monitors to complete the most important part of that cycle for the catalytic converters to complete is that you start with a cold soaked engine and let it idle for 10 min before you do anything.