Engine Cycle Suggestions - Emissions Rejected

[SteelGreyM]

Well

I let the car idle for 10 minutes with no effect. Then drove it around for 5 minutes trying to get o2 to be ready and funny enough EVAP finally says ready.

Few min later o2 says ready and I raced over and passed emissions 👌

[SteelGreyM]

No pending codes
No stored codes

Day 1: everything ready except o2 sensor and secondary air system

So later that day I do the procedure for getting o2 sensors ready and everything is ready to go

Day 2: I wake up drive straight to emissions and what do you know my O2 is ready but EVAP and SAP not ready. SAP will never be ready cause it's gone

Now my o2 and my EVAP (and SAP) show not ready. Why do they keep resetting so annoying

[zzyzx85]

Do you have any pending codes?

[SteelGreyM]

Yes but yesterday it was ready and today it's not. How does that happen?

[eacmen]

I think EVAP monitor is easiest to set when fuel level is around half a tank.

It is evaluated during a cold start. Idle car for 3 minutes. You need at least two cold starts to get evap ready iirc.

Google around plenty of posts on this topic.

[zzyzx85]

This worked for me on more than one occasion. Had to do it in the dead of night to get it completed without interruption with hazard blinkers on.

SteelGreyM: I generally followed the above procedures to get my monitors ready, except I ended up idling for much longer (like 5 minutes) to get my SAP to set. I think what really did it was relaxed driving on the street (ex. calm accel and decel) and not exceeding 60mph and 3000 rpm during the drive. I avoided going on the freeway because people around here tend to drive way too aggressively for me to be doing 55mph safely.

[SteelGreyM]

Unlike popular belief, disconnecting the battery does not reset the monitors. Clearing codes, swapping sensors, clearing adaptations, getting and having stored faults, does. You can plug things into obd port and run scans, that's how you check that the monitors are set so you are not surprised at the testing center.

You need to also understand what happens during the "drive cycle". Like if your SAP or EVAP are not set, you do not need to drive the car, because those specific monitors are only tested and set during a cold start. If your o2 are not set, you don't need to idle the car from cold start for 5 minutes, because o2 monitors are only tested and set during a constant speed drive on the highway. You CAN stop at stop signs and red light on the way to an open road/highway (again unlike popular belief). You can accelerate/decelerate, etc, just the o2 test starts once you are at constant speed. RPM and MPH limits are true. The "run all red lights" on the way to highway are not.

I think people bend over backwards a bit too much following those strict rules when they dont need to. Isolate what you need to set, understand what condition is required to be met for it to set, and follow it.

The 20min cruise around thing...depends. If your hardware is in good condition (fresh sensors etc), it can set a lot quicker. I had my obd2 plugged in during the drive, running a scan via obd fusion app, and my o2 monitors set within 3 mins, so I got off the highway, no need to keep driving for 20mins.

I just did all this for my CA smog test, I recorded videos to post on youtube explaining things, but I have no time to edit at the moment.

Sent from my SM-G950U using Tapatalk

Yesterday my EVAP was ready but I failed emissions today because it wasn’t ready. What is the exact procedure for getting evap to say ready? Idle cold start for 3 minutes?

[gaiakai]

I tried numerous drive cycles w/o success. I was running out of time so was looking at all options. I tried a product called "Cataclean". I wasn't expecting it to work but after pouring it in with a 1/4 tank of gas left and a short drive, my CAT monitor set itself to OK. Took the car in and it passed smog w/o issue. So relieved.

My car has 79k so I was confident i wasn't having an issue with actual catalytic converter.

I know this is a necro (sorry) but I wanted to thank you for this. After multiple drive cycles at 3am my stubborn CAT monitor only set to 'ready' after the cataclean. I was about to pay $200 for a smog repair shop to go through the drive cycle themselves on their own dyno to make it ready. $200 is a lot of chicken nuggets, so again, thank you! 141k stock M3 for reference.

[Tbonem3]

I also believe EGT was removed or ignored by smog computers several years ago.

[martin.oconnor]

Evap is not needed to pass in CA, just fyi.

https://www.bar.ca.gov/Industry/OBD_...ence#readiness

Ah - I thought it was all of them in CA. Good to know. (Now just need to sort the secondary air, which has not reset despite multiple cold starts. I've had some related pending codes in the recent past so might need a new secondary air pump.)

[heinzboehmer]

In CA, all modules have to be in the ready state to pass.

Evap is not needed to pass in CA, just fyi.

https://www.bar.ca.gov/Industry/OBD_Test_Reference#readiness

[martin.oconnor]

SAP will only go ready on a cold start. EVAP had to be less than 3/4 tank to go ready.

I wes able to pass in MD without EVAP going ready.

Yup - my tank was 100% full so the preconditions for that test were not met.

In CA, all modules have to be in the ready state to pass.

[eacmen]

I used this approach a few days ago and it succeeded in getting my catalyst and heated-catalyst tests into readiness.

(Driving at 55mph in the slow lane was a revelation. There appears to be a large class of people who actually do it full time.)

Still having issues with evaporation and secondary air tests, but that is another story.

SAP will only go ready on a cold start. EVAP had to be less than 3/4 tank to go ready.

I wes able to pass in MD without EVAP going ready.

[martin.oconnor]

I used this. It worked. Done and drove right to the emissions stations and success. Choose the right "not crowded" road that you don't have to brake, speed up to merge or otherwise fall outside the limits.

....

I used this approach a few days ago and it succeeded in getting my catalyst and heated-catalyst tests into readiness.

(Driving at 55mph in the slow lane was a revelation. There appears to be a large class of people who actually do it full time.)

Still having issues with evaporation and secondary air tests, but that is another story.

[marksae]

What does catalyst have to do with pre cat o2s?

From what I've read, the ECU compares the reading differences between the pre-cat and post-cat o2 sensors to determine the cat efficiency.