California Smog - Stubborn Issue

You're the second person to mention this on this thread, so a new OBDII connector may be in order. Any info you have on this would be great.

 

So I used to be a CA smog tech and my usual monitor set procedure went a little something like this:

1. Cold start. Coolant temp needs to be close to ambient air temp which is ideally 50-80F.
2. Let it warm to closed loop. O2 sensor will be switching high/low about once per second in your scan tool and coolant will be at temp. This is an O2 test that is part of the catalyst monitor.
3. A little town driving easy/moderate throttle. Coast down to stops as much as possible for EVAP.
4. Highway cruise... 3-5 min around 50-55 mph and as steady on the throttle as you can. That era isn't great about faster because the national speed limit was 55 until '95. This is evap and catalyst and some vehicles are picky af about this one.
5. If the monitors haven't set, shutdown and let it cool. Don't turn it on for at least a few hours. This is for evap offline tests that can be wonky.

This was good 95% of the time and if not, it was some weird requirement or a marginal something that wasn't throwing a code but wasn't good enough as a dependency to pass something else. This is also the reason CA used to only require all but 2... getting them to all set can be a bitch and we only worried about them if it was confirming a repair.

 

Good info ^^^^

Dealing with a stubborn single monitor can be frustrating. I have never found a printed answer to my question, each time the vehicle starts from either cold or hot, will it skip all completed monitors and just check the incomplete one if the conditions are set. There have been times where I "work" on the INC monitor via the drive cycle with no effect. Its like it is being skipped over... If I reset the PCM and start over that troublesome monitor will complete. Did I drive it different this time than the prior 5 times or ?

 

So I've tried everything suggested in this thread, plus the other things I've mentioned, but the Cat and Evap still appear as incomplete. The shop I worked with suggested replacing the ECU, but I'd rather that be an action of last resort.

Thinking my next step is to start replacing O2 sensors (the downstream one first). In California, I can have the Evap or Cat register as incomplete, but not both, so I'm focusing on the Cat.

 

Very frustrating.

 

Hi all, OP here. I finally have some free time to address this after a crazy few weeks. So I'm trying to decide which INC (Incomplete) items I want to troubleshoot / fix: CAT or EVAP. Remember I only need to fix one to pass smog in California.

Which would you choose? I figured it might be simplest to start with CAT and start replacing O2 sensors, but I'm certainly open to suggestion. Thanks!

 

I think I would have to make a judgment call based upon which I felt was easier to fix, cheaper to fix, or easier to track down.

The 02 sensors are not cheap, but the job is pretty straight forward. In my experience, it's best to go with the OE sensors. Others sometimes don't work well. check all the wiring, and reset the Computer.

I feel like we are all pulling for you here! Damn CA smog!

 

Had this same issue with my ‘00, tried all the same cheap steps like cataclean etc and could never get it to go.

My cat then was stolen in the night, had a new one burned on, everything worked after. Maybe a bum cat?

 

Following up... I replaced both O2 sensors with OEM ones. I'm still getting an INC. It's discouraging. I wonder what my next steps might me for either CAT or EVAP.

The irony is that the truck is running better now than since I bought it.

 

What about starting all over? Clear the memory by resetting the computer.

1: before parking the truck for the night, make sure you have less than 3/4 tank but more than 1/4 tank
2: reset computer and remove gas cap for ~5 sec to relieve any pressure and tighten gas cap back on
3: let the truck cool down and sit overnight without doing anything to it
4: early morning (6 or 7am), remove gas cap again in case pressure builds overnight and tighten back on. Start truck and immediately turn on AC and fan speed at max. Let the truck idle for 15 minutes with AC on without doing anything else.
5: after 15 minutes, go for a drive. Stick to surface streets with stop and go traffic for about 10 minutes and allowing the truck to roll to a stop without applying the brake when possible
6: pull over and check computer status
7: if computer is not ready, I typically hit the highway for about 10 miles, keeping speed between 65/70 and this should do complete all the drive cycle

this seemed to work for me when I smog.

BTW, in CA you are allowed 1 pending module (not ready status) which is the EVAP. Everything else must be ready.

 

@02hilux I assume by "reset computer" in your Step 2 above, you mean disconnecting the battery for a while, correct?

 

or use a code scanner even though there is no pending code

 

Follow up: without me doing anything other than driving the truck around for maybe 50 miles after I swapped the 02 sensors, the CAT finally read as "ready" yesterday I'm assuming the new Denso sensors did the trick. Taking it to be smogged today! FYI: The EVAP still registers as "not ready".

 

I can imagine the joy, after weeks and a thousand miles of trying everything, I was 1 day away from registration being overdue so I was ecstatic when my Scangauge finally showed the system being 'ready'. I drove that thing straight to the smog shop without passing go, lol

 

And she's passed smog! Thanks for your help everyone!

 

Nice job. Time to grab a beer and relax.

 

Kind of old post but this frustrated the heck out of me and I figured I should leave this info. I just went through this last week on my 98. I spent an entire tank of gas and 6 hours of different drive cycles. Frustrated I parked it and started doing more reading on my tablet. Found a few more methods/cycles and started testing them. What finally got the Cat monitor to go "complete" was finding a steep hill, turning the truck off at the bottom, starting it up, heading up the hill without sudden acceleration getting into 3rd gear and leaving it in 3rd while doing 50-55. Within 3 minutes(I was timing everything with my dash tablet) my Cat monitor flipped complete. My evap is still incomplete but that's not required here in Cali.