Evap System Mon

[GlennSullivan]

ODBII drive cycles are a PITA and generally a good way to get into an accident when performing one.

Mesaguy's process is very accurate for Ford vehicles. I found that Chrysler vehicles were much easier.

 

[gtr09]

I really hate the Evap Test. Everyone does.... Its designed to approximate "real" driving, but NO ONE in California drives this way. The only people driving 55MPH (I know, I am there with them when running this program) are the illegal aliens who do not want to get pulled over for any reason, in the right hand lane. The test is actually VERY stressful to run in Speeder-ville CA, because 55MPH can get you killed. Even the Semi's want you running 60MPH, but 59 seems to work with them, and I have found that to work OK. But better to stay closer to 55MPH if you can.
- The Nissan Manual also mentions specially NOT to use the Cruise Control. I don't know if that is because their cruise control may accerate at times harder than the Evap Monitor will allow, or if it is a CARB/Fed. standard requirement, but no Cruise Control.

Wow, every time I think CA or CARB has reached a new level of unsurpassed idiocy I find I'm wrong again. Thanks for sharing all of that info! I just learned about "permanent" codes last week after I swapped new port injectors in and I left one of the fuel rail electrical connectors was not quite plugged in all the way. Started it up, sucker ran on 3 cylinders pretty smooth actually. Realized what happened, took intake off again and plugged the rail in all the way. But I got codes I couldn't remove of course. Did a little reading and all I saw was "drive 200 miles and have to have some overnight cool downs during that". I had no idea it was this absurd. I don't think they'll ever go away unless I make an effort hah.

But, I keep my cars tagged in a state with no emissions, guess I can add 1 more benefit to that.

 

[MesaGuy]

If you have hard codes, then you generally need to put on a OBD-II, and clear them. Of course, when you do that, then all of the emissions state is automatically cleared. e.g., clear any fault code, and all emissions state is set to incomplete monitors. That is CA and Fed. law, so all the vehicles do that. (That is the anti-cheating mechanism). And then, you get the privilege of running the proscribed test program above.

For some (very few) people, just driving a while (usually 2 weeks to a month), will eventually hit each of the sub-components of the emissions monitors. The ones that typically take the longest to get happy are the EVAP monitor, Catalyst (CAT), and Oxygen (O2) sensor. On some vehicles, the EGR and Heated Oxygen Sensor monitors are added to the list.

But for me, its almost always the EVAP monitor. And that one is difficult because it cares about the cold-soak requirement, the 1/2 tank requirement (it measures EVAPORATION Gas fume vacuum condensation system performance, hence the tank has to be 1/2 full, so that there is plenty of room for vapor), and the CAT monitor.
But if following the procedure above, you can crush all the monitors in the one session, they will all set from INC to OK (assuming your care is in correct working order).

I obviously recommend getting an OBD-II monitor. Plenty of them now for your iPhone or Android phone that work wirelessly (usually bluetooth now), or you can get a cheap (but adequate) one from harbor freight. HFT seels a bluetooth (phone use) one for $60, and a low end (codes only) unit for $40. Those are both worth buying and throwing in the trunk..

Units with ABS brake codes (more), SRS (Airbag) codes (more), Live Data capture (more), and "Fix recommendations" (various branding) (more), and Live Data graphing (more+).. I work on my own car, so the +ABS,+SRS(airbag)+LiveData makes sense. The Fix Recomentations basically just give you "English" two sentence explanations (that you can otherwise get using Google on a laptop to lookup Pxxxx code causes and meanings. The internet explanations are generally more complete, but Fix Assist lets you do it in your garage to some extent (or out on the road).

If all you are trying to do is pass emissions, then the $40 units work fine. Amazon sells low end units with OBD-II codes, and print/clear codes options for $20, and even $10. These units all work just fine.

 

[gtr09]

If you have hard codes, then you generally need to put on a OBD-II, and clear them. Of course, when you do that, then all of the emissions state is automatically cleared. e.g., clear any fault code, and all emissions state is set to incomplete monitors.

The hard codes, (actually called Permanent codes) can't be cleared with a scan tool. That's what I meant when I said I could not remove them. Only getting those monitors to complete will do it. I've had code readers for 25 years and I do all of my own work as well. I just haven't worked on a modern enough vehicle that also had one of these permanent codes and I don't have to do emissions testing so by sheer luck I never came across it. On my GTR (2009) some of this crap is just turned off in the ECU so I never dealt with it there, either. I'm just going to ignore them, monitor will complete or it won't but not worth my time to force it.

 

[GlennSullivan]

Also keep in mind that disconnecting, changing or having your battery go dead (such as sports car only driven in summer) will also change the status of these sensors to "not ready" and force a drive cycle test if you need to go through emissions testing near term after that. Right after ODBII arrived on the scene in 1996, I because a huge fan of the Battery Tender products.