Pontiac G8 Forum banner

1 - 11 of 11 Posts

·
GWS Pontiac
Joined
·
634 Posts
Discussion Starter #1
I have less than 5000 miles on my car.

Last year, I replaced the battery. I'm not sure how few miles I drove the car since that time.

Six years have gone by, it's time to join in for the joys of SMOG.

Apparently, I failed because the cars computer was "not ready."

The tech suggested I drive it around for a while, 50-100 miles or so...

I had never heard of this before today, so I did a little research to try to nail down what, exactly, the computer needs to do to establish itself as "ready" and readable for the SMOG machine.

Here it is, from obdii.com:

General Motors Driving Cycle

A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.
To perform an OBDII Driving cycle do the following:

  • Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
  • Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
  • Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
  • Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
  • Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
  • Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
  • Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
  • Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.
http://www.obdii.com/drivecycle.html

Learn something new everyday...
 

·
Registered
Joined
·
100 Posts
I cleared a code on my Grand Am a couple years ago before going to smog and learned about drive cycles then. I managed to get through smog after replacing the downstream O2 sensor but the light came back a few weeks later. Had to replace the catalytic converter to fix it for good. Hasn't thrown the code since then.

Trying to make the car go through the drive cycle is a huge pain. Especially when everyone on California roads is traveling 75 mph...
 

·
GWS Pontiac
Joined
·
634 Posts
Discussion Starter #4
I'm trying to figure out if each step can be treated individually.

- idle from cold, with AC and rear defrost, for 2:30

- accelerate (1/2 throttle), without AC and rear defrost, to 55 mph and hold for 3:00

- decelerate from 55 to 20 mph without the use of shifting, brakes, or clutch

- accelerate (3/4 throttle) to 55-60 mph and hold for 5:00

- decelerate without the use of shifting, brakes, or clutch

NOTE: If battery was disconnected, it may take 5 sets of these driving cycles to determine the state of the catalyst to be "ready" for an emissions test

-----------

I've read where people have driven for hundreds of miles to get their system "ready."

Overall, I find this process a bit disconcerting.

The irony that I might need to drive my car a few hundred miles, burning gas and creating emissions to pass a SMOG test... :nuts:
 

·
Registered
Joined
·
2,001 Posts
Man, you guys make drive cycles seem so complicated. Haaa.
 

·
GWS Pontiac
Joined
·
634 Posts
Discussion Starter #7
According to Dash Command...

I have 7 diagnostic monitors in the drive cycle of this M6 GXP.

Currently, I am passing 5 of them, or they are in a "ready" state:

  • Misfire Monitoring
  • Fuel system monitoring
  • Comprehensive component
  • Oxygen Sensor
  • Oxygen sensor heat
2 of them are in a "not ready" state:

  • Catalyst monitoring
  • Evaporative system
Does anyone have any idea which of the drive cycle tests I should focus on to pass these last two diagnostic monitors?

I'm thinking that the acceleration/deceleration processes would be the keys, here, but I am not sure. Can anyone offer any insight?

Also, do you think, with it being a manual shift, the car would not need the 55/60 mph test as long as the RPMs were in the right range?

Your thoughts?
 

·
GWS Pontiac
Joined
·
634 Posts
Discussion Starter #9
Well, after 100+ miles and keeping the driving cycle in mind, I passed SMOG.

Dash Command registered a pass on Catalyst monitoring but continued to fail the Evaporative system.

For $hit$ and giggles, I connected the Dash Command to my 2011 Caprice. It read the same 6 "ready" tests along with the same Evaporative system fail as with the G8. Odd thing is is that the battery has never been disconnected in the Caprice... must be a Dash Command issue.

Overall, this was quite a bit of a hassle for just disconnecting the battery on an OBDII vehicle...
 

·
Registered
Joined
·
1,641 Posts
Look out, the "evaporative system fail" hit a raw nerve for me (really a nightmare)! A number of us had a vap valve fail which is up by the gas tank. But it triggered a specific code other than the "not ready" one. It's a $150 part but the GM method to get at it is to drop the tank which is a lot of labor $$. So $800 later it was fixed!

Although it's part of the emissions system, it is not covered! At the time some members here figured out how to get at it through the wheel well. The valve was tricky to remove and small hands helped. Thought I bring this up just in case. Of course a search will find the gory details.

I couldn't get into doing it myself because my inspection ran out trying to figure out what was going on and the guys that figured it out were also in the middle of it so the details were only starting to surface on the forums.

Also bad gas gaps were also part of the mess at the time.
 
1 - 11 of 11 Posts
Top