LS1GTO.com Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
120 Posts
Discussion Starter #1
I am having a hell of a time completing a drive cycle so my O2s and Evap are ready so I can get my car inspected and tags renewed. I have driven it to work and home for two days, gone to lunch and to a car meet, drove around and such. I have found the GM recommendation to complete a driving cycle. I found one old discussion on here that a couple people said they used the instructions below and it worked. I have tried a couple times to no avail.

Does everyone that uses the GM instructions live on the highway? How do I go from idling for 2.5 minutes to half throttle to 55, hold for 3 minutes and so on without my garage exiting straight to the highway. It takes me atleast 10-15 minutes, after the idle sequence, to get somewhere near my house that I can do the 55 mph instructions.

Any other suggestions on how to complete a driving cycle?


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.
 

·
Registered
Joined
·
794 Posts
Park it near the freeway on ramp all day then go do the cycle on a cold start at midnight.

Not really but there doesn’t seem to be an exact science to it. I’ve always been able to get most complete on the warm up then get the 02s on the drive. Evap always takes the longest but around here we can have 1 monitor not set.

I set cruise control on the drive and never could get a full decelerate bc of traffic. Regular driving on surface streets would set the rest.
 

·
Registered
Joined
·
120 Posts
Discussion Starter #3
Park it near the freeway on ramp all day then go do the cycle on a cold start at midnight.
That was my next plan. 😆

Ya, I have been taking back roads to work in the morning, so I get the stop and go. Then I take the freeway home. I have driven around and went to a car meet lastnite. All to get a combination of driving. Still nothing.

Without doing the 2.5 minute idle at first, my O2 heater circuit already showed good. Just have not been able to get the O2s and Evap to complete. I think all I need is the O2s to pass. Just frustrating.
 

·
My other car has wings
Joined
·
439 Posts
I made the mistake of changing my battery about a week before inspection. That cleared everything so I had the same problem as you. I have HP tuners so I disabled the Evap reporting. We in NC are allowed to have one 'NOT READY' system but not more. Went back after the new tune flash and it passed.
 

·
Registered
Joined
·
120 Posts
Discussion Starter #6
Finally the O2s are on. Someone turned off the testing, I believe it’s called. Whoever tuned the car before I got it, turned all kinds of stuff off. A buddy did a quick tune and the car is running and driving better.
 

·
Registered
Joined
·
120 Posts
Discussion Starter #8
They also had the front O2s turned off and the rears on. Maybe that was part of it.
 

·
Registered
Joined
·
120 Posts
Discussion Starter #10
That would make it run like crap
That's what is strange, it didn't. It definitely runs "cleaner" but it never ran bad. From my reading, some people do it if they track the car mostly. Since I had to replace the trans, that might be the case. After having a built trans put in and a stall, we adjusted the lock up and shift rpms and it drives much nicer now. Shifted too soon into second before. So I guess I am glad this issue happened because the car is even better now.
 
1 - 10 of 10 Posts
Top