andrewdonald1

Gents:
2004 C5Z.

I went in to test emissions yesterday morning but could not test since the system has not been through enough duty cycles to warrant accurate scanning history for emissions.

I had the infamous P0492 in the past and I've been nursing it along using the "shoot" the cleaner down the secondary air injection check valves method.
I cleared the DIC of history codes before going in "thinking" I was being smart about the whole thing. I only had the P0492 code.

I guess it clears the duty cycles as well which makes sense now.

Being that I have to pass emissions by next Wednesday to renew my tabs, I went ahead and got the parts to replace the two check valves, replaced them yesterday (long day BTW), and took the beast out this morning knowing that it needs to go thru a few warm up cycles.

Globally I am betting all the systems need to now run through some cycles as well, not just the PCM - although I only had to reset the PCM code above.

Anyways: anyone have any idea on:
[a] if its only the PCM that need to go through a few duty cycles - how many? I would assume its got to be at least a couple warm up cycles at minimum for the secondary air injection system.
[b] any others that may need to be considered?

I am trying to plan my next few days to ensure I get enough mileage on the car to make sure all the systems will now "green light" from a duty cycles perspective for emission testing.


Here's what the emissions check sheet says that they gave me:

On-Board Diagnostic System "Not Ready" for Testing.

The on-board diagnostic system requires that after resetting or clearing the memory on the vehicle's computer system the vehicle must complete a manufacture's drive cycle. During the drive cycle, the system performs a test of specific emission control components and sets the readiness monitors to ready.

Normally, the on-board diagnostic system checks the function of specific emission control components during daily driving. If the vehicle was recently serviced or the vehicles battery was disconnected or experienced low voltage then the vehicle may merely need to be driven a distance of 25 to 50 miles over a two to three day period. This normally allows the on-board diagnostic system to complete its test and allows the vehicle to be "ready" for testing. Otherwise, you may need to check with your dealer or repair facility.

A vehicle will be "Rejected" until the readiness monitors are set to ready.
State regulation requires that while a 1996 to 2000 vehicle is running, if the check engine light is off and there are more than two readiness monitors "Not Ready", it cannot be tested. On 2001 and newer models, the limit is no more than one readiness monitor.

Contact your dealer or repair facility if you have any questions about how to complete a drive cycle for your vehicle.

Toque

Andrew:

I ran this routine twice and passed. Also make sure your fuel tank runs under 1/2 tank so that the EVAP test runs and goes to a READY state.

http://www.obdii.com/drivecycle.html

As per GM :

To perform an OBDII Driving cycle do the following in this exact sequence...

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.

7. 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.

8. Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

tblu92

Ok they are not called "duty cycles" but are called " drive cycles"
Typically you will need to drive approx 50 miles or so and must do at least 2 dead cold starts-- to complete the drive cycles
The drive cycles will make the car go thru the "READINESS TESTS"
Anytime you dis-connect the battery or dowload a tune the readiness tests are all reset to "Not Ready" again-- The P0492 is a common code for an AIR check valve that is carboned up or clogged-- ( pass. side) you can try to remove it and clean with brakeclean and see if it leaks by blowing into it--If it is beyond just cleaning then you'll need to replace it
Another way is to go to a tuner with HP or EFILIVE and they can turn off all the enablers for the entire AIR system and the AIR readiness test will imediately set to "ready"

dougbfresh

It's the I/M monitors not passing (Heated O2, Evap,...)-these tests run at different times. If you clear ANY codes or remove power, they ALL reset.

You can see these with cheapy OBD scanners like Actrons.

andrewdonald1

Ok, I plugged in my Autoenginuity software and it says I have 6 of 8 IM Monitoring tests complete.
Only 2 left are:
[a] Evap System Monitoring - I just filled up so I think I need to burn off some fuel for the next 2 days of cold starts to allow a Wednesday test
[b] Secondary Air Systems Monitoring - suspect I need a couple more cold starts.

dougbfresh

There you go, you'll know exactly when you can run it through emissions now!

Toque

Yes..... EVAP got me before. You need to run your tank down to about 1/2. The EVAP test will run somewhere under 3/4 tank I have heard. It worked for me.

Toque

andrewdonald1

Passed Secondary air monitoring.

Just got under 3/4 tank. I'll see if I can get it tomorrow.

Boy did I learn a lesson about clearing codes..

andrewdonald1

I passed!!! Only 7 of the 8 IM Monitors are ready, but in WA that's good enough for Govn't work...literally in this case.

That pesky Evap test is a b*tch. I tried to get it this morning (even got up early to make sure traffic was fine for the test) and I still didn't get it.

I am just coming down to 1/2 a tank now (this morning was just under 3/4 tank), so maybe that was my road block.

But I don't care now, I am good for 2 years!!! Party Party on...

Bill Curlee

Something else that will screw the emissions ready is a weak/old 12 VDC battery. When you crank the engine with a weak/old battery, the battery output voltage will drop below 9 VDC and BINGO! The emissions is NOT ready cause the PCM shuts down due to low voltage.

BC