Drive Cycle
#21
01-23-2013, 11:38 PM
lol, i think i've figured this out.
new member john w has a 2001 truck. he took it in for some kind of inspection required by his state, which we don't know, but it doesn't matter either. we'll assume its California Emissions testing. now, the inspector reports that he can't complete the testing, because the PCM reports that the battery has been recently disconnected, and it has not yet recorded enough data for it to possible set a CEL. So the inspector told the truck owner, john, that the emissions monitors were not ready, and that the computer was not in "ready" mode as defined by his equipment.
here's the answer.
Welcome to DF. About 100 miles.
LOL.
here's a better answer. about 1/2 way down this page.
http://www.aa1car.com/library/us796obd.htm
cut/paste for the lazy.
RUNNING AN OBDII DRIVE CYCLE
Suppose you have "fixed" an emissions problem on an OBDII-equipped vehicle. How can you check your work? By performing what is called an "OBDII drive cycle."
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you have erased any trouble codes from the PCM memory, or after the battery has been disconnected. Running through the drive cycle sets all the system monitors so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
new member john w has a 2001 truck. he took it in for some kind of inspection required by his state, which we don't know, but it doesn't matter either. we'll assume its California Emissions testing. now, the inspector reports that he can't complete the testing, because the PCM reports that the battery has been recently disconnected, and it has not yet recorded enough data for it to possible set a CEL. So the inspector told the truck owner, john, that the emissions monitors were not ready, and that the computer was not in "ready" mode as defined by his equipment.
here's the answer.
Welcome to DF. About 100 miles.
LOL.
here's a better answer. about 1/2 way down this page.
http://www.aa1car.com/library/us796obd.htm
cut/paste for the lazy.
RUNNING AN OBDII DRIVE CYCLE
Suppose you have "fixed" an emissions problem on an OBDII-equipped vehicle. How can you check your work? By performing what is called an "OBDII drive cycle."
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you have erased any trouble codes from the PCM memory, or after the battery has been disconnected. Running through the drive cycle sets all the system monitors so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
For around a hundred dollars the dealership will smoke test your evap system. That would narrow down the possibilities. I hate having my CEL on but money is kind of tight. I erase the code and then drive about 25 miles hoping the light doesnt come back on. They did make me replace my gas cap last time, but that did not fix my code problem
Last edited by gdstock; 01-23-2013 at 11:40 PM.
#22
01-24-2013, 08:29 AM
#23
01-24-2013, 08:45 AM
Veteran
I'm not sure if this method will damage anything or not, but I've heard that a way to find an evap leak is to start spraying starter fluid along all the lines, canisters, etc. in the system with the engine running. When you hear the engine rpms start to increase, you've found your leak. Again, not sure how well or if this works, but it might be a way to save a couple bucks on a smoke test.
#24
01-24-2013, 11:38 AM
I'm not sure if this method will damage anything or not, but I've heard that a way to find an evap leak is to start spraying starter fluid along all the lines, canisters, etc. in the system with the engine running. When you hear the engine rpms start to increase, you've found your leak. Again, not sure how well or if this works, but it might be a way to save a couple bucks on a smoke test.
Whether this would work or not would depend on if the point where the leak is has a higer or lower pressure that 1atm. If it was a vacuum, yes, but if it pressurized, the starting fluid will not work.
#25
03-18-2013, 10:00 AM
chrysler drive test
hey guys ,,just wanted to post this on the drive test ,,around thanksgiving of last year we had to replace the tps and the battery in my sons 02chrysler mini van ,,In january he needed to get the van inspected and needed the emmision test,,he drives the van every day and travels between 50 -100 miles a day round trip..and when he took it in it came up not ready for testing ,,lol,,lol,i know he's driven it at "least" 2000 miles simce we replaced the battery and tps and last week he tried again and same thing ..not ready ..real PITA,,lol..he drives in city and on the highway everyday and does go thru the speed ranges and warms it up every morning ,,and still the o2 and the catalyst aren't ready for testing ..he's been in the testing garage 4 time since january,,ya'd think driveing it that much should have reset the sensors ,,so my advice is don't change the battery when it dies if ya ever want to pass the emmision inspection!!lol..lol..gonna try the test you guys have posted and see if it may help ,,the check engine light is not on and it seems to be running fine ..
crazy
crazy
#26
09-15-2014, 03:49 PM
Drive cycle issues
I wanted to post what I found for those of you with smog issues, specifically unset monitors.
In Nevada you are allowed one unset monitor or sensor and I had two, OBD evap and O2 monitors. I have a Centech scan tool that shows if monitors are not ready. I drive a 2012 Dodge journey and was panicked with expired registration. The dealership and smog shop both told me to drive 100-200 miles while mixing highway and street driving. After all that still unset.
As I was aggravated I drove at 35mph and punched the gas pedal 3 times, just enough to rev but not gain speed and went home. After cooling off for an hour (me and the car) I scanned it one more time and the evap monitor had set!
I danced at the smog station as I passed the test.
In Nevada you are allowed one unset monitor or sensor and I had two, OBD evap and O2 monitors. I have a Centech scan tool that shows if monitors are not ready. I drive a 2012 Dodge journey and was panicked with expired registration. The dealership and smog shop both told me to drive 100-200 miles while mixing highway and street driving. After all that still unset.
As I was aggravated I drove at 35mph and punched the gas pedal 3 times, just enough to rev but not gain speed and went home. After cooling off for an hour (me and the car) I scanned it one more time and the evap monitor had set!
I danced at the smog station as I passed the test.
#27
09-15-2014, 04:07 PM
