What is the DRIVE CYCLE for my 2001 CHEVY S10 PICKUP TRUCK..aka How long do I have to drive it until it resets and will pass Emissions

I had a similar problem with my Chevy Malibu! NEW BATTERY = FAIL SMOG TEST in California!

I needed to 'freeway drive' as much as possible for four days before the computer would 'reset'... THEN it passed 100%

Anthony
(SAY "Thank You"!)

Did you recently clear the trouble codes or disconnect the battery? Once all codes are cleared, the computer will not display systems 'ready' until they go through an evaluation cycle. Some of the systems require a certain number of drive cycles before they will display 'ready'. A drive cycle is usually starting the engine from a cold start (based on coolant temperature) and driving until certain conditions are met. I don't know what the requirements are for your car, but my 2003 pickup truck requires more than 10 drive cycles before it will make the O2 sensors and evaporative emissions 'ready'. Most states only require that a certain number of systems are showing 'ready' to pass emissions certification.

Drive cycles can be done in about an hour. 15 minute intervals.
First at highways speeds. Second at 45 MPH. Third at 30 MPH. Fourth at stop and go traffic. So from the highway to the city. Or replicate it on country roads. Just a note. drive cycles don't really effect emissions. You may won't check state requirements, or take it to another shop. or ask another shop.

you must not clear codes or unhook battery after doing what they call a drive cycle which resets monitors to a ready state. http://www.lhforums.net/forums/showthread.php?2755-OBD-II-and-your-Next-State-Inspection
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Disconnecting the battery resets the PCM - engine computer ,an the emission monitors . A drive cycle has to be done to get the monitors to run an hopefully set. That's all you need to do is drive it for few days of different driving conditions - city , highway ,from cold start . google GM drive cycle . OBD Monitor Not Ready

If your truck is old enough, it could be what is called grandfathered in, meaning it doesn't have to pass emitions. Try getting a 2nd opinion.

Try pulling the battery terminals,if not you will have to have it cleared

Wasting your time driving it
Check for codes
Look at all data
Find a problem & repair

Have exhaust gas reading taken in a repair
shop, & use that to diagnose and repair

I dont think it matters how far you drive as long as it gets completly warmed up and then gets completly cooled down.
It sounds like you already know this but But for other readers benifit I will add that there are some details that can make the process quicker.
this only pertains to 1996 on up vehicles that the check engine light is NOT illuminated.
When preparing for emissions tests after unhooking your battery, there are readyness tests that have to be completed before your truck is ready to be tested.

• Basicly in a nut shell, all they do at the emission station is to make sure that your check engine light is not coming on because of any issue.

The way they check this is observe the light before and after they start up your vehicle. If it goes out after starting then your good.
except for one thing, they hook up to your trucks computer and see if your computer has been reset. if so they confirm that your truck has ran its readyness tests.
Thus if there were any problems then the light would be on.
Then it dosnt pass

• If your readyness tests are not complete and your light is off, then they will send you away and tell you to drive your truck for a few days and then come back. Hopefully then the readyness tests will be done

You can expodite the process by driving in certian patterns for different tests.
The pattern that I have found that works the best to complete the most tests, is

• Start your truck and let it warm up completely,
• then drive the truck at a steady speed at 40 to 50 mph for 5 miles
• coast down to 30 then back up to 50
• then coast down to 30
• When its convenient stop and let the truck idle for two minutes,
• Then turn it off for at least 5 seconds. thats it.

Where I live there is traffic and it is very difficult to find a time or place to drive it at these speeds for that far.So I just follow it the best I can.
I use this dirve pattern all the time and 90% of the time It will run the tests it needs to pass.
If you havent unhooked your battery or reset your computer recently, and your check engine light is not on then you dont have to worry about any of this information, your car should pass emissions test.

what is happening is your spider gears and side axle gears are probably going out... it might also be the ring and pinion... just happened to my 2000 S10 and turns out spider gears were toasted... have a mechanic check out your differential. you pop the clutch alot?