How Long for Computer to Reset and hard warm starts

[bobterisch]

Happy Holidays Everyone,
Have a 96 S-10 Blazer 4.3L. It had a dead battery recently before inspection was due. Drove it ~ 60 miles and mechanic said the computer was not ready. Drove it another 80 miles and mechaic says the computer is still not ready. How many miles does it have to go before the compter will be ready?
also the Blazer runs fine and starts right up when cold, once it is warmed up it is hard to start. Pumping the gas pedal seemd to help.
Thanks for your replies,
Bob

[danielsatur]

Do a Google on ''Blazer drive cycle''
Try to simulate the drive cycle, and check I/O monitor with an AutoScanner.
''inc'' status is incomplete drive cycle.

Drive cycle = MPH city driving + MPH highway driving!

[bobterisch]

Thanks Dan.

[old_master]

Here is the GM drive cycle: http://www.obdii.com/drivecycle.html

Find out which monitor is incomplete and follow the steps to complete it. You don't have to do all 8 steps, just the necessary ones to satisfy the readiness mode.

[bobterisch]

Thank you guys

[RahX]

Your best bet is to drive it for 15 mins around town, normal driving. Shut it off count to 10 and restart it and do it again. Repeat 3-4 times and then do some highway driving, 15-20 mins a couple times and you should be good.

[bobterisch]

Happy new year Everyone,
I followed the drive cycle instructions with coasting down to 20mph. Did the around town thing. did the cold start idle. The truck has been driven over 120 miles but there are still 3 monitors not ready.
catalyst
O2 heater
evap
Any advice would be appricited!
Bob

[old_master]

To complete those monitors, the entire drive cycle must be completed. Each monitor "watches" for a specific order of events each time the vehicle is started and driven, (drive trip). During the drive cycle, when the first requirement of a test is met, the monitor begins to run its test. If ALL of the necessary requirements are met in the proper order, the monitor will complete its test. If all requirements are not met during the drive cycle, the test will not be completed. This holds true for each of the monitors. During a drive trip, some monitors will constantly try to run their test, others try once per drive trip. Each step of the drive cycle must be performed EXACTLY as outlined for every monitor to run its test and complete it. I've had customers drive for MONTHS and not complete all of the monitors. You don't have to perform all 8 steps consecutively, or even in the same drive trip. Each step outlines what monitor will run if the instructions are followed.


A drive trip is when the vehicle is started and brought up to 160 degrees Fahrenheit and at least 40 degrees Fahrenheit above its original starting temperature. It must then meet specific enable criteria for a diagnostic monitor to start, run and show a pass or fail.

A drive cycle is the same as above, but, all of the diagnostic monitors must complete and show a pass or fail result. The OBD II drive cycle is the complete test running without interruption.

[bobterisch]

Thanks for your help. Will try again

[bobterisch]

Old Master,
One more question please. How important are the times in the steps that have 3 minute and 5 minute drive times @ 55 with a coast down to 20mph?

[old_master]

If you want the monitor to run, the instructions must be followed exactly. The parameters are set in the PCM, they are digital, you either do it exactly as instructed, or the monitor doesn't complete its test. So, to answer your question... It's not only very important, it's mandatory.

[bobterisch]

Master,
6 more drive cycles completed exactly. Still no catalyst, evap and O2 heater monotors set. Afriend mentioned to me that these could possibly have something to do with the very cols weather we are having here in NY. Do you know if there is a air or engine temp minimum requirement.
Thanks!

[old_master]

In the GM dealer issue shop manual it states that the fuel level must be between 15% and 85% for the evap monitor to run. Here's another drive cycle with a little more detail:

1.Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 122°F (50°C) and within 11°F (6°C) of the ambient air temperature at startup.
Do not leave the key in 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 55mph (88km/hr) 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 55mph (88km/hr) 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 20 mph (32km/hr). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.

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

7.Hold Steady Speed. Hold a steady speed of 55mph (88km/hr) 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.