Clearing OBD codes and I/M Monitors (what it all means)

[TerribleTed]

Howdy all. So I recently plugged in my OBD code reader and cleared my codes after some recent cat replacement work and here is what I wish to know (that is if anyone has valid understanding of the internal IM monitors and all)..

I heard that after you clear the codes you have to drive it at elast 100 miles to allow all the IM monitors to pass (or get into the ready state). So far I have driven over 100 miles and I noticed that at around 60 miles of driving all but 1 (im monitor was in a ready state, as aposed to the not ready state it was in).

Now after the 105 miles I have driven it, my OBD code reader shows that the "evap" i/m monito still is not ready.

So I ask this of any that have understanding of the EVAP system...
1. What is the evap system and what parts is it composed of
2. Why is it that after the 100 miles driven since I cleared my codes that its still not in a ready state and still in a not ready state?
3. thats all....


Thanks

[blue02Z]

THE EVAP IS THE MONITORING OF YOUR EVAPORATIVE EMMISION SYSTEM. FOR LEAKS IN THE SYSTEM FOR EXAMPLE YOUR GAS CAP BEING LEFT OFF. THESE CONDITIONS NEED TO BE MET TO RUN FOR A EVAP CODE:


• DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0420, P0430, P0500, P0502, P0503, P0562, P0563, and HO2S DTCs are not set.

• The ignition voltage is between 10 volts and 17 volts.

• The barometric pressure is more than 75 kPa.

• The fuel level is between 15 percent and 85 percent of full capacity.

• The engine coolant temperature is between 4°C (39°F) and 30°C (86°F).

• The intake air temperature is between 4°C (39°F) and 30°C (86°F).

• The start up engine coolant and intake air temperatures are within 9°C (16°F) of each other.

[Cutlass]

Back in the old days, gas tanks were vented to the atmosphere. Apparently those gas fumes are bad for the environment. Now the gas tanks are sealed and the excess fumes are collected and purged into the engine while its running. If the system leaks, a SES light will come on.
It might take several trips/days for the evap tests to run and pass.

[TerribleTed]

Back in the old days, gas tanks were vented to the atmosphere. Apparently those gas fumes are bad for the environment. Now the gas tanks are sealed and the excess fumes are collected and purged into the engine while its running. If the system leaks, a SES light will come on.
It might take several trips/days for the evap tests to run and pass.

...
so no SES lite on a thing,,still has not cleared the evap monitor,,so I filled the tank most of the way,,,and after some fo the date in the prvious replies,,I see that once it cools down in my area,,,it should alow the IM to pass or clear,,its been heck hot around here in Sacramento California area,,,and its not from polotical heat,,ha ha,,its just around 100 the past few days,,,and this is the most likely cause of the IM not clearing,,

thanks all for the data,,,

Now its on to drilling out some exhaust manifold busted studs,,,drill baby drill,,,,

have a great weak end all,,,