hi, on a working mans payroll, a standard obd2 code reader, just reads the current engine running, indicated rpm's, correct? how much do i need to spend to get the programmed rpm's, and possiablly be able to change it?

also on my truck the charcoal canister for the fuel vapor, (located rear of truck, behind fuel tank, in front of slightly the spare tire, do these ever go bad? my mounting brackets are completly rusted, so iam trying to come up with a new mount/holder for the canister. does anyone know if thier is a aftermarket replacement, or do i have to use oem. mine looks like a big pvc tube that i had on my trial bike to hold tools, anyway its long cylindrical tube. in later years did this get removed, replaced with different size? can i use one off a newer truck? any help greatly apreicated

 

First question is why change it?
If it is out of spec the cause needs to be found and corrected.
Idle is part of a total design, not an individual parameter.
Some 101 on it:
A. Cold start high idle control.
B. Ability to control idle on a continuous basis.
C. Engine coolant temperature is involved.
D. Crank sensor feeds back engine RPM to compare to a programmed table for corrections by the Intake Air Controller.
All these actions are monitored and have code assigned.
Change any and affect others.
The throttle body has a stop that keeps the throttle plate open a small amount for a purpose that involve control range for the IAC variations controlling Idle to within +/- 50 rpm of about 750.
If your above or below on a fully heated engine a fault is present.
Cold starts should be at some point above hot Idle until the engine comes into closed Loop and fully heated. This depends on thermostat, cylinder head temperature and Ox sensor actions vs time.
The EVAP system is tied into this actions and can be affecting.
A vacuum leak fault can be affecting.
It's not a simple change because it's the result of many other actions.

 

I think the only way the charcoal canister can go bad is when it gets filled with road dust. The canister is basically open to air, but not directly. There is a long hose (1/2"?) several feet long and it ends in a hollow plastic box. It is highly unlikely road dust can pass through the hose and fill the canister.

If somehow the hose gets damaged, dust may enter the canister easily. In that case, you can use any canister from any car but with the same vent valve.