The last part of step 1 says "Do not leave the key in prior to the cold start or the heated oxygen sensor diagnostic may not run." I would start the truck and during the 2 1/2 minute idle read and write down the live stream data from the scanner. All the data, what else you got to do with that time? I would make sure that the Engine Coolant Temperature is not over 11 degrees of the Intake Air Temperature (IAT). When my truck sits overnight those temp readings are the same at initial start up.

 

You know I don't understand why the pcm don't remember each step and when they all are done correct complete the evap im.I don't want to sit on the freeway for 3 1/2 hours so the engine can cool to within 11 degrees of the outside temp.Then do the warm up 2 1/2 min with every thing on why don't it log in that step as complete from my home then when I drive to the freeway start the 3 minute 55 mph then coast to 20 mph by the way would using the four ways cancel the attempt, then accelerate to 55 for 5 minutes then coast to 20 mph flashers on then show the evap as complete or throw a code if there is a problem with anything.Or does it really have to be done 123 warm up every thing on.Turn every thing off accelerate to 55 mph half throttle coast to 20 mph again accelerate to 55 mph 5 minutes then coast to 20 mph then accelerate the test is done.But I know even if it should work that way it don't because I have done every thing from warm up every thing on 2 1/2 minutes turn every thing off drive to freeway accelerate to 55 mph 3 minutes don't touch the brake or down shift coast to 20 mph accelerate again to 55 mph 5 minutes coast to 20 mph then drive away test should be complete.But that don't work have tried many times with no success so it has to be 123 or nothing.Or pay gm to hook it up to there computer for 5 minutes and have them set it as complete and charge me what they feel like at that time.

 

You know I don't understand why the pcm don't remember each step and when they all are done correct complete the evap im. I stopped at the Seaview Chevrolet Dealership today and talked with a shop Stewart.He said the gm test isn't that difficult and anyone should be able to reset the evap monitor in a hour or two.As long as there isn't any codes.I told him that I have been trying for a while now,and he said the four ways and blinkers can be used just don't touch the brake that will reset the test to the start if you do that during the test.He also said that having the code reader plugged in may be interfering with the test he said complete the test including some city driving as well then when your done trying turn off the car and then and only then hook up the code reader because I told him it was always hooked up during the different test,s and his thought was it might be interfering with the test itself.I don't know for sure bur the rest of the supported im,s cleared right away after resetting the code from pulling the vent valve and the little air intake right after the MAF to see if as it was noticed right away so if there was something wrong in the system you would think it would set a code quickly.As does pulling the plug on a sensor.

 

Some systems are constantly monitored, others are only monitored under a specific set of circumstances. The drive cycle duplicates those circumstances. I can't quote my 2000 factory service manual for your 2003 because it could send you in the wrong direction. Used service manual sets sell for under $150. For someone wanting to learn to fix everything himself it's a necessary tool. Respectfully, I think you have gotten as far as you can go without it.

 

I found the vent valve to be faulty even though the OBD didn't set a code for it. Testing is how I found out, and seen another test using vacuum to test the purge valve. And again it was faulty and again the OBD hasn't set any code to let me know.But maybe that's why the evap system isn't responding to drive cycles or letting me know the vent and purge valves are faulty after all my car just hit 100.000 a week ago if the valves are original then they have been working for quite a wile.And if the evap system won't work until every thing is up to par so it can complete its testing then after replacing the purge valve if it's the last broken thing in the evap system then just maybe it will resume its self testing.And then allow me to do a drive cycle to reset the monitor that as of yet 25-30 times and still not recognizing the drive cycle.Is that even possible that if for a reason like I pulled the battery and the alternator while replacing the intake gaskets.And either the evap had a code that I didn't know about could it have stalled out the evap system until every thing was back to working so the evap could resume it,s test cycle.What,s so weird is that each time I find a bad part through testing then unplug it to go to the parts store the OBD notices rite away usually I cant even get out of the drive way with out setting the mil and a code now if it can do that why can't it catch a bad purge valve and a bad vent valve.And set a code both valves activated to power but both wouldn't hold vacuum that means they were leaking even when the vent was energized and the purge as well.Rusty or Captain will one of you answer me on this it,s very confusing.

 

Like I said I thought the OBD would catch each of those valves before I pulled and replaced them and I am still facing the same issue the evap don't recognize any drive cycles even though I believe I am following the correct one for gm.It don't recognize anything even a faulty valve.Until you unplug it to test it or set it back were it belongs just long enough to go to the parts store. don't hook up the harness or line from the charcoal canister And the purge or the vent valve will set a code but not if it is faulty now how does that work Captain is there something I am missing would love to here it. I am just about at my end of attempts to have it run complete.My Last try would be go to my parents garage put my pressure cap on I made and add a little air hopefully enough to trick the pressure valve into thinking there is gas fume pressure building in it as last ditch response to see if I can trick the pressure sensor into activating I don't know if it is wise but like I said its the last of my bag of tricks it may fail or it may work either way I wont add much compressed air with hopes not to damage anything just trick it into working.I will disconnect the tank line to the canister and plug it so if the pressure sensor sends a signal to the OBDII then and just maybe this system can be tricked into working again. Ok Captain am I foolish for even trying this.One last question doesn't the pressure start off the hole emission process when pressure positive like in summer or negative like when the car was hot then was parked in the shade. Isn't that were it all begins.The pressure sensor tells the OBDII to open the purge and close the vent for a short time during closed loop something I can check on the data stream but every time I have checked it has been closed loop perfect time for the pressure sensor to tell the OBDII to open the purge and close the vent valve.Then the OBDII watches the pressure for a drop to set a code if there is a leak.Come on Captain help me out here.

 

Added compressed air to my gas tank to see if it was leaking.After applying a small amount of air removed the nozzle and the air pressure hit me in the face guess that still don't help if there is a small vacuum leak guess I will just have to smoke it to find out if there are any leaks.One question I have current data on my code reader what would the reading be for the pressure sensor in the tank or would current data show that at all.

 

just cancel this if you would Rusty.

 

Like I said this scanner has a feature under On Board Systems its under menu as special test and just the other day at a stop I pushed the button and it said communicating with the vehicle and then it made the engine stumble at the time I didn't realize it was turning on the purge valve even though it normally don't turn on until the engine is warm and moving fast enough so it can burn the gasses from the canister with out stalling the mortar.So if this is able to turn on the purge valve then why don't the evap continue with the rest of its test,s and complete the evap system or set a code for a leak if there is one.Also another test it does is live or recorded data so you can see what is going on in the engine the other day I blew a fuse Eng #1 and one thing i noticed was that the MAF had stopped working it just displayed #26 and didn't change at all with throttle but after replacing the fuse it went back to working normal.So Rusty Nuts my question to you until I get my gm manuals is if the purge is able to be commanded on shouldn't the rest of the evap work as well and set a leak code if it has one.But even if the answer is no I bought a nice 12 volt smoker on EBay some one used a paint sprayer canister and turned it into a quite nice smoke tester so when I get it I am smoking the entire system.

 

Delete this as well Rusty to many words saying the same thing.
theirs more down below just delete all but answer question if you can.