Pulse Width Modulation, not Pulse Width Moderation

https://en.wikipedia.org/wiki/Pulse-width_modulation

 

[QUOTE=Lesmyer;660600]Pulse Width Modulation, not Pulse Width Moderation

https://en.wikipedia.org/wiki/Pulse-width_modulation

 

When the ignition is in the run position, the purge and vent solenoids are supplied constant battery voltage, and they remain in their default positions. The vent solenoid valve is normally open. To close it, the PCM applies a constant ground and it slams shut. The purge solenoid is normally closed, BUT, the EVAP flow needs to be introduced to the engine gradually, so the PCM applies a pulsed ground, (PWM). It is viewed on a scan tool as a percentage of time, called a "duty cycle". With a 0% duty cycle, the valve is closed. With a 10% duty cycle, (valve is open 10% of the time) it clicks rapidly and the flow is low. With a 100% duty cycle, it clicks once, the valve fully opens, and the flow is high.


With regards to your 9 volt battery: Both of the solenoids require very low amperage to operate. The 9 volt battery can only supply a low amperage, but it's enough to operate the solenoids. If the voltage drops to ~5 volts, the available amperage would not be enough to operate the solenoids. Voltage is important, but available amperage is more important.

 

I tried both valves with the 9 volt and it would only work on the purge valve the vent valve took 12 volts to make it activate and after supplying 5hg of vacuum id didn't hold at all .I bought a new one and jumped it and added vacuum to see if it leaked at all it didn't held for as long as I wanted to hold it there.You know Captain one thing I don't understand is why the bad vent valve didn't set a code in the two months since I did the intake gaskets and the evap wouldn't complete its test cycle.I found another site for getting your car ready for a drive clean emission test It starts out like this
1 Start out with either 1/4 tank of gas or 3/4 of a tank just like you said.
2 Let the car sit over night 8 hours or more.
3 Start the engine let it warm up to normal operating temp.
4 Drive the vehicle for a minim of 10 minutes at high way speed 55-68
5 Drive the vehicle at least 20 minutes in stop and go traffic with at least 4 idle periods engine running while at a stop.
6 Don't turn the vehicle off for anything during any of the above test until the very end.Hope this gets it I am getting tired of a system with no codes or a mil light should be im complete.But isn't.
7 Car should remain im ready unless the check engine light comes on.
8 What do you think of this one you surly wont be threatened like the gm drive cycle slowing to 20 mph twice believe me the people out here don't like you slowing them down.I need my own speed way for this kind of driving issues.

 

Here, this tells you what is being tested at each step of the drive cycle. Note that Purge appears in 6 of the 8 steps. Better do them all.

I imagine a problem with anything within a step could prevent the entire step from completing.

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General Motors (specific) OBD II Drive Cycle

 

This is what I have been doing now for 20 times or more that's what I say when I say it pisses the other drivers on the road off to no end because the drive cycle says to turn every thing off it then has after 3 min and 5 min you coast to 20 mpg this is where they get really mad the test don't say nothing about if you can use four way's to alert the other drivers but it does say don't touch the brake and the four way is flashing the higher element so I am not sure if it's allowed in the drive cycle but never the less I have done 20 of these drive cycle then tested with a Actron 9680 code reader and even hooked it up before the drive cycle and it has a drive test cycle on it where any uncompleted im's will blink while your performing the drive cycle they all reset except the evap through out the test and after completion it remains blinking and no check engine light or codes to let you know why its not completing after many perfect drive cycles.So again why do you think it allowed the evap or the pcm not to set a code when the old vent valve was on my car with a slow leak that I showed when hooked up to battery and applying small amount of vacuum and watching it leak down even energized.

 

Yes Captain again I do listen to what you say and that's what is bothering me about failing the drive cycle 20 or more times. Ok it starts the car turn everything on 2 1/2 minutes then 1/2 throttle to 55 for three minutes,I don't live close so after the warm up I need to drive normally to the freeway but the test doesn't say that like you said to a T the drive to the freeway after the warm up is where its more then likely messing up.I need a location where I can do the start and every step after that no exceptions like driving to the freeway seems to do. There isn't any other answer for why after 20 or more drive cycles I still have a incomplete evap system.No Mil or a code just a incomplete evap im.

 

You know Captain If its only the drive to the freeway that is messing up my attempts then I should be able to resolve that real easy the new Actron 9680 that I bought instead of the $1,200.00 tire gauge.Has Data Stream real time so I could set on the freeway until the temp lowers to GM says 122 F. This wouldn't take that long waiting on the freeway then complete the drive cycle as I have so many times before.But after the 2 1/2 warm up accelerate to 55 mph no drive in between after 3 min coast to 20 mph then accelerate to 55-60 for 5 min coast to 20 mph then accelerate your done gm drive cycle done to a T.Now that's the last attempt at passing this thing. I disconnected the vent valve started the car long enough for it to set two codes vent valve failure and same pending.Drove to the freeway like so many other times did the 3 min part the coasted you get the pitcher still know evap complete instead just the opposite after 10 miles north then 10 more coming back south still a failure.Going to have to set along side the freeway for a hour hope no state patrols stop to help out but after a cool down of a hour should be enough 122 F or lower then maybe just maybe this can all be behind me but I tell you I would never had believed this gm Drive Cycle could be so incredibly picky.I hope this is the magic one I sure do.OH and the Actron has a drive cycle monitor setting that allows you to monitor the evap monitor and all the others supported so if I reset the dtc codes all the monitors will begin to flash when you put it in drive cycle mode and by the time you leave the freeway all are reset usually except the evap.But this time all should be set complete.

 

Reread the second half of step 1. The underlined part. The ambient (outside) air temperature must be within 11 degrees of the coolant temperature to be classified as a cold start. That means if you let your coolant cool down to 121 degrees, then it must be 110 degrees of hotter outside to qualify as a cold start.

I would find a gas station, rest area, carpool parking lot, truck stop or anything by the highway I could drop my truck off at and let it cool down until later in the evening when traffic is light and come back to perform the drive cycle. How far are you from Waterford, Michigan? I'll give you a ride to drop it off and pick it up if you need one.

 

Thanks Rusty Nuts for the offer but I am in Washington so the ride thing wouldn't work and thank you for the clarification so if it's 50 degrees out then my car needs to be 61 degrees before it would count as a cold start. Is that rite is that how it works.I have no codes and no mil light and I contacted the Emissions people and your allowed one incomplete IM monitor and you can still pass if its not messing with my gas mixture my car just hit 100000 but it has never failed on the test yet I get a good gas treatment drive for about a hour and then go test haven't failed yet and sure don't want to next month when I am due for the test. But can't understand why now it won't complete it has always completed it was just the most stubborn one of all.Since doing my intake gaskets and battery with the alternator it did this.I understand why when you disconnected the battery it resets all the monitors. and the vent valve wasn't holding air when activated so I replaced it but the computer never noticed it was bad until I disconnected it and went to the parts store to get a new one and it through a code rite away but after replacing the valve I erased the code and it never came back.So am I rite on the temp thing now because I could park it on the shoulder of the on ramp and go have lunch by the on ramp and give it enough time to go from 195 down to 61 degrees if its 50 degrees out.That's if I got the temp thing rite at 50 degrees it should cool down in a hour or two and I have a Actron code reader that gives a live data stream so I can tell what the engines exact temp is at any time now with out starting just have to turn the key to on.