EVAP testing

[Crusty]

I would like to see the ability to turn on and off, BOTH the purge solonoid AND the vent solonoid, independantly and together.
My Tech-II has the ability to turn them on/off but doesn't seem to allow manual control of both at the same time. It does however allow "system seal" which closes both but we can't then release one or the other for full manual control.
I have only seen the selection for the purge solonoid on my new Solus-Pro. Some of the diagnostic trees for code sets tell you to turn on the vent solonoid manually. (Why on earth would we want to follow the correct diagnostic procedures that I've seen work 99% of the time) (99% is better than 50%)
Tech-II can do it. OTC had the selection in the tool only it didn't bloody well work. 3 different OTC tools with 3 differrent versions of software, all no good (windows CE O/S). We would have chased down wiring or a PCM if I hadn't double checked and found that the solonoid wouldn't respond to the command through the Tech-II. There was in fact no signal from the PCM with the OTC tool.
Vent sol on/off. Purge sol on/off. System seal on/off. They appear to be pretty well universal in all GM's for the last 6 or 7 years.
Can Snap-On give us BETTER control than the OE tool?

[Joe Rappa]

It is unlikely that Snap-on will ever control a PCM better than the manufacturer tool, simply because the tests are a function of PCM control and not scanner control. That is, if the PCM is not capable of running the test then there is no way for the scanner to command it.
The purge/seal test for GMs that you're talking about has been talked about quite a bit here, and requested by many Technicians. Snap-on has been REALLY good lately about adding requested finctional tests to the latest updates. I'd bet we'll see that test added soon.
As for closing vent valves to seal the system, there are quite a few cars that Snap-on doesn work on. More often than not the test is there in my experience. When it isn't, like on the '97 Chevy 1500 I was recently working on, I just use Gobal OBDII Service Mode 8 to close it.
So, to address your first request...I'd agree with you. It would be great to have total control over both the purge and vent valves at the same time, but other than the GM purge/seal test, I'd don't think we'll ever see it.

Joe

[Crusty]

Evap

Since the start of OBD-II (around 1994/95) most generic scan tools and their ability to properly interface with the PCM has been a like shooting craps. As a result I've found better ability to repair the vehicle PROPERLY by staying with the OE emulation within each scanner and following the manufacturers diagnostic trees and flow charts. As a result I don't have much experience with the generic "modes". This is where the scan tool manufacturer "advertised" that their tool would work and do "A-B-C" but RARELY have they delivered what we were intentionally led to believe.
Hopefully OBD-III that I understand is in the pipes will standardize things even more than OBD-II did (which is good as far as it has gone). This industry as a whole has a long way to go in the realm of standardization. If you buy a light switch for your front hall, you can get a $0.99 switch or a $3.25 switch. BOTH WILL FUNCTION PROPERLY. One will just outlast the other.
Some manufacturers just pay lip service to the spirit and intent of OBD-II and just barely comply. IMHO the imports are far worse than the Big-3.
Ya, if the PCM isn't capable the scanner isn't going to do it whether it is OE or not.
An example of the individual control over the vent/purge is a 2004 Pontiac Gr/Prix with a 3.8. I havn't had a chance to check the new Sol-Pro on this vehicle yet but if the OE can turn them on/off separately, can the aftermarket scanner do the same without exiting the first one you command?
This would be a case of the scan tool manufacturer working with the capability of the vehicle PCM and going one better than the OE tool.
I've usually only seen EVAP system code sets in the spring and fall as summer temps are too high and winter temps too cold and are outside the self-test parameters. If I see any EVAP issues summer/winter they are usually very easy to identify with or without a scanner (all you would need is a code reader for $49.95 not a scanner that costs THOUSANDS)