I just got my AutoEnginuity tool yesterday, and hooked it up to find the snapshots around the SES light I set last week (something about boost). I set the code after removing the wire that was holding the wastegate shut. It's now working on the vacuum system, but I'm getting a LOT of black smoke under load. Back to the code... It seems it was reading a barometric pressure of 11 psi and a MAP of 15 at 2000 rpm under 66% load and 17 mph.

When I look at the live readings idling in the driveway, it shows 11 psi for the baro pressure and 14 psi for MAP. I'm thinking they should be reading the same at idle, and it should be somewhere near 15 for both at sea level, so I'm thinking my BARO sensor might be bad. ...or at least reading low for some reason. The ECM thinks I'm getting 3-4 lbs of boost more than I'm really getting, so black smoke ensues?

Does that sound right?

This AutoEnginuity is really cool! ...and the support was great yesterday. I didn't get the tool until Friday night, and they have a manual activation process for the enhancements that only works during business hours. I e-mailed support and they hooked me up yesterday so I wouldn't have to wait until Monday. I suspect the OBD-2 tool performs the same functions for less money, but I'm happy with my AutoEnginuity so far. The GUI is very nice and it's easy to use.

BARO readings should be 29.0-30.0 what ever your local weather center says it is outside.
MAP should show hight at idle and low under load like a vacuum gauge would show if you had one to hook up.
I have seen some scanners show the opposite vaccum reading when running. The big thing is to watch for the change from no load to load.
Also some GM's run two sensors 1 for map and 1 for baro.
Others just 1, it takes a baro reading with key on eng off then switches to map after it's started.

I'll have to check the units on the thing. I think I got confused between psi for pressure and the stoichiometric combustion mixture normal.

Our barometric pressure from the weather is corrected to sea level, so it's not much use. We run about 650 Torr typically; I can call the hospital blood gas lab to find out exactly. I'll work on the units and conversions to see where this should be. I was under the impression that the baro sensor was on the firewall. I know where the MAP sensor is. Time to start looking in the shop manuals.

If were talking about the 99 in your sig, then you should have only the boost pressure sensor(MAP) on the intake. The one sensor gives you both atmospheric and intake pressure readings.

Yup; it's the truck in my sig. And I got to thinking about psi and Torr and weather barometer. I looked it up on the Internet (great thing that Internet). 1 atmosphere at sea level = 14.7 psi, 760 Torr, or some 30 inches of mercury (which is what the weatherman uses). So it seems my barometric reading of 11 isn't too bad considering we have a storm, so our baro is likely about 630 mmHg or 12-ish psi. But at idle, it seems boost (MAP) and baro should be pretty close to the same?

Does the sensor use the same probe point in the manifold or is there something on the top to measure barometric pressure? Does it take the baro reading with the engine off and then switch to boost once the engine starts?

After driving to church this morning, there seems to be something wrong with more than the WG actuator. The WG solenoid seems to need to be changed or troubleshot. ...or just shot.

The Heath spring is looking better all the time.

I finally found the right section in my shop manuals. ...sure would have been nice if they'd indexed the wastegate system.

The engines with EGR have a separate BARO sensor because it's part of the EGR system. The F engines check BARO at key on, engine off, using the MAP sensor. The manual gives test readings in kg/pascal or something like that. I'll need to change my software to metric to read that. ...next time.

The test for the wastegate actuator is to apply 5 inches vacuum and see if it holds. Mine won't even pump up at all.

I have a faulty wastegate actuator, and it seems to me that my wastegate solenoid is intermittent, and the MAP sensor acts funny.

This is why most folks trash this system and put a spring on the wastegate. I had wanted to keep this system for the altitude changes I drive through, but it looks like I need to key off and restart the truck any time I want to change the BARO reading. Blech! When I start the truck at home (4500 ft) then drive to 9000 feet, I actually get less boost, because the stupid thing has a higher BARO reading than it should and drives boost off the difference betweent the BARO and the BOOST readings.

Methinks I'll get a Heath spring in the spring after I get gauges. It seems it's better suited for altitude changes than the factory system. We'll see if it passes the visual emissions check next fall.

They do the initial altitude check at initial key on engine off, bu they do re-sample often when conditions permit. On a gasser every time you give it more than 85% throttle they re-check the barometer. I believe the 96+ OBD2's re-check when you let off the throttle, or are at a steady easy cruise. They do re-sample though.

They do the initial altitude check at initial key on engine off, bu they do re-sample often when conditions permit. On a gasser every time you give it more than 85% throttle they re-check the barometer. I believe the 96+ OBD2's re-check when you let off the throttle, or are at a steady easy cruise. They do re-sample though.

That makes me feel a little better. I'll watch for it next time I head for the hills.