Check the map port, see if it is plugged up..... I don't recall if there is a vacuum line between the manifold, and the sensor, or if the sensor plugs directly into the manifold. But, it appears that the map is seeing one extreme or the other there. (given that it won't run below 1K RPM, I suspect the PCM thinks there is pretty much zero manifold vacuum, and is just dumping gas....)

 

Haha! As luck would have it - I actually have a cheap bore scope coming tomorrow or Friday.
I lent mine out to a coworker a few years ago and they quit and never got it back to me. There's been a few times it would've been nice to have one again and had actually thought about looking down the intake/inspecting the cylinders since it's been dumping so much gas...

The MAP bolts/screws straight to the intake manifold.
I don't recall seeing any obstruction when I swapped the sensors out but that doesn't mean there isn't something blocking things out of the line of sight in there...

 

Ok, so can you simulate vacuum while running and see if return value changes, ie use a vac pump? Also hook vac gauge to MAP line and see Hg and if it changes with throttle?

 

Should be able to test the map key on, engine off, with it unbolted from the intake. (vacuum pump is nice, but, just a piece of hose, and sucking on it should show some change.)

 

I was typing as you were typing. I see now there's no vac line to sensor. Looked at pics on RA.

I'd almost be tempted to machine an adapter that bolts to sensor with nipple for vac pump....but you'd need machine tools

 

Was thinking about what/how the MAP could be blocked and was remembering that the one I removed looked different than the one I installed....
The one I removed had holes in the sensor area like this:


The one I took out didn't have any holes on that face and it was also a bronze color...
I'm wondering if somehow-someway this face with holes we see in the image had gotten sucked into the intake and is creating a blockage in the MAP port? We'll have to see tomorrow. I'm already settled and wont go back out to the shop tonight. Haha

 

Hmm, alrighty. Another test for tomorrow - I'll see what I can do about applying vacuum to the sensor in some way and watch for changes on the return signal line voltage.
Also using the new bore scope to check for obstructions, of course! Haha

 

I wonder if you could literally use a vaccum.....like "Hoover didn't invent the vacuum but he sure sucked as a president".....perhaps the only thing I remember from 9th grade history

Milwaukee sells an "Air Tip" attachment kit for nearly any vac/shop vac. Reduces hose to much smaller hose size. I just used it to suck broken plastic out of an Exploder shifter . Several hose sizes are provided

 

Oh! Very interesting!
I just wiped the sensors clean and sealed my lips around the gasket...

Based on how hard I sucked and blew on the MAP sensors with no result I'm guessing the Vacuum wouldn't have helped too much in this situation. Haha!

Neither of them had any sort of fluctuation in voltage on the return signal. I accidentally touched the sensor surface on my original MAP and noticed something out of the corner of my eye on the multimeter - figured I'd nothing to lose so lightly touched the face again and with little pressure could get it to read up to 5V. Decided to try to do the same to the brand new one - nothing.

Next - I checked the intake with the borescope - couldn't necessarily see any sort of blockages...?

Finally, I installed each sensor and started the truck.

Old sensor:
Key on - not running: .7V
Cranking: Would jump up higher but seemed to average around 1V
"Idling" (me giving gas to keep it at around 1K RPM: 1.1-1.3V
Giving it throttle up to about 2.5K RPM: Voltage never got above 1.5

New Sensor:
All conditions: 1.1V
There was a couple times in cranking when I'd see it sort of jump

For fun I kept the new sensor bolted up and plugged in the old sensor. Fired the truck up and put a board I cut to the perfect length to keep it at about 1k RPM - a little lower. It was running a little rough and then I barely, ever so slightly touched the surface of the MAP sensor and it chugged and died. I wanted to see if I could get to run any better or worse by manipulating the MAP sensor. Figured no real harm done since neither seem to be functioning correctly but one would respond in some sort of way. haha

Looks like I've got to order ANOTHER MAP sensor. Pretty disappointing that the brand new one seems to be junk out of the box. NAPA sensor. Always heard they had better electronics and that's why they ran a little more expensive than other parts stores...
Any recommendations for my next order? Haha

 

Yeah, I think you have another bad sensor.... Certainly not unheard of..... Part quality has declined dramatically in the aftermarket over the last several years.... But, it isn't new either. I used to buy three thermostats at a time for my Scirrocco.... that way I would be reasonably sure of getting one that worked.....