Right. Heading out to check that hypothesis now!

 

did you try backing the sensor out a bit?

 

Alright, if this is what you mean, I just tried that. Still no luck.

 

Hmmmmm....

 

This is odd because you were getting 20hg at the gauge like you should, something is not right/tight/pinched.

 

can u make a poopy diagram of how you have the hoses setup including anything you have like t's etc.?

 

It gets weirder. I had 20hg a few moments ago *after* removing the MAP sensor at the tap. Instead of typing it/explaining, I took some videos and they're going up now. In just a few minutes, you can hear me stumbling over my words in frustration.

The hose setup is really simple - when I'm testing the pressure, it's just the nipple to the gauge. I've tried the 3/16" and 5/32" tubing, no bends or kinks, directly to the gauge.

I can't replicate the 20hg fluke - I wish I could, but it took manipulation to do so, and only appeared after causing a vacuum leak at the tap/MAP sensor junction.

 

the issue seems to be at the tap. what about if you all but remove the sensor from the tap. so it barely seals?

 

Here we go. You'll see the answer to that last one in these:

1) http://www.youtube.com/watch?v=y8nk-ZLAumI

2) http://www.youtube.com/watch?v=QuwzBGRhFuk

I'm 99.9% certain that the tap has a failure, and it seems like it's at the tap nipple.

 

U sure the screw in the tap isnt too deep?

 

saw the vids stumped really, i would have to get in there myself to see what was up.

Blow test every passage.

Tap the gauge make sure is not faulty, test it on another car or with the line that goes to the brake booster.

 

Yep, it doesn't go into the body. It's a tiny/short little screw that doesn't even go past the outer wall.

There are no obstructions in the boost tap. I'll grab it off the car and take some pics.

 

If you blow on one end while the map is inserted does it come out the other?


You def. have a vacuum source, there is a pinch/leak that is tight/small enough to prevent vacuum from completely getting to the gauge.

Gauge could be pooped also. be sure to test it on something else, or the brake booster line if need be

 

It could be worse - I could have no vac at the intake manifold!

I might try using that screw hole and blocking off the tap nipple. Of course, to do that, I'd need to spin it around (since someone was sleeping the day they designed that), but it's worth a shot, I'm sure.

Just hauled out the other gauge - same readings.

Here are the pictures, as promised:

 

If u had no vacuum the car wouldnt be running ;-),


This is odd...

Try using a line to the vacuum pump -> gauge and see if you get a reading

Could be the map sensor pinches the outlet port of the tap?

 

Exactly - hence, it could always be worse!

 

Leaving work, let me know!

 

Alrighty - got caught up there, sorry for that.

Both gauges are A-ok. Tested on the brake booster, got a full 30hg (I'm sure it's more, but the gauges maxed out). One gauge is more accurate than the other, so I'll end up using that one. Long story short, no developments.

Here's a new video - http://www.youtube.com/watch?v=27rX6dHI9uw

You can tell I'm starting to lose my mind with some of these ideas. I basically made sure that there was no leaking between the boost tap, the MAP sensor, and the nipple out to the gauge by wrapping the crap out of all of it. No leaks, but still no vacuum pressure. That really leaves the connection between the manifold and the boost tap, so I'll investigate that now - not sure how to go about testing that one.

 

Removed all the tape from the last experiment. I need to find another boost tap ASAP. That's the only way to test the last piece in the puzzle. That is literally the only explanation left.

1) Gauges are good. (Have 2, tested both on brake booster).
2) Good vacuum when MAP sensor unplugged - car stalls/runs hard.
3) Intermittent full vac reading (around 18Hg) on the boost tap - no rhyme or reason. Turn car off, back on (no changes) - no vac reading again.
4) Good vacuum when MAP sensor unplugged from boost tap.
5) Only running single line (tried several line types - silicone, fuel line, vac line) directly from boost tap to gauge.
6) Tried O-rings on boost tap and MAP sensor to eliminate possibility of long necks blocking ports.
7) Sealed section from manifold to tap with gasket, no change.

There's nothing else it could be, assuming we're using deductive reasoning. It has to be the boost tap either leaking or getting blocked somehow internally.

PMed Way last night, but no answer. Guess I can call Forge directly - need something like yesterday since this is my daily driver.

 

My guess is the tap, see if you can measure the depth of the map sensor fitting and compare that w a piece of paper to the tap, see if it goes further than the tap port to see if it is blocking it.

know what i mean?

 

Alright, I just cut a gasket for the MAP sensor to sit on when it's installed in the tap. This way, the tip of the sensor is nowhere close to the boost tap nipple. Here's what it looks like (yet another crude drawing).



No change. I'm going to go crazy over this. I can almost guarantee it.

 

Damn, this is nuts.

 

It's not normal, that's for sure.

The only thing I can think is that somehow it was machined incorrectly, but it's just 4 holes in a block of aluminum - not rocket science.

 

but if you go back to stock you have no issues. The car wouldnt run without vacuum. there is just a problem somewhere in the routing you are adding.

 

Yep, I should think it would die without vacuum. I'd gladly just put it back together and call it a day, but that solenoid runs off the tap. Without that working, my BPV doesn't work, and I believe I could wave goodbye to the turbo.

There can't be an issue with the routing, as it's not being routed anywhere.

I can literally take off the hose from the tap nipple and have nothing connected, and there's only a slight suction. Hell, the car doesn't even notice and keeps humming along. Isn't that some crap?

I wish I could say that I was the stupid one, but I really can't even do that. At times I can be quite dim, but this is just idiot-proof.