Ok so I bought an alta kit (prosport digital gauges: water temp and boost) a couple weeks ago and installed it the other day. The water temp works great but for some reason the boost gauge reads down in the vacuum range (in hg) at idle the gauge reads about 22 in hg, under WOT it reads about 1.5PSI. With the engine off but the ignition on the gauge shows about 6 in hg

Under WOT:

I have checked and re-checked all the wiring... black is ground, red is constant 12 volts, white and orange control display color... I followed the alta directions 100% and then decided to try the sticky boost gauge install method, i.e. tap in under the FPR, this install went fine. there are no kinks or leaks in the lines anywhere; I even replaced the vacuum line as a precaution. The added "T" is also free of defects. As a test I hooked the sensor up to my air compressor (calm down, less than 20 PSI in the tank!) and the gauge would read about 16psi, so the gague and sensor must work. I know the car is getting boost; I haven’t thrown any codes and there is some serious pull under WOT. Any thoughts why it might be doing this?

 

perhaps a bad gauge? even though the needle moves under boost(in reference to hooking up your air compressor) i wouldnt rule out a bad gauge. go to autozone, buy/rent/borrow a cheapo boost gauge and see what the outcome is.

 

Did you post this in the Alta Q & A forum. Contact Adam. I'm sure he'll help you out.

 

you might have the vacuum line hooked up to a port that does not see full boost pressure. It is a pain but you have to hook it up to the line for the fuel pressure regulator.

 

Looks like a bad gauge to me...

 

Did you ever get this fixed? I'm curious as I seem to be having the same problem after I installed mine this weekend. No codes, engine idle is smooth, I can feel vacuum from the tube if I pull it off the gauge but for some reason it does not read above 0psi aven at WOT.

 

Would be interesting to find out. On my boost gauge, with the ignition on and the engine off, the needle is pointing to zero. If the needle is not zeroed out, something else is amiss. You cannot have a vacuum (or boost) condition if the engine is not running.

 

Is the needle supposed to be at zero when idling? Mine is always at 6'o clock????

 

When the car and ignition is off it will go through its power-down routine and lay at the 6 position. When the ignition is in the on position but the engine off it should read zero.

 

Well as of now my gauge doesn't even work. It does the start up but that's it. Any idea what's wrong now? Im bout to rip it out in a few days.

 

check all your connections. I have had to push in the plug on the sensor wire a couple times. The one on the little black box in the engine bay.

 

I did. I checked all the hoses to see if there are any cracks. I unplugged the map sensor and reinstalled it. Unplugged the cable that goes into the little black box. Unplugged the 2 plugs behind the gauge. Ill try it again later. But even when my car was engine on the needle was at 6 and not 9 like everyone elses. Did I reverse something? Or got a bad gauge?

 

Please keep us posted. I was planning to install these..
Thanks Axo

 

When I had the vgs mod done. For some reason the mod takes away any of the boost that the gauge is registering. Mine wouldn't go past 3 psi. I reverted back to normal vacuum and it works great..worth trying

 

Not to stray to far from the topic. What exactly is the "boost" that the boost gauge reads?

 

Rrated, I never had the problem of a low boost read with the VGS mod. I just took it off about two weeks ago. Same boost readings either way.

MyMiniGidget, boost is read from a vacuum line (#13 in photo below) that runs from the intake manifold to the fuel pressure regulator (#7 in photo below). It is this line that you tap to get a boost reading, usually done with a 5/32" T fitting and some extra 5/32" hose to run over to the boost gauge.

The VGS mod thread uses the same boost line. You can find more here: https://www.northamericanmotoring.co...?highlight=vgs. It's a long thread, but it provides a good amount of information.