I just installed my Stri DSD-SLM II boost gauge, I used my factory installed boost line (the one that the MR Gauge pack uses). When i turn the ignition on, and do not start the car the gauge reads around -1 to -2 inHg. I cant figure out why because the car is off. When the car is on and idling it reads -20. Anyone know why?? Thanks in advance.

 

Your gauge sounds like it is off. My Stewart Warner did this and had to send it back in order to get a new one.

 

I seldom even have -20 in hg at idle. It is usually right at -15 in hg. I'm using an Autometer boost gauge. Definitely sounds like yours is off.

 

Had the same problem with an Autometer gauge. It wound up being that it was because i installed an LED bulb that was a milimeter too long and it wound up hitting the back of the needle inside.

 

So I called Auto Tech Interiors, since that was the number that is listed on the Stri website. They didn't answer, and have yet to return my call. Tonight I will be sending them an e-mail.

But I did some searching, like I should have done before and read that my vacuum is normal, especially for my altitude. However, I am still curious as to why my gauge still reads a negative mmHg when the engine is with ignition on.

The only thing I can think would cause this is some component causing some sort of vacuum. Hopefully someone will give some insight!

 

It shouldn't read any negative when the engine isn't running. The idle for me fluctuates about 5 in hg, so your vacuum may be normal. I just don't trust a gauge that can't reset and zero itself properly when turned off.