Boost gauge reading different than microtech
 

Alright, I hooked up a boost gauge to the factory location on the S4, which is where the pressure sensor is...(on the UIM pointing towards passenger side.) And the Microtech feed is also on the UIM but on the bottom nipple pointing foward towards the rad (i believe there are 3 nipples intotal there). Now my Microtech reads more vaccum than my acutal boost gauge. I havent driven it yet to see any difference in boost readings, but i figure that it should be the same issue.

While Microtech reads lets say -20hg the gauge will read around 15-17 etc...
Any ideas?

I just remebered, i have my BOV on the same line as my gauge...Could it be that the bov is leaking at idle, so then the gauge is reading less, or would that affect everything?

I would definately hook up the BOV to a different source, since it is open at idle.

BOV open at idle????? what???
never ever heard that before.

I have my gauge hooked up to the same line as my BOV (not the best spot I’m sure) and it reads the same as the Microtech. Your gauge might need to be recalibrated or the BOV is leaking like you said.

Eh, I never knew till the other day when I pointed it out to the guy tuning our cars, he said its normal.

I will have to take your word for it because I personally don't know how it should work.......but if I had to guess I would say that it should be closed at idle.

depends on the BOV really, i prefer to have things hooked up to their own ports than a squid of lines.

my microtech, not hooked up to the car reads -02 Hg, it may be your elevation possibly above wherever it was programmed? i was assuming that as i am 2,000 feet up that it could be reading -02 Hg without anything hooked up to it...

- chris

That was the understanding I had too.

I havent personally checked mine, but noticed another guy's fluctuating when they were checking his timing and thats when I asked.

well, I added a washer to the BOV (its a Turbo xs RFL) and its better, so im gunna add another and see what happens!